The title gets the principal objection of any creationist out of the way: yes, this population of Podarcis sicula is still made up of lizards, but they're a different kind of lizard now. Evolution works.
Here's the story: in 1971, scientists started an experiment. They took 5 male lizards and 5 female lizards of the species Podarcis sicula from a tiny Adriatic island called Pod Kopiste, 0.09km2, and they placed them on an even tinier island, Pod Mrcaru, 0.03km2, which was also inhabited by another lizard species, Podarcis melisellensis. Then a war broke out, the Croatian War of Independence, which went on and on and meant the little islands were completely neglected for 36 years, and nature took its course. When scientists finally returned to the island and looked around, they discovered that something very interesting had happened.
The original population of P. sicula was still present on Pod Kopiste, so we have a nice control population. These lizards are small, fast, insect-eaters in which the males defend territories.
Sadly, P. melisellensis on Pod Mrcaru had been extirpated. So we had a few innocent casualties of the experiment.
The transplanted P. sicula thrived and swarmed over the island of Pod Mrcaru, but they were different, and they had evolved in multiple ways.
The original P. sicula were insectivores who occasionally munched on a leaf; approximately 4-7% of their diet was vegetation. The P. sicula of Pod Mrcaru, though, had adopted a more vegetarian diet: examining their gut contents revealed that 34% of their diet was plants in the spring, climbing to 61% in the summer…and much of this diet was hard-to-digest stuff, high in cellulose. This is a fairly radical shift.
There were concomitant changes. The lizards' skulls were wider, deeper, and longer, and they had stronger bites — a necessity for chomping off bits of tough plants, instead of soft mosquitos. Instead of chasing bugs, they're browsing stationary plants, and their legs are shorter and they are slower. Population densities are higher. The Pod Mrcaru lizards no longer seem to defend territories, so there have been behavioral changes.
Still just a lizard, I know.
Now here's something really cool, though: these lizards have evolved cecal valves. What those are are muscular ridges in the gut that allow the animal to close off sections of the tube to slow the progress of food through them, and to act as fermentation chambers where plant material can be broken down by commensal organisms like bacteria and nematodes — and the guts of Pod Mrcaru P. sicula are swarming with nematodes not found in the guts of their Pod Kopiste cousins.
Here's a photo (how could I resist an opportunity to show some lizard guts?). The top ones may be a little difficult to interpret; what they've done is slit open the tube of the gut, and then use some pins to hold the tube open so you can see the little ridge or flap that rings the interior.
Photographs illustrating the cecal valves in a male (A), a female (B),
and a hatchling (C) P. sicula from Pod Mrcaru. Note the thick cecal wall and
pronounced ridges. The arrow in C indicates the position of the cecal valve in
a hatchling as seen from the outside.
The cecal valves are an evolutionary novelty, a brand new feature not present in the ancestral population and newly evolved in these lizards. That's important. This is more than a simple quantitative change, but is actually an observed qualitative change in a population, the appearance of a new morphological structure.
Evolution created something new, and it did it quickly (about 30 generations), and the appearance was documented. It's still just a lizard, but we expected nothing else — and it's now a lizard with novel adaptations for herbivory.
Herrel A, Huyghe K, Vanhooydonck B, Backeljau T, Breugelmans K, Grbac I, Van Damme R, Irschick DJ. (2008) Rapid large-scale evolutionary divergence in morphology and performance associated with exploitation of a different dietary resource. Proc Natl Acad Sci U S A. 105(12):4792-4795.
- Log in to post comments
As Neil Shubin so entertainingly and persuasively points out, we're still "just fish."
fascinating! take that creationists!
{creo}Different [i]kind[/i] of lizard now? But they're still in the lizard kind!{/creo}
Excellent post PZ!
You mean "principal objection", of coarse.
The creationist tendency to acknowledge microevolution but not macroevolution confuses me. Wouldn't microevolution in a population over a long enough time inevitably lead to macroevolution? What mechanism do creationists propose that would keep microevolutionary changes from accumulating into macroevolution?
I predict some Creationist/ID proponent who believes evolution is consistent with Creation/ID will take this as supporting evidence that evolution need not take billions of years.
Kinds are a Platonic illusion anyway...An animal isn't either a lizard or not a lizard, with an exclusive set of traits that are either 100% lizard or 0% lizard, just like a pile of snad isn't either a pile or not a pile, with the addition of one grain of sand (the Sorites problem) ...And kind(s) can be as big or as small as you like, to fit your argument - from kingdoms (e.g. plants) to species (e.g. dogs). 8-)
Obvious question: can the two populations interbreed? Has speciation occurred, or are the "new" lizards a sort of subrace with a weird mutation/adaptation?
Ok, be patient I'm a little slow... How is this different than for example cross breeding a large dog with a small dog and getting a medium size dog? In other words are these emergent properties typical of cross breeding (in this case with other lizards) or are you discussing something that doesn't happen all that often?
Believing in microevolution but not macroevolution is like believing in inches, but not miles...
Just the sort of thing that Behe typically (perhaps not always) denies, new features which are adaptive. He often likes to say that natural selection just changes things in ways that are functionally about the same, like adaptation to antibiotics often happens to be (he likes asexual organisms as examples because they're less likely to evolve).
To say that it's still "a lizard" begs the question anyhow, since Archaeopteryx is arguably still "a dinosaur", like with all birds (or the creos turn it around to say that archaeopteryx is "just a bird"--making no difference to the fact that it is a radically different bird). Cladistics tends to lump descendents anyway, and the fact that we're all sort of still fishes is demonstrably true.
I'd always like these dolts to explain why organisms have evolved to be even more evolvable, as with sexual reproduction. There is essentially no point to sexual reproduction if some Designer is hanging around causing all of the important changes, but for lizards whose environments have changed (or they moved), it is crucial to shuffling adaptive genes together. Unless Zeus is just very keen on having sex (as the Greeks claimed), ID has no explanation for it, while eukaryote evolution would be impossible without it.
Glen D
http://tinyurl.com/2kxyc7
Prof MTH, I don't quite understand. Is there a school of non Creation/ID thought that maintains that evolution needs to take billions of years?
I heard it said on TO that this might be a case of phenotypic plasticity rather than Evolution. I'm not even clear on what phenotypic plasticity* is, so I was wondering what you guys thought about it.
* I'm Wikipedia-educated
It would be interesting to see if the lizards can still interbreed with their cousins from the original island. The rapidity of evolutionary change isn't all that surprising, given that the original population was only ten individuals.
Another good question is why the lizards went vegetarian. Perhaps the insect population on Mrcaru wasn't large enough?
That is, the evolution observed to have happened in eukaryotes (like malaria) would have been impossible.
Glen D
http://tinyurl.com/2kxyc7
Good article, but one nitpick:
"Then a war broke out, the Croatian War of Independence, which went on and on and meant the little islands were completely neglected for 36 years, and nature took its course."
This is slightly misleading, or am I wrong? The Croatian War of Independence lasted from 1991-1995, and can hardly be the reason why the island was neglected for 36 years.
This is what confuses me about the creationist rejection of naturalism. They claim to stand in such awe and wonder at God and his creation, but then when presented with observable evidence of something amazing happening, they either refuse that it is occurring or chalk it up to God and file it away.
When I walk outside at night, I often catch myself in a prolonged stare up at the night sky. I find myself pondering the sheer, stupefying size and scope of what I'm looking at, and it truly leaves me speechless on occasion. I was talking to a man once who was trying to get me to "get saved" and become born again, and in the conversation I asked him a hypothetical question concerning the personal recognition of God. I asked him how I would "know" when I saw God, and he told me that when I finally was able to see, I would be dumbfounded in utter wonder and amazement.
I don't completely disagree with him (meaning that there is something out there that causes that reaction within me), because I fancy myself a slightly spiritual person, in the sense that I don't think we understand every aspect of the human mental experience, and some of the things we come to know in the future will almost certainly shake our current base of knowledge when we do come across those sorts of things. I took his explanation of recognition to heart, because that is precisely the kind of wonder I feel when I stand at the feet of the immense workings of nature. The difference being, however, that nature has no single face, name, or singular will that can be translated down into a human book like the concept of God. And the only thing we can "do" in service to nature is try to explain what we see in the natural world as we come across it - maybe someday it will all come together and the light switch will come on in our understanding of it all. But then again it might not - all we can do is what we're doing now, exploring the depth and breadth of the universe we live in, and trying to explain it in its own, natural language.
I mentioned I had a spiritual side, but it has already been enumerated far better by a far more intelligent and enlightened mind than mine:
"If something is in me which can be called religious then it is the unbounded admiration for the structure of the world so far as our science can reveal it."
-Albert Einstein
It's still just a eukaryote.
Are there no related organisms that have such cecal valves, i mean, did researchers have to go and analyze this new structure before they figured out what it's use was or did they recognize it?
#5 asks: "The creationist tendency to acknowledge microevolution but not macroevolution confuses me. Wouldn't microevolution in a population over a long enough time inevitably lead to macroevolution? What mechanism do creationists propose that would keep microevolutionary changes from accumulating into macroevolution?"
What mechanism ...? Do you really need to ask? (Hint: He allegedly died on a cross as well)
Correct me if I'm wrong, but I don't think there was any interbreeding going on here. It wasn't like two different dog breeds; there were two different species on the smaller island. They shouldn't have been able to interbreed. The transplanted species just outcompeted the native species.
noncarborundum:
I did not say that it NEED to take billions of years. Rather, the overlap group who maintains that evolution and Creation/ID are consistent maintains that it is possible for evolution to yield homo sapien sapiens in roughly 6,000. I predict that they will use this new evidence to support their proposed time-scale.
Re: #10 by PeteK: "Believing in microevolution but not macroevolution is like believing in inches, but not miles..."
Well said. My own version is that the "micro-evolution yes, but macro-evolution no" mindset is like believing in 1+1=2, and maybe you can continue that kind of thing as far as 3, but there has never been a proven example of going all the way to 10.
Intelligent design does, because it has to predict everything that non-teleological evolution does a posteriori, so that it can claim that the evidence supports both equally (except that ID is actually superior, don't you know).
The design and manufacture process of humanity (certainly the telos for most of these doofuses) over 4 billion years, a bizarre design process by any reasonable analogy, makes perfect sense when the Designer cannot be pinned down to any expectations, and when the crucial predictions of evolution are considered to be merely the happy-go-lucky whim of a designer who isn't close to our standards in many ways (though in evolutionary matters, he's a whiz).
It's all chance with ID, from evolutionary patterns, to the time taken--with nothing expected from a design process (yet not from evolution) ever being visible. It is the ultimate belief that chance can produce everything, which is why they ascribe everything to a God having no attributes, predictability, or explanation. The relative lack of chance in evolution (which is hardly free of it, to be sure) is what they really dislike, for they wish to worship an unpredictable God, not understand life via science.
Glen D
http://tinyurl.com/2kxyc7
I have two questions here, if anyone can answer them:
1. Does P. melisellensis still exist on other islands, or is it now completely extinct?
2. In the article I read, it stated that less than one percent of "scaled reptiles" have such cecal valves. Are there relatives of the original P. sicula that have such valves? Could this be a case of dormant genes becoming activated again, instead of a whole new structure phylogenetically?
I'm curious about this - it seems really interesting, but I'll repeat questions from above that occurred to me as well:
Can the new... species? kind of lizard? interbreed with the old ones, or have they developed a reproduction barrier?
Could (and did) P. sicula breed with P. melisellensis before P. melisellensis was extirpated?
Was P. melisellensis extirpated simply because of the competition from P. sicula?
There are other herbivorous lizards with cecal valves, but no Italian wall lizards with cecal valves--at least until now!
Steve @18,
it's still just the phenotypic expression of a bunch of stupid base pairs.
And anyway, cool as this development is, the lizards are still not as awesome as their cousins P. pityusensis formenterae.
Can you address the genotype vs phenotype question? I'm assuming this is a predominance of one possible phenotype, not a change in the genetic structure of the lizards, and that the genes for this phenotype were already present in these lizards. Is the reason for the shift in predominance of this type of lizard merely a change in environmental conditions? I understand how the predominance of a different phenotype could in time bring about speciation, but changes in genotype take much longer, right?
Only 36 years to evolve from vicious, territorial, insectivores to kind, compassionate mostly vegetarians? Wow, that seems fast.
Let me know when they start driving hybrid vehicles and signing up for PETA memberships.
@ #5
I've never heard any creo explain the mechanism that stops micro-evolution before it becomes macro-evolution. I don't think it's on the AIG site. I make it a point to always ask them for this mechanism, never gets answered.
When pressed they will fall back on their BS about evolution not being able to create new information/structures. So, this is an interesting article to show when someone claims no new information/structure can result from evolution.
Bunny @ #9: I believe you misunderstood the original article. These lizards did not interbreed. The original population of P. melinsellensis became extinct. The changes in P. sicula are due to adaptation (evolution) to new environmental circumstances...not to interbreeding.
BUT WHAT ABOUT PYGMIES + DWARFS??
I share Prof MTH's concern. This could be twisted by creationists to argue that:
1. The few thousand years since their mythical Ark provided enough time to get a host of different species; Noah didn't need to take some honking great number of animals with him.
2. If these lizards could change their diet significantly in 37 years, T. Rex could have given up its coconut diet for meat after the fall.
You're kidding, right? I've heard this theory about geology, but evolution? What they actually need, for THEIR best account, is evolution yeilding homo sapien sapiens in roughly 4000 years--unless they want Christ to be some other species. RECORDED history is damn near 6000 years long! Humans have been WRITING THINGS DOWN for that long! Who are we going to allow? The Hebrews? If only the Hebrews are reliable, recorded history goes back at least 1300 years before Christ (to Ramesses II). In fact the 6000 year figure is calculated on the basis of (biblical) generations of men, so there need to be humans at the beginning of that time!
Is this something new I haven't heard about? Or are these the people who say that "Sure, everything was created, then it evolved--how else do you explain all this diversity now, when Noah clearly couldn't get that many animals onto the ark?"
FPS:
Phenotypic plasticity is just the ability of one genotype to express multiple phenotypes depending on the environment it experiences. While it does not have to involve evolution, plasticity can evolve and can be adaptive. Try this paper for a summary of adaptive phenotypic plasticity S. Via et al., Adaptive phenotypic plasticity: consensus and controversy. Trends Ecol. Evol. 10 (1995),
I think prof MTH is saying that some creationist would use such rapid evolution as an argument for why the the fossil record is the way it is AND the earth is only 6000 years old. I can hear your brain exploding with quick replies to this idiocy, but we're not talking about rational people here now are we?
"just like a pile of snad isn't either a pile or not a pile" - PeteK
Look, it's either a lizard or a pile of snad. God doesn't like fence sitters.
Was there evidence of possible hybridisation between the two lizard species? If there wasn't... Very cool.
Thanks nimravid!
Do we need to wait for DNA analysis to make sure this feature wasn't present in any ancestors and is actually new, not a reactivated expression of already present genes? I mean, if other lizards can do it as well, we'd want to take a good look how the other lizards got their cecal valves.
In response to some of the questions here about interbreeding between P. sicula and P. melisellensis, it should be pointed out that the authors of the study performed a genetic analysis of a few key nuclear and mitochondrial genes. From this analysis alone it was not possible to distinguish the evolved lizards of Mrcaru from the originating population on Kopiste. This suggests that no interbreeding with the existing population took place, and also that it should be possible to back-cross the Mrcaru lizards with the Kopiste population, although no experimental data to this effect is presented.
The authors state that cecal valves are a rarity in scleroglossid reptiles. A morphological comparison between these valves and those of other lizards that possess them may indicate whether this is a truly novel feature or a reactivation of a dormant or pseudo-gene. The question will be difficult to resolve because of the possibility of convergent evolution.
#19: Not quite. for a mammalian equivalents, Island 1 has Wolves, Island 2 has Coyotes. After putting some wolves on island two 36 years, you come back to find the coyotes on island 2 gone, and but the wolves there have shifted their diet and suddenly have floppy ears while the wolves on island 1 haven't noticeably changed.
Argument for Punctuated Equilibrium?
(.)(.)
Does anybody have any before and after pictures? I know the differences are probably subtle, but it would be neat.
Myantek: Even if there was evidence of hybridization it is still amazing. The original species on the island did not have cecal valves either, so they could not have come about due to hybridization.
Here's my guess, as a non-biologist, and without having read the actual paper (so take it for whatever it's worth). I could see the changes to the jaw becoming stronger not involving any actual mutations. If they're eating tougher material, excercising their jaw muscles more and putting more stress on the jaw bones, that in itself could make the muscles bigger and the bone more robust (http://en.wikipedia.org/wiki/Bone#Remodeling). However, I find it much harder to see how the cecal valves could have come about except from a mutation. Any actual biologists want to weigh in on this?
@ Myantek:
According to the NatGeo article
so not hybrids.
None of this comes even close to explaining why the human hand is so perfectly designed for holding a banana. Keep trying.
FPS@#13
The cecal valves don't sound like the kind of thing that could be due to phenotypic plasticity. Phenotypic plasticity refers to where the growth of morphological features is under environmental control. An example is the barnacle penis: barnacles in higher turbulent flow regimes have shorter and thicker penises than those in more sheltered conditions - these differences are not under genetic control and are determined by the environment in which the individual develops. This is phenotypic plasticity (I wrote a blog post on barnacle penises a while back, hence my use of this example).
I suppose it's possible that some of the skull morphology changes might be due to phenotypic plasticity... but it seems doubtful. It would be easy to check - if the changes present in this lizard are heritable, then it's not phenotypic plasticity.
Anyway, this example is great. We're meeting John Lennox on Monday, from what I gather he's rather fond of the old macroevolution vs microevolution/evolution can't produce novelty nonsense. I'm going to print off a copy of this paper, roll it up and hit him in the face with it (OK, perhaps not literally).
There are herbivorous lacertid, agamid, and iguanid lizards that have cecal valves.
The question of whether this is a consequence of a new genetic change or developmental plasticity is a good one, and the authors ask it, too. The plasticity argument would be that if you take any of the original lizards and force them to subsist on a diet heavy in plant material, their guts would respond by developing more muscular ridges. More experiments! It's always more experiments!
Check out the ludicrous attempt to explain this away over at Uncommon Descent:
A kind of form of Larmarckism!
Correct--you're assuming. If your assumption is correct, then this study could be ascribed to phenotypic plasiticity.
There is no evidence, however, that your assumption is correct. No cecal valves have ever been observed before in this species or genus, and are in fact very rare in the entire family Lacertidae (only known in the specialized herbivore Galliota*).
Otherr issues raised above (some, I now see, addressed by others while I tediously typed):
1. This is not a case of hybridization or interbreeding. Genetic analyses show that the introduced population is indistinguishable from the source popoulation (for the markers observed, which would have revealed melisellensis genes if present).
2. Podarcis melisellensis is insectivorous, not omnivorous, anyway.
3. Podarcis melisellensis was locally extirpated on this tiny island, but the species is alive and well elsewhere in the Adriatic area. Their local extinction seems a clear case of competitive exclusion (the subject of the original experimental introduction).
4. No indication of reproductive barriers or speciation, though I doubt the breeding experiments have been done. This is a very short time period.
An interesting comparison: this lizard species, Podarcis sicula, was introduced to Long Island, NY about 1967 and is thriving in many local areas. They still look and act just like the source population (known from genetic studies to be Rome). No herbivory to speak of.**
*Herrel A, Vanhooydonck B, VanDammeR (2004) Omnivory in lacertid lizards: Adaptive evolution or constraint? J Evol Biol 17:974-984.
**Burke, R.L. and Mercurio, R. 2002. Food habits of a New York population of Italian wall lizards, Podarcis sicula (Reptilia, Lacertidae). American Midland Naturalist 147:368-375.
Well I for one welcome our vegetarian mutant wall lizard overlords.
This is a perfect example of where human metaphors for life get put in their place. The ID flaps about 'kinds' are idiotic to begin with. Now when given a contemporary example of evolution in action 'it's still just a lizard' is the best argument?
It's too bad there aren't complete genomes of the original lizards to see if founder effect played a big role or whether this is just a typical evolutionary situation.
Also I'd like to point out that this changed occurred in 30 years!?!?! That's amazing and its no wonder if novel traits can appear in under one hundred generations why there will be gaps in the fossil record. We should take one of the extant lizards and fossilize it just to be sure, heh.
Wow, you mean even the creos are lizards too? Even that slimy lizard, Korn Pone?
Cecal valves wouldn't actually require that much of a mutation; the gut already contracts to move food, and cecal valves are just places where the contractions are strong enough to temporarily close it off. So it could be done by a change in gene expression rather than a change in gene.
OK, it's nearly 4am and I'm afraid of being incoherent (I got lost in rationalwiki and couldn't find my way out)
but basically, most of these changes aren't that radical. What is important, though, is that these animals are changing, and with a different lifestyle, different selection pressures come into play. They can still interbreed now, if they're brought into contact, but in another few thousand years of diversion in the direction of vegetarianism as opposed to the ancestral carnivorism, enough genetic changes could accumulate to make viable offspring impossible. This isn't a speciation event, but it's the start of what might eventually lead to one, and can probably be called one if you ignore the problem of becoming.
Good night, all.
@#25
I was thinking of that question, glad I wasn;t the only one. I guess that might explain why the adaptation appeared so fast
Michael Clarkson @#41
True, so identifying the genes behind the feature might be more informative. I suppose you could then also try to 'switch on' the genes in other related species that don't normally express the 'valve' phenotype.
Larmarckism (social evolution?)
http://www.tufts.edu/as/wright_center/cosmic_evolution/docs/text/text_c…
Epigenetics
http://en.wikipedia.org/wiki/Epigenetics
Fatboy:
While mutations may be the raw source for evolution there is no shortage of genetic variation in most populations for selection to work on, as well as plastic responses that can respond to selection as well. So, these changes do not have to be the result of novel mutations
Holbach @55,
even the creos are lizards too?
If I correctly understand the current systematic consensus, then the lizards are off the hook: creos aren't reptiles (errm, sorry, I mean non-mammalian amniotes).
We're still stuck with them, though.
I doubt this example of evolution will give creationists much pause for thought. After all, (they will say) it's "obvious" that if other lizard species have cecal valves then all lizards must have the inherent ability to have them. i.e. cecal valve are encoded in all lizard DNA but have been suppressed by environmental or other developmental processes.
As PZ says, it's still a lizard, and I can even hear Ken Ham saying just that over and over and over and over and over...
In any case, if it truly is a novel feature, who's to say wasn't God--er, sorry, the Designer--doing a little tweaking while nobody was looking? You can't win with these people.
Artificialhabitat: Phenotypic plasticity does not mean that something isn't under genetic control. Individuals can differ in their sensitivity to the environment and THAT can evolve. For instance, eating tough plant matter might make the tissues in the gut react in some way and individuals with more extreme responses could be favored
Isn't bringing the IDiots, creationists and other like-minded cretins into this charming little tale about like discussing a beautiful sunset with someone who is blind and deaf?
tacitus @ #61
I share your sentiment. And PZ is right. That's what they'll say.
I wonder if we could even get a response from them defining when a lizard is not a lizard. That would be interesting.
Sure.... but that's not quite what I said/meant. I was talking about a specific case: in the example I referred to, the barnacle penises, the differences in penis morphology between individuals in sites with different flow regimes were not genetically determined.
Of course, the capacity for phenotypic plasticity itself can evolve - it can certainly be adaptive.
Thanks for the great article. It's always amazing to see real evidence of evolution in action, no matter the kinds of brain-knot-tying contortions the creationists will use to wish it away.
I must also give kudos to the general commenting population here - lots of smart questions here.
#17 Broken soldier says
"- maybe someday it will all come together and the light switch will come on in our understanding of it all."
Please no. What would we talk about?
Beautiful.
Ha! Can you prove the changes in these lizards are due to evolution and not due to miraculous intervention?
Perhaps my initial comment wasn't clear. I didn't mean to suggest that phenotypic plasticity meant that morphology was entirely under environmental control, with no genetic influence.
Italian Wall Lizards - my new band name.
@artificialhabitat #57: Obviously genetics will be important in resolving what's going on, but I don't think it will be any easier to pin down through genetics whether this is a newly-evolved feature or not. The most definitive result (pseudogene present in originating population is activated in Mrcaru lizards) is the one we are least likely to observe. More likely are subtle changes in promoters that alter the concentration or developmental expression profile of growth factors (or their receptors), in which case we are left with much the same question as with morphological studies.
Posted by: Kitty | April 23, 2008 12:13 PM
Indeed, Kitty, I see your point - that would be a bit of an intellectual and scientific bore. But I do wonder, if that ever happens (which I seriously doubt, by the way), what will the zealots will choose to rant and proselytize about then?
But if these are a new kind of lizard, they why are there still the old kind on the original island? Huh? HUH?
Obviously this is all a trick by satanic lizards to confuse the faithful.
The enzymes from a plant have interacted with the genome? Like, they're primers or homing ribozymes or somesuch? I've never heard of the enzymes from a plant interacting with a genome before, unless of course we're talking about some polymerase... and that wouldn't change the genome.
Still, you have to give the Neo-Creos some credit here. They've actually advanced a testable hypothesis. Now all they have to do is test it, based on some reference to other instances in which a plant enzyme exists that can pass through a vertebrate digestive system, enter the nuclei of germ line cells and cause heritable genetic changes. They've tossed off this explanation so casually that the literature must be teeming with examples of this phenomenon.
Dembski? Luskin? Behe? Anybody? Anybody?
When do rational secularists get to evolve an intellectual cecal valve so we can leave the digesting of religious nonsense to a bacterium infested region thus finally giving creationist/ID claims their due attention and worth?
"Obviously this is all a trick by satanic lizards to confuse the faithful."
I bet those bastard turtles are in on it too!
Not sure it matters. AIUI, we're increasingly coming to the conclusion that most morphological evolution is the result of that sort of "evo-devo" process.
Of course, the creationists will find some reason to dismiss it regardless of the mechanism.
PeteK @7, seems like you're talking fuzzy logic here, but I'm afraid to no end: the average creationist barely understands classical predicate logic.
Maybe god just thought they needed a cecal valve because of their new habitat. Just like he thought we needed to have shellfish fossils on mountain tops to confuse us, so he put them there. It's not that difficult people.
Great science posts lately.
I confess that in the mental turmoil of end of semester, I am more than reasonably amused by the "pile of snad" typo. Forgive me.
So, wouldn't sequencing these two lizard species be rather illuminating?
Regarding "micro" vs "macro", this has always baffled me as well; if creationists are willing to squish a whole genus or more together as a "kind" in which microevolution is allowed, how can they be sure humans and other apes aren't all one kind as well? And that's the line the creationist isn't willing to cross.
No, it's like discussing a sunset with someone who closes their eyes and stuffs their fingers in their ears.
I have a question (sorry for the amateurish way of phrasing it) :
is the appearance of this new morphological structure the consequence of a single beneficial genetic mutation in one individual (a developmental gene ?), like a switch which turned on this new feature, or is it the result of a gradual change (like several successive beneficial mutations within the 30 generations) ?
Since I'm not a biologist or an anthropologist, I don't really have the time to research a lot of the literature or keep up with the developments. That's why this article is so fascinating. It makes me wonder, as a historian, to what extent our genetic makeup differs from those of Romans, or the ancient Steppe riders that many Europeans descend from. There doesn't seem to be much difference.
The Romans were remarkably short; 5'9" was a tall man. Yet among the Germans and Gauls it wasn't rare to see men 6' or taller. Besides, the majority of the height disparity can be blamed on the nutritional deficiencies during childhood most pre-modern people experienced.
I guess my question is, if we haven't seen any major changes in the human genome over the past thousands of years and these lizards practically speciated in decades, why? Is it gene flow? Certainly there are cases of isolated populations of Humans who were cut off from outside populations for significant amounts of time? Does anyone know where i could get information on this?
Mike O'Risal @ 76
Thanks for addressing that question. It does seem that they have advanced something testable - but I am not a biologist by any stretch. Of course, when their tests flop they'll just move the goal posts. That's why I would like to hear from them precisely when a lizard is no longer a lizard (or a dog no longer a dog, etc., etc.). Make them paint themselves into a corner with their illogical assertions.
I can only assume the ID "researchers" will be all over this little island now.
What a chance to explore the island where the intelligent designer did his thing within the last 30 years, you can practically still smell him (or her!).
It's a pile of lizard snad!
AgnosticTheocrat:
Have I got a paper for you!
Hawks J, Wang E, Cochran G, Harpending H, Moyzis R (2007) Recent acceleration of human adaptive evolution. PNAS 104(52): 20753-20758.
It's open access, so enjoy.
Well, of course he meant that.
Sorry. Couldn't resist.
Uh, am I the only one here smart enough to notice that you can {creo caps}CLEARLY SEE JESUS CHRIST'S FACE IN THE LIZARD GUT ON THE RIGHT?!?!? {/creo caps} His beard and everything. His crown, too.
So, obviously, Jesus gave the lizard a new gut. Or Satan did, to fool you. And, that is, Jesus let him, to confound and fool you foolish fools. They probably had a bet on it, too, and ate pretzels, just like in Job.
But we have seen major changes in the human genome in the past thousands of years. But there are differences, obviously humans have longer generation times than lizards, and can also develop cultural solutions to hard-to-digest food etc.
PZ, quick question. Has it been shown how much of the morphological, behavioral, and other changes are due to changes in the genome, verses a phenotypic reaction to the new environemnt? Not that it couln't be all be natural selection on the genome, but I recently saw a documentary on pigs, where it was shown how even adult pigs change the color of their fur and the *shape* of their snouts (they become more shovel shaped), if allowed to go feral. As an additional "control" it would be interesting to see what, if any, phenotypic changes occured to the adult lizards and/or to the very first generation of offspring in the new environment (perhaps by introducing adults again from the founding population, and watching them all closely).
Please note: I'm not a creationist wacko trying to weazel out the evidence... I'm just curious about whether what we are seeing is the result of 30 some generations of natural selection, or a sort of "built in" and perhaps somewhat vestigial adaptability that has already evolved over the passed thousands or millions of generations, or more likely some combination (and to what degree) of both.
OK, that was not-so-quick-a-question. Hope you have time for a thoughtful answer.
Waitaminnit! I can see information causing an ID proponent to revise their understanding of ID--microphilosophy, if you will. But to go from ID to Lamarkism? Macrophilosophy--going from one kind of understanding to a totally different kind has never actually been observed.
This Lamarckism stuff is weird indeed, since when do creationists refer to commie atheists and their explanations?
Ryan wrote:
It seems to me that in this case, there is a shortage of genetic varation, since the founding population was only 10 individuals. If the variation was already present in those individuals, shouldn't it have been present in the original population from Pod Kopiste? Wouldn't you expect to find at least some individuals on that island with cecal valves if that were the case? Maybe not. As others have commented, maybe just switching to that much vegetation in the diet could make the intestines more muscular. I'm really looking forward to seeing the follow ups to this.
This is a beautiful example. Maybe I'll stop skimming over the Ecology & Evolution sections in PNAS now.
Cecal valves wouldn't actually require that much of a mutation; the gut already contracts to move food, and cecal valves are just places where the contractions are strong enough to temporarily close it off.
Not necessarily. Very often valves are not muscular in their makeup but rather they are mesenchymal cells that are secreting lots of extracellular matrix proteins to make the valves more resistant to stress/strain/force so that muscular contraction- an energy dependent event- isn't required for dividing the regions separated by the valves. If this were the case it would take a tremendous amount of changes in gene expression within the muscle but a more simple event to make more mesenchymal cells and valves.
So many great questions. I love the reader ship here.
So the secquence of events is something like this? - the imported lizards were better at catching insects the locals and as a result they outcompeted them for the ressources to the point where the insect population became too low to sustain them.
The imported lizards were partial herbivores before the moves, so they had an edge in switching their diets after the loss of insect life. Does that mean that the indigenous lizards were obligate insectivores with no backup foodstock?
I read that as "pile of snot" at first - how very bizarre.
IDiots avoiding a straight answer!
That is SLANDER, sir! Surely such a thing has never happened.
But why didn't some of the lizards turn into PYGMIES + DWARFS????
"This is slightly misleading, or am I wrong? The Croatian War of Independence lasted from 1991-1995, and can hardly be the reason why the island was neglected for 36 years."
Exactly. The intelligent design changed these lizards biology and the scientists just "happen" to not be around to witness it.
These scientists need to just admit what happen and stop trying to cover-up the Truth!
Well, it isn't an elephant from a bacterium, so it doesn't count.
Plus, where are the intermediates? Maybe the Biologic Institute (you know, they have a website now--can you imagine how much great work they must be doing?) should look into this, because they might be able to observe the Designer in action if they were to replicate this. No intermediates means that cecal valves might damn well have been poofed into existence by the Designer--or aliens mighta dunnit.
Glen D
http://tinyurl.com/2kxyc7
Brilliant. Of course there will be several "but the lizard is STILL a lizard, not a dog." type of accusations. When will the IDers learn that lizard to dog equals magic, NOT science? Evolution is NOT alchemy.
If you want magic then stay in church... science is all around you.
But what good is HALF a cecal valve? Obviously, the lizard has been touched by a noodly appendage somewhere along the way, as cecal valves are often served with rigatoni.
OT, yet not so much:
Better than the House bill, but still pretty clearly targeted at one scientific theory for one reason alone--religious tampering with education.
Glen Davidson
http://tinyurl.com/2kxyc7
Brandon P. at #5 asks:
"The creationist tendency to acknowledge microevolution but not macroevolution confuses me."
I think this gets at the heart of the debate.
"Wouldn't microevolution in a population over a long enough time inevitably lead to macroevolution?"
Well, what makes this transition to macroevolution inevitable or even realistically plausible? If I am blindfolded and drunk, I can realistically see myself getting across the room without any help. It is also conceivable that, without any help, I will make it across New York City by foot: doing so just requires that I take one step in front of the other in the right places and moving in the right directions. But does this mean that it is realistically plausible that, without any help, I will make it across New York City by foot while blindfolded and drunk? Surely not. Similarly, we should not just assume that random mutation + natural selection realistically has the power to transform simple cells into the staggering diversity of living forms we see today, merely because of some examples of microevolution.
"What mechanism do creationists propose that would keep microevolutionary changes from accumulating into macroevolution?"
They do not propose a mechanism. They are just skeptical that undirected processes like RM+NS realistically have the power to produce macroevolutionary change. It may have such a power, but it is evolutionists who have the burden of proving that undirected processes ARE realistically capable of such radical change. It is not enough to just point to examples of microevolution and say "See, macroevolution is just more of the same." That would be like pointing to a drunk blindfolded man stumbling across the room and saying "See, going across New York city on foot while drunk and blindfolded is just more of the same."
More argument here is needed from the Darwinist side before undirected macroevolution becomes a realistic possibility.
Damn right! I want to know, if you threw this lizard into a junkyard, would it build a 747???
Hugh at #107
If the travel was truly random, with enough time you would get to New York. And Moscow. And Yemen, etc..
But Natural selection provides a directed force such that if it generally pointed you toward New York, even in your drunken staggering state, there is a strong probability you would get there in time. But NS doesn't necessarily work in such a simplistic way. Your analogy is way over-simplified to be meaningful or accurate.
And there are explanations that support the selective mechanisms. Where is it said that NS does not apply to macroevolution (a mis-informed term)? The reason ID needs to provide its explanations is so they can be tested. Evolutionary biologists have been doing that for many years now.
Just the sort of thing that Behe typically (perhaps not always) denies, new features which are adaptive.
Does Behe even think that microevolutionary changes occur? I have to wonder based on the arguments in his recent book.
As an aside, there is an interesting article in PLOS Biology by the Joyce group, "Darwinian Evolution on a Chip." Brief quote from the discussion section: "The constellation of mutations that arose over the course of evolution could not have been anticipated, especially the triple mutations within the M3 region that had the most dramatic effect on Km and the paired M4 mutations that only had benefit when combined with the other mutations. It is not surprising that these more complex traits arose later in the evolution process."
The Croatian Spring was in 1971.
"But does this mean that it is realistically plausible that, without any help, I will make it across New York City by foot while blindfolded and drunk? Surely not."
But surely if everybody in New York City started on one side and tried to walk to the other while drunk, many would make it to the other side. Even if some of the blindfolded drunk people started trying to kill off other drunk blindfolded people in order to prevent them getting to the other side, they would not be able to get them all, and their behavior would be counteracted by other drunk people leaning on each other for support, and thus increasing their chances.
What if you have a million people drunk and blindfolded, trying to get across New York City on foot? What's the chance that several of them will make it, especially if everyone else is drunk and blindfolded?
That's a, what do you call it?, relevant metaphor.
@90
That was a fascinating article! It oddly seems to contradict this current story though, which I find interesting. The article attributes the accelerated rate at which alleles diffused through the human population throughout the past 50,000 years to the dramatic increase in population. As the population increased the number of mutations increased at the same rate, allowing a higher probability that a beneficial mutation would arise and proliferate. Gene flow has allowed an effective means for mutations instead to spread quickly throughout large parts of the species. Humans are evolving quickly because there are so many of us, at least a few of the hundreds of millions of offspring a year are bound to have a positive mutation.
This is counter to my understanding of population genetics as I was taught in Anthropology (of course, to be honest, it was an entry level college course). From what I was told, Gene Flow tends to restrict evolution since it eliminates diversity and stalls Genetic Drift. Obviously this is the complete opposite of what the article finds.
What's odd though is that the lizards are the complete opposite of our species' situation. Rather than billions of members there were only 10, and such a low number would limit the chances for a beneficial mutation. Obviously, after several generations this number would be far higher, but the concept is the same. This is a polar opposite context than the one our accelerated evolution takes place in.
I'm not arguing against evolution, ha, FSM knows I'm no fundie. I'm just constantly amazed at the complexity of the natural world, and find it fascinating to learn more about the mechanisms which make it tick. I just don't have the time to study these things enough to call myself well informed. College Undergrad takes it's toll unfortunately. "Scientifically Literate" is about the best I can manage.
Are the lizards just a function of the founder's effect? A fluke situation where the highly unlikely chance of a beneficial mutation happened in an easily observable time frame? Or am I missing a key mechanism in genetics that would lead to the contradiction?
Damned if you do, damned if you don't, really, because all evidence for evolution is evidence for creationism. Major evolutionary changes can't happen, but if they do, it's because the creature or the creator willed it so.
That's not just moving the goalposts, that's removing them and the touchdown line.
It's depressing reading Science & Creationism from two decades ago and seeing that nothing has changed.
We have ceca. Who can we put on small islands to see whether the ceca enlarge as they become obligate herbivores like howler monkeys? I have a short list in mind :)
Hey, a peer-reviewed science post with over 100 comments! This is great!
Speaking of lizards and possibly exaption.
Could be genetic assimilation, and the population's reaction norm of gut morphology has shifted.
In any case, this is a very impressive example of adaptive evolutionary change in metazoans.
But not impressive enough for the creationists. Nothing is. Creationists can simply move the goalposts and say that both the original population and the isolated one with the new gut morphology belong to the same "created kind." Some creationists think that only representatives of genus level or even higher were initially created and so the species diversity we see today is the result of "microevolution." (Even though microevolution would be a grossly inaccurate term.) There are creationist websites that discuss inter-species, even inter-genus, hybrids as examples of mating within "created kinds."
So Sili @ 117, would that be a glotopod or a linguipod?
From my viewpoint as an observer of these phenomenon, clearly limited by my inability to understand all the vagaries of the jargon and delicacies of these specialized sciences, I offer the following:
Thought the comment about jaw size increase being related to exercise-stress on jaw from eating tougher herbs might be relevant.
The poster who pointed out that these gut muscles are already present and modifying them may be a smaller genetic task than one might suppose has a ring of truth. Reminds me of a show I saw on Nova/PBS/Nature recently that showed how environmental circumstances from several generations deep could have serious consequences many generations later with some predictability. It was premised on genetics and the nature of our DNA/RNA and seemed to stress a new micro dimension to DNA that was gaining favor.
I too welcome our semi-naturally selected, heavily bowel-muscled reptillian overlords.
Enjoy.
Whoaaah, Wait monkeymen, before you self-proclaimed animals can make an honest claim to have found your first ever evidence for macroevolution consider what you are saying and prove your facts. First, you must show that none of the mate capable lizards on the island did not have latent genes for the valve to have formed by natural selection- yes we creationists embrace natural selection as the Creator's means for habitat adaptation (dark rabbits are easy prey in snow leaving only white rabbit DNA) Step one: Find all lizards that have lived on the island during the 30 odd years in question, even the dead ones (you must include one generation prior to the transferred animals they were their mates); do an analysis of each lizard's gene composition and deternime that not one had the valve related gene composite. If this can be accomplished and only then, can a claim of macroevolution (frog to prince style) be truthfully made; anything less than each step accomplished and you only have an unproven hypothesis. Hey then go ahead and file a lawsuit to claim Dr. Dino's $250,000 dollar prize (see www.Drdino.com type $250,000 in the search field)for finding the first empirical evidence for evolution, you'll have instant national attention and the chance to make yourself some pocket change.
You all do realized that science has just opened a gap between the Podarcis sicula Kopiste and Podarcis sicula Mrcaru since no one observed each and every animal of the species in those thirty six years. How can science prove that God didn't send an angel to modify the lizards while science's unsuspecting back was turned unless it has an every animal of the species that ever existed?
This fits in better with the TRUE Christian™ theory of Punctuated Wrath; God creates a species, God is displeased, God smites species, God then creates a new species that is slightly different from the original species. It's hard to imagine what Podarcis sicula did to incur God's wrath but clearly with their gut valves He stuck it were the sun don't shine. I am sure somewhere on Mrcaru someone will find a bunch of burned Podarcis sicula corpses.
Hugh, undirected is not accurate. NS determines when mutations are useful those mutations will propagate through the population. When people say that evolution is just about random mutation, they are wrong.
Besides, evolution by NS works on populations, not individuals, so building a metaphor with just one person in it will not get you anywhere.
You're not thinking about this correctly -- "getting across New York" is a goal. Your analogy only works if evolution is teleological, which it's not. The correct analogy is to place a bunch of drunk, blindfolded people in Kansas, and let them walk for a long time. Some of them will remain in the vicinity of Kansas. Some of them will end up in New York, California, Alaska, etc. if you wait long enough.
Years later, we'll look at the folks who survived and settled down, and talk about how everyone must have had some help to have all ended up in such hospitable places. But the reality is that we're only seeing the people who happened to drunkenly wandered in good directions -- the ones who ended up freezing to death in the Yukon, or falling into the ocean and drowning, were lost to history.
For the record, the Croatian Spring was not a civil war.
Michael woelfel, i looked it up, frogs do not turn into princes.
god obviously loved Podarcis sicula enough to give it new cecal valves so it could survive on the island. What did Podarcis melisellensis do to piss him off?
Artificialhabitat - You and your barnacle penises... :-)
michael woelfel @ #121
And what creo-bots need to do is explain why there are no rabbit fossils found in proximity with dino fossils.
It's hilarious how good creationists are at demanding more and more from those who would confound their world-view. They however (the creos) can't even explain the simplest of their claims without ultimately referring to their ancient book of shepherd myths.
#114
Not quite correct, it's not that evolution is always faster in small populations, but the kinds of evolution are different in small and large populations. In small populations drift is faster, in large populations selection is faster (other things being equal) However, even small amounts of gene flow can counteract divergence and local specialization. The lack of gene flow between the two islands would have made local adaptation 'easier' in this case.
If the change would be solely due to founder effect (drift), there's no reason to expect it to be beneficial, it could just as easily have been a curly tail or something else that doesn't help them adapt to their environment better. The morphological changes are correlated with the diet, which suggests that selection is involved.
But they have yet to find a crocolizard! Now, consider this banana....
Alex, that's the creobot strategy known as "persistent and unwavering moving of the goalposts". They do it all the time. Any time you substantively answer one of their challenges with the facts, they ask you to provide more facts, and then more, and then more. The point of this is to keep increasing the scope of the evolution question so your answer becomes untenably weighty (no matter how fact-based), and then they jump at the slightest opportunity to tear it all down because they get you into a spot where you're making excuses for why evolution includes so many things. They goad sane thinkers and scientists into turning the evolution argument - a scientific one - into a philospohical discussion that anyone can have any opinion on because philosophy doesn't deal with facts the way science does. Philosophy is far more susceptible to interpretation on the level they like, which means it allows them to see evil where none exists, and to make assumptions that are faulty because facts have so much less direct bearing on decisions.
I strongly approve of this speciation. :-P
(Also, these results are SO. COOL.)
Yep, that nicely addresses one of Hugh's misconceptions: evolution acts on populations, not individuals.
The other reason Hugh's analogy fails is that he is assuming a single, fixed outcome (going from one end of NYC to the other), but evolution has no such predetermined goal, certainly not in the long term.
Basically, every microevolutionary step is to allow immediate survival in current circumstances: in this case, the ability to digest an insect-poor, plant-rich diet. Other, different circumstances may arise in the future to enact further changes so that you eventually end up with a lizard with a cecal valve AND, I dunno, thumbs if they need to strip vegetation like pandas.
Additonally, since mutation is random, there are potentially multiple stategies to enable survival. Perhaps there was another possible change that could have enhanced the lizard's ability to catch insects.
In other words, a better use of the "drunk walk across NYC" analogy is to set modest, microevolutionary goals at each stage: say, "travel two blocks". When some drunks meet that objective, they "survive" and reproduce (adding more drunks), and have to meet the next goal, getting another two blocks.
As a result, the drunks may end up in Brighton Beach, The Bronx, or even Staten Island. They got across NYC, eventually (macro), after achieving the individual micro goals. But it doesn't mean that they were "meant" to get across NYC, and certainly not the specific location they ended up at -- that's just how it panned out.
Deal out a hand of poker. What are the odds that you got that specific hand? Pretty astronomical, yet it doesn't mean you weren't dealt a hand at all. That's the folly of that sort of reasoning.
Woah there idiotman, Dr. Dino is in jail for tax fraud and if he fails to render unto Caesar as the bible says, then what is the likelihood that he'll pay up, almost none, so why don't you check your facts before you spout off, oh wait, you don't have any.
[My apologies to the literate denizens of Pharyngula, but vacuous morons like michael waffle need to be responded to in their own language if there's to be any hope of comprehension. Hmm, on second thought, I needn't have bothered.]
michael woelfel:
That would be ape men, not monkey men. Zheesh, can't you guys even get that right?
By the way, there's plenty of evidence for evolution. You just need to get your fingers out of your ears and to open your eyes. In other words, it wouldn't be an earth shaking discovery. I do find it rather telling that you want to find every animal that lived there during the duration of the study. We both know that that's not going to happen, and even if we did you would just find something else to nit pick about. By the way, where are the remains of Noah, Adam, Eve, Cain, Abel, etc? We want to be able to test all of those, can you do that? Otherwise we can't believe in creationism, sorry.
#29 to answer your question. For a sub population to evolve to be different from the parental population no new mutations need be required (though they can play a role).
1. Assume that the full panoply of genetic variation of the parent population was not present in the 10 colonists. So even without any environmental selection pressures over time they would differ simply by genetic drift uncorrected by interbreeding with the wider parental population. This is called the Founder Effect and is the basis of much specialisation in isolated island species. Remember Dodos were simply big flightless pigeons, their ancestors flew to Mauritius.
2. What happens is that Gene Frequencies change over time. So an allele present in the parental population but present in only one of the founders might disappear, or it might come to predominate. Again this can be just by genetic drift.
3. When you add in selection pressures: a different environment with a competitor population as well perhaps food scarcity. Note that the founder population now lives at higher density than the parental probably enabled by the move to more herbivory, plants being more reliable and easier to catch than insects.
4. Features like jaw size and shape are affectable by multiple genes, all of which may vary meaning there may have been enough variation without new mutation to drive a change. What seems to happen in populations is that being heterozygous at many genes (having 2 different alleles for many genes) stabilises the phenotype. Those variants act a bit like thermostats, so if one allele by itself pushes jaws to be wider another will counter it. So if the founder population, having less variation and under selection pressures become less heterozygous then those alleles that promote jaw growth will predominate.
As others have said you can do this sort of thing simply by changing gene expression. It can be as simple as letting a structure keep proliferating for a bit longer. Or a controlling factor like a local acting hormone can be left on for longer or the cells made more senstitive to it. Or a combination of those to varying degrees. Remember, evolution cares not one jot about mechanisms (unless they be too energetically expensive), only about outcomes, in this case jaws adapted to eating plants. This is just like Darwin's finches.
BlueIndependent @ #131
Thanks for the commentary. Spot on. I am very, very familiar with their methods of debate. They are extraordinarily dishonest. Sometimes unwittingly, other times purposefully. Moving the goal posts is quite common for them. They will do anything, even break every one of their precious commandments, to protect their cherished comfortable beliefs. It must be so irritating to them that a bunch of really smart people have been finding problems with their primitive world-view for hundreds of years now. It used to be that they could just jail them or kill them. In this day and age, the amount of confounding empirical data they have to contend with must be so overwhelming. I can't even begin to imagine the cognitive dissonance. They have deceived themselves to the point that they will blatantly act out in violation of their dogma, in defense of their imagined deity, to make themselves feel relevant.
That is incredible for about 40 years of mutation. Quite an extreme change. Lovely find.
Wowzers! I love stories like this! What journal is this paper in? I must have a copy!
Don't forget about the godless physics.
http://newsbyus.com/index.php/article/300
The mythology of godless physics is probably too broad a subject for even a talent like Ben Stein to embrace in a single film.
There seems to be two ways of looking at this: (1) that NS has brought all of these changes about; or (2) the environment, specifically the proteins/enzymes/chemicals of the plant life on the new Adriatic island has interacted with the genome to quickly bring about these changes.
Maybe I missed something back in university, but isn't (2) still NS? My understanding is that natural selection works on the premise that changes in the environment cause differential rates of reproductive success(fitness)within a population. It seems that having been tossed into a different environment, a slight variation within the starting population has been acted upon causing a change in the physiology of the population of lizards.
Maybe this change hasn't existed long enough to become fixed in the population, and they could revert to the control physiology, maybe they can still interbreed. Given more time if the population becomes unable to interbreed is this not the formation of a new species by natural selection?
Sorry to appear stupid, but calling option (1) NS and saying (2) is not, seems like saying if we can identify the specific selective pressures ( lack of insects, lots of plants with chemicals that impact the genome) then this is not natural selection. And if a change in the environmental pressures acting on a population and causing them to significantly change to the point they are no longer interbreeding with the initial population, is not what is meant by natural selection... what is?
What I find most interesting is that it took all the way to comment 107 for the first cdesign proponentsist to show up... but, as expected, he mentions natural selection twice without evidently having the slightest idea of what it is...
What rubbish. That makes it obvious these cdesign proponentsists don't have the slightest idea about mutations, and probably not even about what an enzyme is. What they propose amounts to a miracle (...how fitting).
I recommend comments 76, 95 and 96.
A slimy lizard would be even more surprising than one with cecal valves! :-)
So... a change in a regulatory gene. :-) Perhaps just one, though.
:-D
Apparently not.
I can think of two cases. One is the population of Easter Island, which was isolated for a few hundred years. The other is Tasmania, which was probably isolated for several thousand years, but it's so large that "isolated" doesn't make much sense, and it isn't so far away from the Australian mainland that occasional contacts could be ruled out.
[voice=Creationist/IDist]
Big F'ing Deal! I don't see any of them giving birth to a cat!
[/voice]
That said, pretty cool stuff. Nice lizard gut-shot.
T
YESSS! I managed to get Comic Sans in! Praise preview.
<p style="font-family:Comic Sans MS">
Oh, but the lizard didn't evolve in something truly exceptional, like a fire-spitting lizard or a dog. Cecal valves, ha. Is that the best evolution can do in 32 generations?
I stand unimpressed. It's pretty obvious that Gowd wanted to trick all those satanic atheist evolutionists and made this thing grow cecal valves. And He also caused the Croatian War of Independence to trick them even more.
You are all missing the point! This was foretold in the Old Testament.
These lizards are clearly frontloaded for cecal valves. The Designer knew they would be kidnapped in 1971 by evil Darwinists and transplanted.
They are also clearly god's the Designer's chosen lizards. They managed to exterminate the resident Canaanite native species in a minor genocidal incident. And they don't eat shellfish or wear clothes made from two different fibers.
Like Ham says, you need to look at the data through the lens of the bible to really understand what is going on.
The article still leaves me with a few questions in mind- how did the control population change on Pod Kopiste (if at all during this period). Also I would want to know just how different the actual islands are, the prey insect population differences then and now, etc, just to get a better understanding how these lizards evolved so quickly. That is the most interesting matter to me- that this change took place so quickly. So many times I read how evolution must take millions of years, and I just think "what a crock" and now we have a good working example of how quickly it evolution can occur.
phenotypic plasticity
THANK YOU for this term (from a non-biologist). I've been trying to find a way to think about how environment affects gene expression but didn't know there was a term for it. This makes a lot of sense.
No, no. Gene flow tends to prevent populations from splitting into one population that has the mutation and one that lacks it. Instead, it helps beneficial mutations to spread through the whole population.
LOL! Obviously exaptation.
What does that mean?
Whoaaah, wait, loamman, that you say "prove your facts" proves that you don't know what "fact" means.
Nope. You only need to screen the parent population where the 10 founders came from for any such genes. This population still exists.
So you don't know what science is either. Science cannot prove, only disprove. Proof is only for math and formal logics.
It's unlikely.
The genetic tracing was done through mitochondrial DNA (it's supplementary figure 5 in the original article) and all mDNA recovered was very similar to existing P. sicula mDNA and quite different from P. melisellensis mDNA. Now, mDNA is inherited solely matrilineally, which suggests that P. sicula were the original mothers of all lizards born on that island, and unless interbreeding were completely sexually deterministic this would not happen if the species interbred.
A lizard will remain a lizard
Even if it grows a gizzard.
Even if it grows some fur,
A lizard's what it always were;
A lizard will be of that ilk
Despite evolving glands for milk;
A lizard with an upright stance--
Could that be different? Not a chance!
A lizard standing on two legs,
Who bears live young instead of eggs,
No matter what, you'll always find
It still belongs to lizardkind.
Hmmm....
At last I think I understand
Some crazy things about this land:
The audience for Bill O'Reilly?
Lizards prob'ly rate him highly.
The changing views of John McCain?
The answer's simple: Lizard Brain.
Paris? Brittney? Cher? Madonna?
Must look hot to some Iguana.
I think I'll stop here, if you wish--
It's time to feed my inner fish.
http://digitalcuttlefish.blogspot.com/2008/04/lizard-is-lizard-is-lizar…
If P. melisellensis was mostly insectivore, I wonder if it could be reintroduced and if it would coexist with the transplanted P. sicula. The insect population must have exploded on that island.
It can never be said too often: Cuttlefish, you are brilliant.
ID-wise, i.e. "information" "theoretically", I think it is genetic change that matters here, not just phenotypic change. What seems to be the most dramtic implication in this post is that the genetic information for cecal valves was supposedly generated by evolution in mere 30 generations, during which time a whole sequence of new alleles gradually became fixed in the population. I have to say that such an idea sounds quite incompatible with the mathematics of population genetics. And one doesn't have to be Walter ReMine-ish to express this scepticism.
It sounds much more feasible to me that in this case the "genetic information" for cecal valves was in fact inherited from the ancestor of the genus or family, and that perhaps even the regulatory mutation turning the valves back on in the phenotype was originally present in one of the ten individuals. The founder effect would then have helped to fix the new phenotype in mere 30 generations. This assumption would mean that there in fact are, or at least were in 1971, occasional rare individuals with cecal valves on Pod Kopiste, too. This phenotype just isn't favored on the original island and remains either harmful or neutral variation.
Feel free to criticize!
Just when Shubin was getting me comfortable with my inner fish, here comes that nasty atheist PZ straight from the Central Committee with orders for me to get comfortable with my inner lizard . . . . . . .
Nimravid at #27, Sven DiMilo at #52 -- thank you for your clarifications. I was concerned about an experiment that involved wiping out a species, but I'm relieved that P. melisellensis is still abundant elsewhere.
Meanwhile, I hope someone can get funding for research into just how much genetic change was involved in what looks like nitro-fueled evolution.
Nah. Lizard densities are now higher, and the P. sicula in question are omnivorous, with insects >40% of the diet.
There seems to be two ways of looking at this: (1) that NS has brought all of these changes about; or (2) the environment, specifically the proteins/enzymes/chemicals of the plant life on the new Adriatic island has interacted with the genome to quickly bring about these changes.
Maybe I missed something back in university, but isn't (2) still NS?
Yes.
I think many of us missed something if we studied evolution 20 years ago or more: the influence of selection on regulatory genes (which, while known, was not thought to be as pervasive as we seem to be finding out now), and the influence of epigenetics on regulatory genes.
This is relatively new information, and, as has been the case for so long now, does not invalidate the role of selection as a mechanism, just refocuses where selection might act.
for those unfamiliar with the study of epigenetics, there was a nice introduction on NOVA a few months back that at least scratched the surface:
http://www.pbs.org/wgbh/nova/sciencenow/3411/02.html
I have always rather thought of it as the continuing "evolution" of our understanding of how units of heritability operate. In Darwin's day, he had no clue what DNA or genes were. 30 years ago we thought the 1 gene -> 1 protein model was sufficient. Now we know that isn't exactly accurate either, and having mapped the human genome, we now are thinking to map the "epigenome" as well.
Selection as a mechanism keeps on truckin' even as we learn more and more about how the genome interacts with the environment.
Did the now extinct species Podarcis melisellensis have cecal valves?
The founder effect would then have helped to fix the new phenotype in mere 30 generations. This assumption would mean that there in fact are, or at least were in 1971, occasional rare individuals with cecal valves on Pod Kopiste, too.
It certainly wouldn't be hard to test that assumption now, would it? Well, except for the "were" part. However, it would seem unreasonable to assume that the parent population would no longer possess the relevant gene(s) for cecal valves. So, yeah, it would seem a reasonable thing to do to look at the genetics of the parent population to see. I haven't read the paper, but perhaps they have already done this?
That's the great thing about studies like this:
They end up creating a ton of new questions, each one of which would be a decent PhD thesis.
Did the now extinct species Podarcis melisellensis have cecal valves?
it's only locally extinct to that tiny island, just to be clear.
If you're thinking interbreeding, that question has already been addressed.
I'm just about to sit down to a nice steaming bowl of snad right now. It reminds me of Gagh, actually.
Its still a lizard who knows god might have decided to change it to fool all you non-believers?
who knows god might have decided to change it to fool all you non-believers?
now all you have to do is figure out how to test your idea.
I hope for your sake, your post was intended as parody.
no, wait, even as parody it sucked.
However, it would seem unreasonable to assume that the parent population would no longer possess the relevant gene(s) for cecal valves.
Certainly. I was merely including the (improbable) possiblity that the phenotype itself might have become even more rare recently than in 1971, due to purifying selection.
So, yeah, it would seem a reasonable thing to do to look at the genetics of the parent population to see. I haven't read the paper, but perhaps they have already done this?
Nothing in the paper suggests to me that the genes for this trait have even been identified so far.
"Does Behe even think that microevolutionary changes occur? I have to wonder based on the arguments in his recent book."
Depends on who is paying him.
@Ichthyic its just a lizard whats so impressive about it has a few adaptations. But you guys are jumping overboard and declaring that a new species will emerge in a couple of thousand years.
Ichthyic already responded to your good question about the genetics of the parent population, and, like him, I haven't yet read the paper, so I can't say whether they have done that yet or not.
I don't have a criticism, just a question about something in your post I don't understand:
I'm not sure why you're saying that ID is some kind of synonym for "information" or "theoretically", since biologists and informaticists use "information" and theory all the time without resorting to ID as an explanation. So I'm not following your equivalence here.
I'm not sure why you're saying that ID is some kind of synonym for "information" or "theoretically", since biologists and informaticists use "information" and theory all the time without resorting to ID as an explanation.
Apologies for my confusing, short-hand language. I was referring to the fact that the ID folks won't be interested in anything else than: did evolution create new information? (And Dembski would additionally ask whether it was more than 500 bits to be "complex" enuff for him.) Well, I just don't think evolution had enough time to produce novelties here -- it just isn't mathematically feasible.
Certainly. I was merely including the (improbable) possiblity that the phenotype itself might have become even more rare recently than in 1971, due to purifying selection.
again, that seems pretty unlikely, yes? More likely if the populations really ARE completely isolated (even a single migrant can prevent fixation), but there are other mechanisms that interfere with fixation as well.
I'm going with the more likely scenario that this might represent changes to a series of regulatory genes, rather than a completely novel gene, or that we see a rapid spread of a specific genotype from the original parent population.
Like I said earlier though, it would not really be that hard to find out.
even if we assume that all the relevant genes and regulatory genes involved in the changes we see in the new population have been suppressed in the parent population, traces would remain; it's extremely unlikely they would have been entirely excised (especially given the time frames involved).
Esko: your scenario is not necessarily opposite to the natural selection hypothesis. For example, imagine that the cecal valves are quantitative traits governed by several genes, like human height. A lizard with only "no ridges" alleles gets a smooth stomach, a lizard with 1-2 alleles gets a small ridge, and so on, until a lizard with the right alleles at all loci gets the full cecal valve. All these alleles may be present in the parent population, but so rare that you practically never get the noticeable "cecal valve" phenotype, before natural selection makes the relevant alleles more common. This is how you can get a new structure out of existing genetic variation.
Of course this is just a hypothetical scenario, and the valves could be due to a single mutation.
your scenario is not necessarily opposite to the natural selection hypothesis.
not to step on his toes, but I don't think that's what he was implying.
He was proposing a mechanism based on founder effect, which the authors COULD have easily controlled for (and very likely did), but it's unclear based on the quick overview of the paper presented in the thread.
Thank you Cuttlefish - I'm going to smile all morning.
I'm going with the more likely scenario that this might represent changes to a series of regulatory genes, rather than a completely novel gene
This was never in doubt here. We've learned from Evo Devo (thx PZ!) that multi-cellular anatomy is all about regulatory changes. Novel genes, and new combinations of existing genes, do make new cell types possible. But new anatomical structures (the actual shapes) are created largely by regulatory changes.
My point, however, is that even a gradual sequence of regulatory changes, forming a novel structure, can't possibly become fixed in 30 generations. So it was likely a single regulatory change, a major switch, that turns the whole structure on and off, that became fixed.
... just to be clear, the mechanism serving as the source of variation, whether a mutation in a gene, a regulatory gene, localized epigenetic effects, or whether we just see fixation of a pre-existing gene from a founder effect, do nothing at all to imply that selection did not play a role in what we end up seeing phenotypically in the new population.
In fact, selection has played a rather obvious role in this case, regardless of the source of variation.
windy:
The point you made is, more or less, the point I'm making here too. And that point is that we are probably not talking about "an evolutionary novelty, a brand new feature not present in the ancestral population and newly evolved in these lizards". Not on genetic level, in the "classic" ID-sense, anyway.
But I'll be very interested to see PZ's response.
This is cool, but:
1. We don't a priori know if this is a new mutation, or if it was present at a low frequency in the native population. Any info on how simple the genetics for it are? Single gene? Recessive or Dominant.
2. I am also concerned it could be non-genetic. If one force fed a vegetarian diet to another sub-population of the native population lizard, and threw in some soil teaming with nemotodes, might one get as a matter of development, cecal valves and guts swarming with nematodes?
Cuttlefish, OM
One of my faves to date. You amaze!
I think your assumptions about minor changes are a bit off... it's not that lizards arrive on island 30 years ago, wait for first novel mutation, let selection fix that, wait for next novel mutation, let selection fix that, and so on. As I said, selection can bring about the fixation of novel combinations of existing genetic variation.
So it was likely a single regulatory change, a major switch, that turns the whole structure on and off, that became fixed.
that's certainly possible (again, without looking at the actual paper, I have no idea what level of genetic analysis they have done). However, what you are proposing here has nothing to do with a founder effect. Are you perhaps misunderstanding what that means, or are you now moving on to a different idea?
regardless, again, a simple analysis of the genetics of the population compared to the parental population would easily resolve the issue, and it would surprise me if the authors had not already done (or quickly plan to) do this themselves.
As it is, right now, the development of a cecum in THIS species IS novel, and I rather doubt anyone would argue that the appearance of it has nothing to do with selection.
as to the MECHANISM that produced it, I'm just repeating PZ at #50:
in the "classic" ID-sense, anyway.
HUH?
there is no "classic" ID anything.
hence why you obviously felt the need to put it in scare quotes.
I suggest you dump what doesn't apply at all.
You have some interesting questions, and all you are doing by introducing ID is confusing the issue.
...unless you have some specific testable prediction born of IDeology that would somehow apply?
no?
thought not.
Even if nematodes somehow did provoke cecal ridges in a population, that doesn't explain how that population would then pass them on to their descendants. It's like the old idea that giraffes had long necks because their ancestors stretched theirs to reach the highest branches of the tree.
That idea is called Lamarckism, and while it was accepted for a time, faute de mieux, it was replaced as genetic mechanisms of inheritance became better understood.
#176:
The point you made is, more or less, the point I'm making here too. And that point is that we are probably not talking about "an evolutionary novelty, a brand new feature not present in the ancestral population and newly evolved in these lizards". Not on genetic level, in the "classic" ID-sense, anyway.
No, that's not what I mean, I mean that it doesn't have to be 100% brand spanking new genetic information for the stucture to be a novelty. I don't know why we should define this on the ID'ers terms, especially because they usually are unable to define anything.
I am guessing you are worried about "overselling" this example, if it later turns out that no new mutations were involved? But that's easy, just don't call it "new genetic information", call it a "new structure".
But I'll be very interested to see PZ's response.
uh, just to repeat, see #50.
However, I'm curious as to why you think PZ's response would be of specific interest?
However, what you are proposing here has nothing to do with a founder effect.
Yes it does. I'm not only suggesting that a single genetic change became fixed in the population (instead of a whole sequence) to make the cecal valves visible in the phenotype. I'm also suggesting that even this single substitution was probably further helped by the "founder effect", i.e. that the regulatory change enjoyed a much higher frequency in the child population than it enjoyed in the parent population. Initial frequency has a major effect on fixation time.
Regardng woelfel @ #121:
Let's keep in mind Poe's law here: it was parody, don't you think so?
Founder effects are due to chance. Why should the founder effect have happened to fix a structure the lizards needed to thrive in their new environment?
I'm not only suggesting that a single genetic change became fixed in the population (instead of a whole sequence) to make the cecal valves visible in the phenotype.
this is a completely different issue than the founder effect. Moreover, there were many other phenotypic changes in the population as well, not just the formation of new cecal valves. It's possible (actually I'm not even sure it is) they are all related to the same changes in the same regulatory genes, but that at least seems rather improbable.
Initial frequency has a major effect on fixation time.
THAT is a prediction of the founder effect, but is unrelated to your second issue. You need to tease these two things apart.
As I have said several times now, that would have been a very easy thing for the authors to control for, and still COULD likely test for if they hadn't.
I guess I'm missing what your overall point is? is it just to argue with this line from PZ's original post?
Evolution created something new, and it did it quickly (about 30 generations), and the appearance was documented.
As both windy, I, PZ, and others have pointed out, the production of a novel structure can arise from a number of different pathways. That is indeed the interesting question to ask at this point, and nobody (including the authors) is saying otherwise.
Windy: I am guessing you are worried about "overselling" this example
Exactly. And now I've been notified by you and others that PZ kinda has already made it clear that he's concentrating on the phenotype. Fair enough, but then it will be of limited interest to his favorite villains. Also, until we know the genetic background, this example might turn out to be downright bogus. It might turn out to be an example of "co-option" (existing genes combining in a novel way to form a new structure, a true phenotypic novelty, in a woosh), like I think you suggested. But it might also turn out to be just an old trick re-awakened before it got destroyed beyond repair by drift, like I've suggested. (And I kinda think you, too, find my hypothesis more likely?)
Also, until we know the genetic background, this example might turn out to be downright bogus.
no, knowing the background would be interesting, but would hardly make the observed changes in the population any less relevant.
(And I kinda think you, too, find my hypothesis more likely?)
at this point, you haven't formed a hypothesis.
shit, or get off the pot, as they say. I rather suspect you of being deliberately obtuse.
I also suggest, before you continue, that you be sure of your terms and actually read the paper before you go totally off the deep end.
I understand evolution at the basic level to be a change in the genetic makeup of a population. I haven't read the original article but have read the Science Daily news release, and several blogs. I didn't see that the authors had data for, or argued for, the new population being genetically different than the parent population. It is possible that the parent population had the morphological and behavioral plasticity to adapt to the new situation without change in genetic makeup. If so, we are seeing adaptation without evolution as defined above. I suspect there have been genetic changes, however.
I recall a study of a cichlid fish which had massive molar pharyngal teeth for crushing snails. Some babies were raised in aquaria and fed on non-hardshelled food. These fish developed quite nicely, but had your usual-looking pointy cichlid pharyngal teeth.
No one claimed it was the result of a novel mutation -- I'd actually be very surprised if it were (although new mutations may well have contributed to the phenoytpe). I expect this is the result of selection for novel combinations of alleles in the founder population, plus developmental plasticity.
So what? THAT'S EVOLUTION, TOO.
Why should the founder effect have happened to fix a structure the lizards needed to thrive in their new environment?
hence why I brought up the fact that a plethora of phenotypic changes have occured, all of which point towards a common set of selective pressures.
again, I'm still unsure as to what Esko is really driving at.
this IS a great (and fun!) example of evolution in action, all the moreso because it generates interesting questions as to the particular mechanisms involved in generating the variation.
Far from being the "possibly poor" example Esko seems to imply, it's actually quite a good one.
I rather suspect you of being deliberately obtuse.
Nah, he's just a stubborn Finn :)
Thank you to everyone who responded to my post above.
I agree that there are many disanalogies between a drunk blindfolded man stumbling around and random mutation plus natural selection.
However, the point of my analogy was merely to show that just because a particular process can produce results within a narrow range, it doesn't follow that it can also produce results outside that range. Natural processes are limited in their power, and the process of random mutation + natural selection is no exception. It is simply incorrect to point to examples of RM+NS producing microevolution (finch beaks, antibiotic resistance, and so on), and then just assume on that basis that RM+NS is also realistically capable of producing the most spectacular types of macroevolution as well.
Now people will point out the large time scales involved here, and say "Look, just extrapolate from observed microevolution over those timescales". But what is the reason to think that RM+NS could realistically produce spectacular macroevolutionary changes even over the very long time scales in the history of the earth? It seems to be nothing more than an appeal to intuition i.e. "It sure seems like in all that time macroevolution could be produced by RM+NS". To which I reply: well, *maybe* it could, but there is no reason to think our intuitions are reliable when it comes to deciding what is or is not plausible over long time scales.
I think the evolutionists are being far, far too optimistic in their assessment of the power of RM+NS, even over long time scales. More likely, they have no option but to think RM+NS and similar processes were responsible, because they are committed to naturalism to begin with, and this is the only naturalistic explanation that has any hope in hell of succeeding.
I conclude that it is fair enough for IDists and creationists and agnostics to suspend judgement about whether or not RM+NS can realistically produce macroevolution. Until this can be shown, the default position on the origin of species is what it has always been: I mean, don't those organisms just LOOK designed? :-)
Just one more explanation about the founder effect. Fixing even a single genetic change in a population takes some time, and 30 generations is in fact a rather small chunk of time. However, assuming an unusually high initial frequency would greatly cut the fixation time. The founder effect, rather obviously present in an initial population of 10, grants just that assumption. Additionally, we can assume that possessing a cecal valve is indeed a crucial matter of life and death for lizards on Pot Mrcaru.
Nah. Lizard densities are now higher, and the P. sicula in question are omnivorous, with insects >40% of the diet.
Yeah, but these lizards are also not very good at catching them: and their legs are shorter and they are slower
The founder effect, rather obviously present in an initial population of 10, grants just that assumption. Additionally, we can assume that possessing a cecal valve is indeed a crucial matter of life and death for lizards on Pot Mrcaru.
I would highly suggest you spend some time reading the literature on ACTUAL cases of how the founder effect works in the field.
Additionally, we can assume that possessing a cecal valve is indeed a crucial matter of life and death for lizards on Pot Mrcaru.
but the point I can see of suggesting a founder effect in this case is to assume that there NEED NOT BE a strong selective pressure to cause the fixation of a trait (that is usually the reason the founder effect is suggested, btw).
so, again, I fail to see what your point in proposing it is, since there is, by your own words, there is indeed a very strong selective pressure.
Moreover, the many other phenotypic changes do not suggest a founder effect is involved.
so, I rank the probability of a founder effect being the primary mechanism for the total package of observed phenotypic changes as being relatively tiny.
However, assuming an unusually high initial frequency would greatly cut the fixation time.
Selection would also cut down the fixation time without the need for a high initial frequency.
Think about dog breeds. Or the tame silver fox. Would you conclude that the phenotype of the tame silver fox must be due to a single regulatory mutation, which was present in the initial population in high frequency, since 30 generations is too short a time to fix multiple changes by selection?
so, again, I fail to see what your point in proposing it is, since there is, by your own words, there is indeed a very strong selective pressure.
What if you have a million people drunk and blindfolded, trying to get across New York City on foot? What's the chance that several of them will make it, especially if everyone else is drunk and blindfolded?
I'm about to leave work now, so I'll let you know how today's iteration of that experiment turned out.
I think the evolutionists are being far, far too optimistic in their assessment of the power of RM+NS, even over long time scales.
then it's a damn good thing we haven't relied on your strawman of modern evolutionary theory for decades now, right Hugh?
*rolleyes*
hah! take that!
suck it, creo-f**ktards!!!!
(man, refusing to appease idiocy is liberating!)
I haven't read the original article....
I didn't see that the authors had data for, or argued for, the new population being genetically different than the parent population.
I'm gonna owe Orac $5 but...
The Stupid, It Burns®
I'm about to leave work now, so I'll let you know how today's iteration of that experiment turned out.
LOL
do you find a large or small deviation from the average?
@Hugh Slaman: living organisms look designed in much the same way that the earth looks flat.
You may be looking at function and assuming it's design. A common problem.
I have no idea of biology whatsoever, never studied it. But I understood this short article, at least to a satisfying degree. Thanks for making these new and interesting discoveries understandable for me, PZ!
I mean, don't those organisms just LOOK designed? :-)
I mean, doesn't your post just LOOK moronic?
hugh, imagine with me, that we make a change per 10 years.
Now, let's give it a million years. We have 100,000 changes. Now, give it 3 billion. 300,000,000 changes.
The changes accumulate, you know. And those that help them survive better, will be more likely to be passed on.
These numbers are arbitrary, the reality is much much more complex than that, but, to say that small changes over time do not add up to larger overall differences is like saying that you can walk to the kitchen, but it is absolutely impossible to walk to the store.
Has anybody pinpointed the protein or regulatory evolution that evolved the new gut?
This is so interesting! I love reading stuff like this. Biology isn't even my "thing," but... wow. Nature. Every time I read something like this, I feel sorry for the silly folks with their imaginary friends who won't stop and look around at just how freaking cool the universe is.
But on a practical note, just because they've adapted to a new diet, I still save money on my car insurance, right?
I know, this is really the golden age of biology, and most of the new research is meaningless without evolution (I mean evolution, not repeated interventions by a deity).
I really wish someone in the media would point out this fact. Physics isn't producing the wild developments that it used to do, and chemistry has most of the basics down already. Physics will pick up if it ever finds the evidence for string theory or some other "theory of everything," but right now it's kind of quiet.
Cosmology and astronomy are booming with discoveries, and so is biology. Why? In large part it is because there are many holes in what we know, but these are holes that are relatively easy to fill (unlike some of physics' problems), and they are indeed being filled rapidly. I mean that basic questions of evolution remain to be answered 9not including the fact of evolution, certainly), like whether there really was an RNA world, the relative effects of various evolutionary mechanisms in eukaryote evolution, and exactly what is related to what else (though of course the main trunks of more recent evolution change little, if at all).
This is a fantastic time of discovery in the branch of science most directly interesting to most living humans, and yet many are simply trying to prevent this knowledge from being accessible to others, including the entire next generation of children--well, they would if they could.
Glen D
http://tinyurl.com/2kxyc7
Sorry, but you guys seem to get purely argumentative here. This is my last post about the founder effect. By no means let this stop you from responding again and again. And I'm sure you won't.
Windy: Yes, you can create hypotheses of wild selective pressures, in principle. I in fact granted you just that possibility in the last sentence of my post, so that you wouldn't have room for wise cracks. But of course they had to be said all the same. Because of course there was something analogous to breeding going on on Pod Mrcaru. And because of course an artifical crossbreeding of several separate traits is analogous with evolving gradual and cumulative changes in the same trait. Hey, multiple is multiple is multiple -- anything else is probably nitpicking, right?
Ichthyic: but the point I can see of suggesting a founder effect in this case is to assume that there NEED NOT BE a strong selective pressure to cause the fixation of a trait (that is usually the reason the founder effect is suggested, btw).
Well, change the word "additionally" to "alternatively" if a strict dichotomy helps you to avoid confusion. Although I see no sensible reason why the founder effect and high selection pressures could not be combined in various degrees, including as strict alternatives to each other, to account for unusually fast fixation times. But then, it must be that in ACTUAL cases on the field only strict dichotomies were observed to work. Or - maybe not (says humble common sense).
there is, by your own words, a very strong selective pressure
I seem to be unable to find those words of mine. Although I still grant that one can always resort to extreme selection pressures.
so, I rank the probability of a founder effect being the primary mechanism for the total package of observed phenotypic changes as being relatively tiny.
Great. But what does that have to do with me? Nothing. I've never talked about any other trait than the cecal valves, which are actually reported to be fixed in the population. I have consistently, but at the same time very confusingly I'm sure, scoped outside my interest the various changes in average measures that can be quite trivially explained by mere changes in the original allele frequencies of the population. No fixation of alleles related to these traits is needed and none is claimed by the article. Darwin's finches are known to even oscillate this way.
There's an interesting thing about the drunk blindfolded people not making it very far. There is a mechanism preventing them. They will be sick, or pass out, or just get tired.
However, no such mechanism exists to stop "micro" evolution from becoming "macro" evolution. Unless you can find one, in which case you might win a Nobel prize. Otherwise, drunk, blindfolded perpetual motion machines is all you need for a decent analogy of genetic drift. Add a selection process like someone yelling out "warmer, colder" and you could get anywhere with that.
#182 confuses the common real issue of developmental and morphologic plasticity with Lamarkism.
What I raised in #177 is a real issue, apparently raised by the authors as well as PZ in #50.
I bring this up because the fact that environment can play a real role in shaping morphology, both in selective activating of genes and in more simple direct effect on the organism, is often confused with Lamark... it's only false Lamark if that environmental effect then directly causes permanent genetic changes, e.g., the classic false example of positive feedback loop in giraffe's stretching their neck, yada yada.
I think the case for evolution is even stronger.
No one saw the other lizard die off....my "theory" is that they were getting out-competed so they evolved into birds and flew away.
:-)
You ain't got no inner lizard. The lizards are more closely related to the birds than to the mammals.
Our ancestors 300 million years ago did superficially look a lot like monitor lizards, though.
Um, WTF? We have indirect evidence for selection pressure (the morphological changes are correlated with ecological changes) while there is so far no evidence that cecal valves are present in the original population. In particular the hypothesis that several of the 10 founders must have had cecal valves is entirely pulled out of your ass.
Again, WTF? Wisecracks? I'm just asking you why you conclude "founder effect" for the lizards, but not for the foxes? Or do you? There is no "crossbreeding of several separate traits", there's selection for a single trait with correlated changes in other traits. Read up on the experiment, it's quite fascinating.
Esko, don't be stupid. We are saying that the founder effect is entirely unnecessary, superfluous, unparsimonious as an explanation a strong selection pressure. If there isn't a selection pressure, why does the presence of cecal valves correlate with the new diet?
... that should be: unparsimonious as an explanation if there is a strong selection pressure.
Although I see no sensible reason why the founder effect and high selection pressures could not be combined in various degrees, including as strict alternatives to each other, to account for unusually fast fixation times.
NO, you're missing the point. Why assume the founder effect is operating when there is an obvious match to local selection pressures that are paralleled not just in the appearance of cecal valves, but in the other changes as well?
You isolating one change from the others simply makes no sense.
I'm thinking windy was underestimating the "stubborn Finn" angle.
I seem to be unable to find those words of mine.
well, let me help you:
Additionally, we can assume that possessing a cecal valve is indeed a crucial matter of life and death for lizards on Pot Mrcaru.
I even quoted it twice in response (#199)!
sure sounds like a strong selection pressure to me.
At this point, I think you have lost track of your own argument, and I have grown past caring to try and figure it out.
Everyone's on the wrong track. What they need to do is find the point in the past 30 generations where God intervened directly upon the lizard population - placed the caecal valves, shortened the legs, slowed the reactions, depressed the territorial instincts, and expanded the skull region. And probably left a few little tricks for further generations down the track.
And he thought "THAT'LL fox those nasty so-clever biologists like a kid called Myers who will one day become the Means Of My Destruction but lo! I shall prevent it by intervening directly with lizard populations on isolated islands, and my mouthpieces shall be called IDeators and they shall spread the word of my intervention.".
And then said to the lizards "Go forth and from this day hence, be more vegetarian than insectivorous". And he saw his Creations, on a nice micro scale, and it was good.
(Note: post may contain traces of facetiousness).
Lamarck, actually. Basics again, Steve.
You're the one who used the term "non-genetic". If you had actually said "epigenetic", you would have been conceptually closer to actual ongoing research, but your example is still closer to classical Lamarckianism than it is to what epigenetics actually is.
Course, if you have any actual evidence that nematodes can induce heritable gross anatomical structures de novo in lizards, we'd love to see it. But most of the epigenetic literature focuses at more granular levels than gross anatomy, such as cell-cell interactions or metabolic pathways, so there's not currently a lot of evidence for such a scenario at the gross level. If you have any, though, let's see it.
Yeah, I thought it was you from the 'nym, but decided as long as you were going to be civil, I'd interact with you civilly. Guess you just can't not be yourself, though.
What they need to do is find the point in the past 30 generations where God intervened directly upon the lizard population - placed the caecal valves, shortened the legs, slowed the reactions, depressed the territorial instincts, and expanded the skull region. And probably left a few little tricks for further generations down the track.
sounds great.
uh, you first?
:p
I apologize if this has been addressed earlier..
I'm an atheist who firmly supports the theory of evolution, so, don't mistake my meaning, but...
Could anyone explain what kind of features would have led to these valves developing? My idea would be ridges in the gut that helped break down plant material, therefore individuals with ridges had a higher chance of passing on offspring until the ridges eventually developed into fully-formed valves?
/first-time commenter
So you're saying God is a liar?
As PZ said in the post that, I hope, you have read:
That's what's impressive.
Parsimony.
Look, what is supposed to stop RM+NS+random drift from producing "spectacular macroevolutionary changes" if enough time is available? How can that even be avoided?
(Without God working a miracle, I mean.)
Comment 215 says it nicely.
Two words: Stupid Design.
Last time I read something about them, beak length was fixed in Darwin's finches, and oscillated with the climate between El Niño and La Niña. Has that been overturned???
Yes, that's exactly the kind of study that could provide evidence that would point to the possibility of epigenetic influences. Tomorrow, when I'm in the lab and have library access, I'll get the paper and read it. It will be very interesting to see whether the authors talk about possible epigenetic implications in the discussion.
Nobody knows. Sounds like a Ph.D. thesis in developmentary genetics for someone...
Fair enough.
It is so obvious now! T. rex must have lost its cecal valves (needed to digest its diet of coconuts) after Adam and Eve sinned and were cast out of paradise.
http://www.scientificblogging.com/fish_feet/t_rex_ate_coconuts?page=5
"In Genesis 1:30 God gives 'green herb' to every creature to eat and so there were no predators. When a curious museum visitor asks, why exactly T. rex had six-inch long serrated teeth, the guides go on to explain that T. rex used his big teeth to open coconuts. Apparently it was only after Adam and Eve sinned and were cast out of paradise that the dinosaurs started to eat flesh."
I think I've observed a sort of evolutionary adaption of small lizards here in north Texas to the imported red fire ants. I should preface this with the fact that this is a purely subjective unquantified impression or observation of something that is actually probably quite quantifiable. Prior to the wide spread of fire ants across the southern US, small ground dwelling and ground nesting lizards were more abundant than they were after. Again no hard data, but many people, old timers mainly, have told me that this was the case. Lately, I've seen more American anoles, and a worm-like ground skink. I think they are evolving to be able to live with fire ants better and better each year. Their feeding habits and egg laying must be moving them away from vulnerability to the imported scurge of fire ants. The lizard most missed here in Texas is our beloved Texas Horned Lizard, aka horned frog or horny toad. It used to be abundant all over the state, but now is common only in the western half of the state, which is also where it is generally too dry for fire ants, unless there is man made source of water nearby. Being ant eaters, they were very badly affected by the fire ants, since they venom in one fire ant bite could kill a horny toad. Horny toads like to eat the big black harvester ants, which have rather weak venom. Fire ants are also a type of harvester ant(grease seeking seed eaters), so they were also badly affected by competition from fire ants, plus all of the man made efforts to eradicate the fire ants, all of which failed. The good news is that he parasitic flies from Argentina seem to be working at least in southern Texas, and there are some new virus disease specific to the fire ants that may also help control them. I love these cute little lizards, even the non-native house gecko's on my window screens.
You know, chuck, a lot of data in the natural sciences traditionally has come from dedicated amateurs (from the Latin root for "love", for someone who follows a pursuit out of love for the subject rather than money/professional). Birders and amateur astronomers are two modern examples that come to mind immediately.
You could formulate your hypothesis, and go on to collect data to check it out, but even if you don't do so, it's really gratifying to see someone carrying out the steps of scientific thinking in observing everyday life. I think amateur scientists aren't always adequately recognized and encouraged, so just wanted to register that.
That is so. It would take at least 2 billion years from the first eukaryotic cell to evolve outer space traveling, tool using, TV watching, intelligent beings.
Hmmm, how long did it take us? Checking......
Gee, the first eurkaryotic cell appeared about 2 billion years ago. I'm sure that is just a coincidence.
As for the hypothesis advanced here that the nematodes might have something to do with the genetic changes, I've seen research hinting at using c. elegans and its kin as delivery vectors for GM, but surely they would have had the same effect on the previous species?
Hornytoads vanished long before the fire ants came in and are now absent in areas of Texas the fire ants haven't yet reached. I think I read somewhere that they got hit by a form of malaria. I have both fire ants and ground dwelling lizards on my place south of Austin, so some accomidation seems to have been made. Incidentally, hornytoads do squirt blood from their eyes. I've seen it happen.
I remember reading something similar about population declines of the Coast Horned Lizard in California. Argentine Ants have been replacing the native Harvester Ants with a negative affect upon the lizards.
Incidentally, hornytoads do squirt blood from their eyes. I've seen it happen.
last post for tonight, as something unkown (I suspect a faulty router) is seriously hindering my access to sciblogs this evening.
Phrynosomids actually do exhibit some variability in which ones expel* blood from their eyes.
http://www.desertusa.com/april96/du_hliz.html
I can't recall ever seeing a study that looked at whether there was a pattern to which species did or did not exhibit it, though.
I haven't done a thorough search, but I'd say that would be quite a worthwhile amateur project.
*heh, sorry, couldn't resist even a fraction of the word going without linkage.
This study found a newly aquired symbiotic relationship. With all the comments about plasticity and a new vegetative diet, I only found the nematode factor addressed in three posts. #177 DrSteveB speculated that they were picked up from the soil, and inferred they might be a factor in the cecal ridge development. #182 thalarctos questioned how later generations of lizards would acquire nematodes. #235 wazza mentioned nematodes as vectors in GM and wondered about their role in the extirpated P melisellensis on Pod Mrcaru.
Gut dwelling symbiotes are often transferred by the young hosts eating the feces of their elders. Fence Swifts can be observed touching their tongues to lizard feces. Although the nematodes could originally be soil dwellers, it seems more likely that they were aquired by the newly introduced P sicula from feces of the original P melisellensis Mrcaru, already preadapted for living in lizard guts.
The article does not mention if P melisellensis is also found on Pod Kopiste. Does P melisellensis normally have a diet richer in vegetation than P sicula? How does a typical P melisellensis compare to a typical P sicula? If P melisellensis favors a plant diet and has a heavier build, then the newly developed robust P sicula Mrcaru morphs would have taken over the previous lizards' ecological niche and assumed its adaptations and symbiotes for this new role.
I just remembered that Horned Lizards are part of a life cycle with an intestinal parasitic nematode which are often expelled in the lizard's feces. Ants gather the dried nematodes from the feces and bring them home to feed the colony which ends up ingesting nematode eggs and becomes infected with the worms. Infected ants are then swallowed by foraging Horned Lizards. Repeat.
So do those nematodes in the P sicula Mrcaru gut play a positive or negative role? Or are they just along for the ride?
This is what I love about science, one discovery invariably opens up so many other possible lines of investigation. I mean, just look at the questions worthy of someones PhD that have arisen in this thread discussion alone. I just wish I had another lifetime ahead of me so I could go back to school and start all over again, but this time in the biological sciences.
#96, by Dutch Delight, April 23, 2008 12:56 PM:
I may be missing a joke, but Lamarck ≠ Lysenko. (Atheist yes, Commie no.)
"Maybe god just thought they needed a cecal valve because of their new habitat. Just like he thought we needed to have shellfish fossils on mountain tops to confuse us, so he put them there. It's not that difficult people."
Are you saying that God put shellfish on top of mountains just for a laugh?
You are ridiculous.
it's bullshit.
To the contrary. They are pure insectivores, while P. sicula is omnivorous, as explained in one or two comments way above. Surely you didn't comment without reading all previous comments?
They do most of the digesting, apparently.
Deliberately so. It's satire.
Thank goodness
:D
Thank you, Pete. This is my new favorite answer.
You are correct, comment #52 states that P melisellensis is insectivorous. #99 looks at the interesting situation of an insectivore being outcompeted by an omnivore trending towards a more herbivorous diet.
Windy: In particular the hypothesis that several of the 10 founders must have had cecal valves is entirely pulled out of your ass.
Otherwise I will stick with my promise to not continue this useless topic. But I can't resist replying to this wise crack.
I wouldn't want to pick up a soap bar from the floor next to a guy who can't distinguish my ass from his own! :) You, too, are free to think in terms of dichotomies, if you must, but don't stick them into my orifices and then pull them out as if they were mine.
I've never discarded or even momentarily questioned selection in all possible intensity options. I have just provided an option to extreme selection -- another thing I've never assumed but only admitted that it can be assumed, and apparently is embraced without scrutiny by at least windy. (It's funny how you and Ichtyic seem to fully agree even when you contradict each other in your guessing games about what I supposedly claim. Must be the magic of matching friend-or-foe signals.) I've merely pointed out that a high initial frequency would help to fix an allele unusually fast without needing to resort to extreme selection. (As in, "originally present in one of the ten individuals", see my original post. Now whose butt are we staring at, eh?) A single copy of the allele would be quite sufficient to do this as long as we consider the founder population of 10, because v0=0.05 (or 1 out of 20 diploid slots) is, in fact, a high initial frequency for a substitution. It is not a necessity (as in "must") but in my view a rather plausible possibility (as in "perhaps", see my original post).
But luckily we know from artificially accelerated substitutions in breeding that fixation times in the wild never require no scrutiny, either. The little buggers might, say, have probed for a funny gut in their mating schemes to speed things up.
First, it is known that DNA has the ability to restore previously 'unexpressed' functions and mutational damage by resorting to "an ancestral RNA-sequence cache":
"Here we show that Arabidopsis plants homozygous for recessive mutant alleles of the organ fusion gene HOTHEAD5 (HTH) can inherit allele-specific DNA sequence information that was not present in the chromosomal genome of their parents but was present in previous generations. This previously undescribed process is shown to occur at all DNA sequence polymorphisms examined and therefore seems to be a general mechanism for extra-genomic inheritance of DNA sequence information. We postulate that these genetic restoration events are the result of a template-directed process that makes use of an ancestral RNA-sequence cache." http://www.nature.com/nature/journal/v434/n7032/abs/nature03380.html
"Here, we show that a rice triploid and diploid hybridization resulted in stable diploid progenies, both in genotypes and phenotypes, through gene homozygosity. Furthermore, their gene homozygosity can be inherited through 8 generations, and they can convert DNA sequences of other rice varieties into their own. Molecular-marker examination confirmed that this type of genome-wide gene conversion occurred at a very high frequency. Possible mechanisms, including RNA-templated repair of double-strand DNA, are discussed."
http://www.ncbi.nlm.nih.gov/pubmed/17502903?ordinalpos=1&itool=EntrezSy…
Second, modifications in chromatin can 'deactivate' genes, but changes can also be reversed that can cause functions to reappear:
"Changes in gene expression can result from modifying chromatin, which is the structure comprising proteins and DNA that is the repository for genetic information. Marks are imposed that serve as templates for modification of the chromatin, altering the ability of genes to be accessed by the DNA transcription machinery. The result is that some genes are suppressed and others are silenced altogether. One of the key questions discussed at the ESF workshop concerned how these changes are "remembered" during cell division through replication of the epigenetic marks, and yet how in some cases these can be reversed, allowing a cell to be reprogrammed so that it can take on a different role or function."
http://www.physorg.com/news127045681.html
"Eggs incubated at higher than normal temperatures of 93.2 to 98.6 degrees Fahrenheit (34 to 37 degrees Celsius) produced a strong bias toward female hatchlings, which outnumbered males by about 16 to 1.
The researchers linked this gender bias to a sex-determining gene that was deactivated when the lizards' nests became unusually warm.
This process results in female offspring, because the key gene is on the so-called Z sex chromosome, of which male lizards have two and females only one.
Deactivation of the gene therefore turns a male (ZZ) into a female (WZ)."
http://news.nationalgeographic.com/news/pf/97933756.html
Third, if indeed this is a case of a new feature that was "not present in the ancestral population," evolutionists must face the persistent problem of convergent evolution. Regardless of all the evolutionary excuses for the 'evolution' of identical features in unrelated organisms or, in this case, an isolated population, identical features arising in unrelated populations is an absurd premise. Of course, unless you believe in the supernatural:
http://www.whoisyourcreator.com/common_descent.html
I assure you your ass is safe as it would be anatomically impossible for me to perform what you imply...
I don't think 0.05 is a "high initial frequency", so I assumed you updated your hypothesis from "one individual" to "a high frequency".
But if the cecal valve were the result of selection on quantitative genetic variation already present in the founders (as PZ also suggested), all the relevant alleles must also have been present in the founders at a minimum frequency of 0.05! So I don't know why you conclude that the one gene example is more likely and several genes would require "extreme selection". Please show your work.
No, what we know from the fox example is you can't look at the end result and say "wow, that can't be the result of selection on several genes, since 30 generations is too short a time, it must be a single regulatory mutation + founder effect".
Far from being absurd, convergent evolution is actually a logical prediction of evolution by natural selection correctly understood.
Cecal valves are unknown for the entire family Lacertidae, with the exceptions of the specialized herbivore Galliota and now this insular population of Podarcis. It's a bona fide new morphological structure. Deal with it. There is no evidence here to support a role for the founder effect. In fact, all speculation about the genetic underpinnings of the valve (or the short legs, or the changed skull shape, etc.) is at this point pure speculation. (This is also true for almost all morphological structures of almost all organisms.)
Nematodes are key here--like all amniotes, Podarcis is incapable of making cellulase. The only way they get any energy out of their plant diet is courtesy of the cellulose-digeting nematodes. The function of a cecal valve is to slow down gut passage rate to give the nematodes more time to digest plant material.
Yes the lizards are shorter-legged and slower, but they are still managing to eat a lot of insects.
What natural selection can and can't accomplish in the time available has been mathematically modelled to death. Start with G.G. Simpson back in, what? 1944? Really, ignorance is boring. Learn something before commenting please.
The decline of Texas horned lizards is poorly understood, but is very unlikely to be due to malaria or red imported fire ants.
whoisyourcreator, #250:
You realize, I hope, that paper is exceedingly controversial.
From a review of the paper by Alejandro Sanchez-Alvarado of the University of Utah, found here if your library has access:
Hugh Slaman, #196:
What about the genetic evidence? With more and more organisms having published genomes, it's becoming increasingly easy to compare the sequence divergence of single genes across species. It will become easier to compare the sequence divergence of entire genomes (including regulatory regions) across species as the technology for sequencing becomes cheaper.
We don't need to rely on intuition when we have data. That's what differentiates us from cdesign proponentists.
Anatomically true, but don't forget that nowadays we have the prosthetic technology....
PS:
Hey, don't make me write "Esko Heimonen nolasi itsensä" :) I know from sfnet.keskustelu.evoluutio that you're not a "foe". But you have claimed a number of unrelated things here which together are a lot less parsimonious than the hypothesis of rapid selection. Like persistence of cecal valves "from the ancestor of the genus or family" for millions of years followed by their sudden disappearance in the parent population in 30 years!
OK, developmental biology is about my weakest area, but one thing strikes me here.
I searched for cecal valve and got a lot of hits on Ileo-cecal valve in humans. Apparently it is similar to valves elsewhere that keep the contents of one part of the gut, the stomach say, from leaking into another.
I would assume that lizards have valves at least somewhere in their gut right? So could this be a homeotic mutation?
Sven #152, sorry that you're bored, but showing ignorance by posing questions here can result in informed answers. Thanks for sharing your knowledge.
Doh!, #252
Dave, Sven's a long-time commenter here, who's always generously shared information at a number of levels with a great deal of knowledge and wit. I read his "ignorance is boring" as targetted at creationist trolls, not at students genuinely seeking knowledge.
Making such an asinine, elementarily wrong, and easily refuted blanket statement like:
is not at all the same as genuinely asking a question in the hope of gaining new knowledge. I think you'll find people who do the latter are treated kindly and patiently here, as Sven has done on multiple occasions.
There's no reason to waste that effort on trolls who've declared their intention not to take in any information that challenges their already made-up minds, but they're not the people you're talking about anyway.
thanks, t.
Dave, my comment was directed at the "not enough time for NS" statement, not at anybody asking questions.
Thanks. You sure do have to sort the wheat from the chaff here.
I'm really curious about the origin of those cellulase producing nematodes. If P melisellensis Mrcaru was strictly insectivorous, then it seems doubtful that they would've had guts full of the things. Googling Pod Mrcaru and tortoise did me no good for what that's worth. I question soil dwellers as a source. Maybe plant eating birds?
RE: Mena #135 Thank you for admitting the falacy of this 'evolved' lizard valve claim, saying, "we both know that's not going to happen " re: my #121- finding all the lizards that lived during the years in question and checking presence of latent lizard valve genes]. You people neglect the obvious requirement for this theory to be shown as fact simply because it can't be shown. The onus is still on you to back it. Again, until it CAN be done this blog string is not based on facts but floats atop your collective faith. You all prejudge that the valve developed not on needed scientific evidence but instead you vacantly predetermine NO latent genes were present- the theory requires relentless faith. Please understand this is no average faith you guys are sporting... it's an enormous leap to assume brand new valve DNA came from ah, er where? Wait Oh I remember... it happened LIKE THIS: eons ago deep in the ocean, iron ore began to accumulate and form into sheets, the sheets developed holes and then came rivets; soon by this elusive process, a fully formed ship floated into harbor...what part of design troubles you people, it's everywhere you look- animate and inanimate!
Consider: Where there is a watch there is watch maker... where there is a world there is a worldmaker!
To date NO NEW DNA has ever been demonstrated to have jumped upwards into more complexity since mutations are always only a scrambling or loss of already existing DNA of offspring. A great deal of science has been accomplished since Darwins archaic sciencless dreams. Science is provable, testable and duplicable, at least be honest among yourselves and classify your conclusions of this type discovery accurately, it is conjecture.
For evidence for Noah, Adam, Eve, Cain, Abel; Mena, you candidly asked "We want to be able to test all of those, can you do that? Otherwise we can't believe in creationism, sorry."
To help you and other sincere minded individuals to believe in a Loving Creator and the subsequent tragic fall of man, you may look at Noah's ark remains at www.covenantkeepers.co.uk And www.arkdiscovery.com
The Turkish government has set up a tourist center over looking the 500+ foot ark remains, in the mountains of Ararat. Also on the websites are numerous pictures and eyewitness accounts of the remains of ancient Egyptian Chariot wheels at the bottom of the Red Sea. As far as evidence for Adam et,al, these predated the flood and are likely in your gas tank. Well, I can't say for sure what organic remains of the preflood world changed to coal or into oil. It is good evidence for the flood though to see how the world's waterborn strata deposits often go hundreds and even thousands of miles uninterupted and without the erosive effects of rain as would be expected if the layers were layed down over the alleged millions of years. Also supportive of the creation model are oil and coal deposits found off shore and up to five miles down in what are now the oceans... we see no such new organic deposits are being developed today. Animals and plants dying on the surface quickly turn to soil no oil. Hope this helps!
Like I said ....
To illustrate your point, not even 15 minutes later, Michael chimes in with predictable canards that have been refuted numerous times here and elsewhere.
Which reminds me:
Not in the least, actually, if you really want to know. But I doubt you do.
Now, back to a real discussion:
Once I get to library access and the paper, I'll see if they address that particular question in it, and let you know. It may well be tangential to the main thrust of the paper, and publication real estate is often quite tight, so extra stuff, even interesting and significant info, doesn't always make in it. But it is a very good question.
Sometimes, the corresponding author is willing to field questions like that, so if it's not in the paper, it may be worth a polite email enquiry. I'd hesitate to post the corresponding author's email in this forum, though, without explicit permission. But once I get the paper (this afternoon, or tomorrow morning [more likely]), if that point's not addressed, I'd be willing to forward your question to the corresponding author, if that's ok with you (or send you the email from the paper itself to an email address you specify, if you'd prefer to do so yourself).
Slightly off-thread but on the theme of getting across a room in the dark after a few drinks there is a material risk that someone will have moved the door while you were unconscious and you end up in the wardrobe. I haven't yet experienced an equivalent problem walking around Manhattan* the few times I've been there. On that basis it might actually be easier.
(Although a friend did once in what was Leningrad at the time. Woke upon a concrete square surrounded by barbed wire, and wept because he'd never see his family & friends again. Later he discovered that he'd blundered into a building site.)
...and where there is a turd...
To the people wondering about the nematodes, this is all the paper says about them:
I love this stuff. Reading the comments on threads like this one is almost as good as (and a lot quicker than) auditing a class. :-)
Michael Woelfel, #252
I'd just like to point out for the lurkers that this is patently untrue.
Just in case it wasn't obvious already.
Also, I'd be happy to send the PDF of the paper to anybody who wants it -- my email is the same as my posting name, after replacing the "at" in the middle with "@" and adding ".edu" at the end. :)
PZ, the island was abandoned/ignored for 36 years. Can you prove Juju Man in the Sky didn't place these new fangled lizards there when no one was watching?
Hah! I thought not! :)
Fish with fins and scales, tra-la!
No auditing! There will be a test on the material at the end of the comment thread.
Sven DiMilo "and where there is a turd..."
There is a caganer! (As appears in scenes of the Nativity of Our Lord.)
http://en.wikipedia.org/wiki/Caganer
And therefore there must be a Divine Caganer - He isn't called God of the Gaps for nothing. Hallowed be his evacuation.
Carl worries the creationist evolution deniers will say
Oh, no doubt. But here's the kicker: In 37 years, to make that change these lizards developed more powerful chewing appparati and teeth to go along with a vegetarian diet, as well as modifications in its gut.
So, with vegetarian T. Rex, we should see some similar adaptations. Where are the fossils that show these vegetarian adaptations?
(Hint: Such fossils do not exist, for T. Rex)
So did they look at the amount of heterozygosity at some loci between the original founding population and the new species? If what I'm reading (and if my understanding is correct, but I am not a biologist), then would less heterozygosity be expected in the new species? I suppose this would probably have to be true just due to the fact that there were only 10 founders, so you were bound to lose some alleles? Would that allow a more rapid shift than in a larger population? (I hope that question makes sense.)
Not yet, they only looked at mitochondrial DNA (no heterozygosity 'cause it's haploid)
A bottleneck with 10 individuals and a rapid bounce back to original population size wouldn't necessarily lead to much loss of heterozygosity. Instead, rare alleles get lost.
Not as such, since more genetic variation generally allows a faster rate of selection. But sometimes things get weird and a bottleneck "exposes" genetic variation to selection. Peter Ashby's comment 136, point 4 describes that kind of situation.
Fish with fins and scales, tra-la!
ok, I think I've seen you post this a couple of times now.
what is it referring to?
...is it some obscure reference to Kosher fish?
Beats me.
Must be a Scandanavian cultural reference, not easily found untranslated... ;-)
windy,
Thanks for your response. I'm going back and digesting your comments about the founder effect as well. :-)
Must be a Scandanavian cultural reference, not easily found untranslated... ;-)
well, the reason I thought Kosher, is because a truly Kosher fish, by orthodox Judaism, must have both fins and scales.
just one or the other won't do, dontchya know.
Eels, for example, just ain't kosher...
Wow! Proof that the Intelligent Designer is still at work! ;-)
Ichthyic: Oh right, it was Lightning Rose who posted that (to this thread, and to the older thread), not Windy. I mis-read. It's probably wise to scratch the "Scandanavian" hyposthesis.
The "kosher" hypothesis is looking tastier by the moment.
Hey, don't make me write "Esko Heimonen nolasi itsensä"
Ha! Please, be my guest. It should be a healthy change of pace at that anemic asylum (s.k.evoluutio), where a couple of dozen evolutionists gather daily to stone a couple of creationist fruitcakes who can barely count their own toes.
Good news everyone!
Now that the civil war is mostly over, I need you to deliver this pile of snad to a small island off the coast of Croatia. Don't worry, the mutant lizards aren't entirely carniverous any more.
Fish with fins and scales, tra-la!
It has a nice cadence, does it not? :)
It comes from the Dover, PA, ID trial. As I'm sure you're aware, the IDiots like to claim that ID is not Creationism, but one of the pieces of evidence introduced by the plaintiffs was comparisons between earlier and later drafts of the book "Of Pandas and People".
"Creation is the theory that various forms of life began abruptly, with their distinctive features already intact: Fish with fins and scales, birds with feathers and wings, mammals with fur and mammary glands."
What was eventually published read:
"Intelligent design means that various forms of life began abruptly through an intelligent agency, with their distinctive features already intact: Fish with fins and scales, birds with feathers, beaks and wings, et cetera."
http://en.wikipedia.org/wiki/Kitzmiller_v._Dover_Area_School_District#O…
Eugenie Scott also uses the phrase repeatedly for humorous effect in her lecture, "Intelligent Design and YE Creationism".
http://www.youtube.com/watch?v=U3PnKswZtPI
http://www.youtube.com/watch?v=924Nz5WPxcQ
Oh, that's very interesting! I feel dumber for not knowing, yet smarter for being told! :-D
Trust me. I understand what it is like to talk to anyone without an open mind (both Christian and non-Christian). Evolution was a dirty word for me, until I started to see the evidence. It was shocking to my family when I told them that I wanted to study Evolutionary Theory (don't worry, no ond DIED of a heart attack). What may be surprising to many of you is that I still have not lost my faith (in God). I, however, do not expect you to believe (nor do I attempt to change your mind), since God cannot really be proven or disproven by scientific means. Evolution can be, though, so I accept it as a fact. I just say all of this to remind you that not all Christians (or those of other faiths) are mindless idiots. Growing up, I was taught that Democrats were lazy and stupid, but I know that that is clearly not the case, since I know just as many lazy and stupid Republicans. While I don't align myself with either party (since I really just care about the issue at hand, not what the label is of the person who is saying it) some of the people I most respect are Democrats and atheists (and I even agree with them sometimes! :) ). I am also around many people who believe that all Muslims are blood-thirsty criminals, and while this can be true (as it is for all other religious and non-religious people) some of the nicest people I know are Muslims. I also have a major gripe with the IDers, mainly becasue they are hiding their true intent - many of you have already guessed that this is not what Jesus would do (yes, that was an old slogan). Not all Christians are stupid and unreasonable. It just seems like the most vocal ones are.
Apparently, evolutionists can grasp at straws too. To say that the presence of cecal valves is an evolutionary development is very premature. It sounds as if it's merely a hypothesis (and one that hasn't yet been tested). Have they grown lizards from the parent population on the exact same diet (and habitat) to see whether they also develop cecal valves? They could also try to pinpoint the genetic changes (if any) that resulted in the development of cecal valves. In fact, without genetic evidence, I don't think you can say that any evolution has occurred. Let's be realistic: it's much more likely this trait was dormant, but not expressed in the original lizards. Your body responds to its environment according to its genetic program, and a lizard's does too. If this is the case here, the story supports ID: the genes are programmed so that the gut responds intelligently to various dietary conditions.
Wow. Just... wow.
Stupendously stupid.
I see someone up near the top asked about 'microevolution' proceeding into 'macroevolution'. Good question, especially right here. The answer has been around since Adam, but every now and then, people get so learned, they need to learn it all over again.
Change through selective breeding within a species, as documented here, cannot, of itself, produce a new species, for the patently obvious reason that species are reproductive 'islands unto themselves'. In other words (as Adam understood) dogs will always be dogs and woodpeckers will always be woodpeckers. If a terrier has a cecal valve, and a poodle doesn't, does that have anything whatsoever to do with whether or not they can breed and produce viable pups? If a woodpecker had a cecal valve and a poodle had a cecal valve, but a terrier didn't, would a woodpecker and a poodle be any more likely to produce pups (fledgelings)? Species are defined, wherever possible, on the basis of reproduction. That's why they have cages, and signs on the cages, at zoos. There are species. The reason the species are species is because there is a mechanism built into them that keeps them 'locked' - as unique, reproductively self-contained units. (This is not to deny that difficulties arise in precisely categorizing certain groups of living things. And, yes, the 'lock' must be 'trippable' to have allowed species transformations.)
Just this month, a paper came out - from the Uni. of Texas I think it was - explaining one theory as to how this locking might happen. This paper was linked to by PvM in the head of a page titled, IS IT ALWAYS APRILS FOOLS DAY AT UCD - see PANDA'S THUMB, this month, earlier on.
PZ, WHEN ARE YOU GOING TO CEASE THIS UNPROFESSIONAL MISLEADING OF PEOPLE IN THE NAME OF SCIENCE, AND FRONT UP FOR PEER REVIEW? Bring the whole team, lock, stock, and barrel. I'm still waiting.
Cards on table first: A level Biology (25 years ago), and a continuing interest in natural/environmental sciences, fostered by my parents. Plus, Christian (in the practicing/believing/committed sense). Plus, English.
Comments:
Looks like I need to add another blog to my daily reading list:(
PeterP, welcome! I'm newish here, but I'll try not to misrepresent the community too badly.
It's the nature of this blog, more than anything else. PZ is a biology professor who posts about a variety of things, but most often about misrepresentations of science and the antics of anti-science clowns like the Discovery Institute and the bunch that made Expelled (*jazz hands*).
There are many intelligent and accommodating readers here (and there's me, too!), and there are equally intelligent readers who enjoy brawling with the trolls that turn up regularly. It's the internet, you may be familiar with its tender sensibilities and 'G' rating. As a rule of thumb, religious visitors experience rudeness in proportion with how literally they interpret the bible. If you're from England you should be fine ;)
Goalposts. To adopt the metaphor, proper science should concede the goal, take down the goal posts, erect them somewhere more sensible and try again. The complaint against ID is that they won't decide where to put the goal posts in the first place. Specifically, you will often hear "Intelligent Design makes no testable predictions".
Anyhow, welcome again. I hope you enjoy your stay.
Silly me...and here I thought they had signs so you'd learn about what you were looking at, and cages so that no one gets mauled.
I guess that means if the bears weren't in a locked enclosure, they'd be out reproducing with humans all day long, the little sluts.
Thanks for clearing that up, Mr. Jablomey.
If all creatures descended from common ancestor(s) without a species lock, as Common Descent Evolution seems to say -- precisely. Live in cages, to stop reproduction with bears.
Sir R. Menzies, late Prime Minister of Australia, was once baited by a large, boorish male. "Now tell us the story of Goldilocks and the three bears!" he shouted. Menzies looked at him quizzically, and said, "I can see one bear, but where are the other two?"
Silly me...and here I thought they had signs so you'd learn about what you were looking at, and cages so that no one gets mauled.
First Old Woman:
Oh, I wouldn't like that, it would take the mystery out of life. Anyway if it was from the zoo it would have 'Property of the Zoo' stamped on it!
Second Old Woman:
No it wouldn't, They don't stamp animals 'Property of the Zoo'!!! You couldn't stamp a huge lion.
First Old Woman:
They stamp them when they're small.
Second Old Woman:
What happens when they moult?
First Old Woman:
Lions don't moult!
Second Old Woman:
No, but penguins do. There, I've run rings around you logically.
First Old Woman:
OH, INTERCOURSE THE PENGUIN!!
Phillip is off his meds again I see.
Ah, the other two showed up.
I know that's the only thing that stops *me* from doing it (insert old Alaska joke here).
As always, Ichthyic, we can count on you for le mot juste.
I think this thread is now pretty much intercoursed as well.
OH, INTERCOURSE THE PENGUIN!!
NO PENGUIN LUST!!
*BOOM!*
how literally they interpret the bible
I guess I need to find another blog to debate that claim with them, and keep my science questions on this one!
So, here's something I thought of after yesterday's note. How are 'species' (kinds?) defined now? When I did my biology, it was to do with reproduction (giving fertile offspring). Now I understand it's more to do with DNA sequencing. Has anything been done to determine whether these new lizards are a different species? The latin names used suggest they're considered a sub-species (but perhaps the use of 'third names' has changed?).
Micro vs macro evolution: I thought this used to be a debate that said something like 'we accept that generations change within a species, but can't see how a new species arises' ("which comes first, the chicken or the egg?" stuff). If the definition of species has changed (or disappeared altogether), what do people now mean by this discussion?
Any help appreciated! Less scientifically educated (yep, even less than me) Christians ask my views, so it's good to keep up to date.
I would assume that they are still the same species and still able to interbreed as 30 years is too short a time for speciation. Polar bears and brown bears are still able to interbreed under artificial conditions in zoos to produce fertile offspring and they started to diverge 200,000 years ago. Ring species such as the herring gull complex might also be relevant.
Peter
This is a good place to start
http://evolution.berkeley.edu/evosite/evohome.html
check out Evolution 101
"Believing in microevolution but not macroevolution is like believing in inches, but not miles..."
I want that on a magnet, since I have no car. [T-shirt would be nice, too.]
Seriously though, my explanation for being able to believe in microevolution versus macroevolution is:
Brain size.
Tiny minds can't think on a bigger scale. They're not adapted to think larger - they have to think SMALLER.
Hence, microevolution is accepted; macroevolution is not.
Too big a concept to wrap a tiny mind about.
RE: Barnacle penises.
I did not know that.
[Coming up: barnacle porn?]
Some more musings on these lizards and their nematodes.
Thank you thalarctus for your offer to contact the corresponding author of the paper. Mollie kindly sent me a PDF of the article so I do have that access information if necessary ... but I really am supposed to be hanging drywall today instead of researching lizard gut nematodes. I knew nothing about cellulose digesting nematodes before this and have enjoyed the learning experience of reading here and elsewhere.
Some points from the paper that may not have been expressed here;
The present introduced population of lizards, Podarcis sicula Mrcaru have a larger overall body size (not just a more robust and differently proportioned skull) than the population on Pod Kopiste from which they originated.
Female lizards (which normally have a smaller narrower head) showed the greatest divergence in head proportions, indicating that selective pressure was for greater biting ability.
A hatchling P sicula Mrcaru with umbilical scar, had the cecal valve.
On the question of the origin of the endosymbiotic nematodes in the introduced population;
Although another Lacertid species, Lacerta oxycephala, is found on some Adriatic islands, the text of the paper seemed to indicate that the extirpated P melisellensis was the only other lizard population upon Pod Mrcaru.
This is within the range of Hermanns Tortoise but I guesstimate that their presence is unlikely on this small island.
Cellulase production is common in plant parasitic nematodes.
Of the article abstracts (I'm on the wrong side of the "full article" firewall) I found, these two seemed most relevant;
Evolutionary Genetics of Insular Adriatic Lizards
http://www.jstor.org/pss/2407141
The Adriatic contains over a thousand islands. Many have lizard populations, and the pattern on the smaller islands is to have either P sicula or P melisellensis. Rarely do the two exist in sympatry on small islands.
Correlating diet and digestive tract specialization: Examples from the lizard family Liolaemidae
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B7GJ0-4GV9SBH-…
Examining South American Ground Lizards, the authors found;
A larger overall body size in herbivorous lizard species.
A proportionally larger small intestine in herbivorous lizards.
"Of the species with nematodes, over 95% of herbivores had nematodes only in the hindgut. Prevalence of nematodes in the hindgut of herbivores was 2× that of omnivores and 4× that of insectivores." So the authors found hindgut nematodes in 24% of the insectivorous lizards examined. It is not out of the question that the original insectivorous P melisellensis Mrcaru population harbored nematode endosymbiotes.
On further reflection, it might be hasty of me to use the term "endosymbiote" for gut dwelling nematodes within an insectivore. Commensal, non-mutualistic gut nematodes earning a living stealing hard earned nutrients from a bug-eating reptile, could well retain the genes for cellulase production, which would be very useful if the worms took up residency in someone with more herbivorous habits.
Peter P.. Careful about asking intelligent questions around here. You might be branded a madman, or be trampled by bears. The real world is foreign to hard line Darwinian thinking. Been there myelf to some extent, and can partly understand how the unreality gets a hold.
The species definition always has been and is, now, ideally, reproductive self-containment. Get's a bit obscure with some plants, many micro-organisms, and, of necessity, with some extinct organisms, such as, say, brachiopods that display wide variety of shell shape. Reproductive self-containment is the foundation of taxonomy and the goal of the classifier. I was taught that by a leading palaentologist and a Darwinist to boot. Yes, and ARCHAEOPTERYX fits within this definition, perfectly.
Be not smoke-screened by this talk of hybridization and such like. Hybridization is only detectable because there are definitive species. Such phenomena presumably tell us that all species arrived here through a process, and the possibility of hybridization is reflective of or indicative of this process (attempted return to unity with the common CONDUIT species that pre-dated the hybridizer(s)).
Microevolution has this much to do with macroevolution, and probably no more: responses of a species to its environment conceivably might have been programmed in to a species' information bank, and when the moment for transformation arrived, that information became a factor in the form the new species took. The technology is there, to do it: we just have barely scratched the edge of that technology.
Darwin was 150 yrs ago, after all; and his followers seem to have gotten stuck, well back before his times!
I'm sure you can.
Philip Bruce Heywood, I'm not sure what position you're arguing there. In what way do you think hybridisation is confusing, and how does archeaopteryx come in to that? What's all this about conduit species? you make it sound like a derived form is some kind of aberration that wants to return to the original 'kind'.
Are you arguing that species have a certain amount of variability built in, and subspecies are just an expression of that? That's an extremely fringe view, and I'd like to see some science to back it up.
Let's see... "Careful about asking intelligent questions", Darwinist, our LORD of the CAPSLOCK, "definitive species", "conduit species" (?!?). Sounds like a creationist on the troll to me. Oh, I should have just looked at the link in your name: www.creationtheory.com/
I'd be happy to feed your persecution complex if you like, or if you prefer you could show some evidence for your bold statements.
P.S., don't look up the ring species Wayne Robinson mentioned, your head might explode.
Correction to my previous entry: not all Darwinists are stuck, back in the past. Darwin did have something to contribute. His true followers will be up front with the latest technologic developments, keeping his idea rolling. If that means abandoning some of his concepts, so be it.
Hematite: I hope, contrary to your label, you aren't rusty. I'm sure you're not.
Darwin, Wallace, Huxley & co., tried to account for the observable species. They rejected - perhaps not without some reason - the advice of their superiors, such as Cuvier and Richard Owen. They and their followers never 'cleared' their ideas by consulting with cold, hard, physics, developed by people such as Joule, Kelvin, and Faraday. Those who have attempted to follow their reasoning have become so lost, they no longer have a clear concept of the very Species that Darwin and co. hypothesized about. Evidence? Look at PANDA'S THUMB. Ring species, no species, bridges such as ARCHAEOPTERYX that suddenly aren't species, speciation through hybridization, species arriving all the time, every time someone goes to hospital and has a baby. Just add a few years and some jargon - hey presto! It's all here - just read.
Are you ready, Mr. Iron Man, to sit down here and now, admit the facts of nature that Darwin & crew were so hasty to explain without the benefit of microbiology and modern physics, and explain those patently obvious facts of nature without recourse to anything except hard, known fact, plus logic? Join PZ & co., and roll up and explain what all this fandangled brass band is about. But don't try pulling the wool. If, for example, contrary to Darwin & co., you won't accept that there are clear-cut species, we are wasting our time.
Philip Bruce Heywood:
What do you suggest these are evidence of?
I fear I must disappoint you. I am well aware of the difficulties in defining species boundaries, despite the fact that I can tell the difference between a cat and a dog. The fact that 'species' are labels of convenience is quite important to the understanding of modern biology, and how populations can change over generations.
I'm sure you have a theory of how to define species and how they arise; I am curious to hear it. Although if it is the same one on creationtheory.com, I have yet to be impressed.
I'm going to try to only click once this time. Well, Mr. Hematite, you are honest in that you clearly state your position. If everyone else would just do the same, and openly advertize, say, that "My science owns that EOHIPPUS gave birth to OROHIPPUS (or whatever the next in sequence was),a clearly genetically distinct species, and did so in the same way as mum going to the hospital and having a baby - why, students and the public could decide whether they needed to listen, or not. Even that much honesty, on the part of all players, would go miles in defusing the evolution controversy, and in giving policymakers a clear understanding of what they are actually dealing with, when presented with data that just might have an idealogical as distinct from empirical input. My compliments.
Ah, species are defined (if you like) in a CHEMICAL sense. It's all to do with proteins and sex cells and cell walls and that microbiological stuff. Everyday observation concurs with the 'chemistry'. I don't define species at my site - the public has been defining them since Adam, and the technology is now showing that everyday observations do count for something. The same technology is now showing that the difference between species is empirical: i.e., it can be measured in terms of chemistry; and the pathway of transformation from one species to another can be quantified in terms of hard, if post-classical, physics. Enter the cutting edge technologies. This debate is finis, dead, gone, done. Try reading SCIENCEDAILY, daily. Sorry about the anticlimax.
Just a warning to people who have not come across Philip Bruce Heywood before. He is quite capable of attributing things to you that you have not written, attacking you on that basis and refusing to retract.
PBH: Are you ready yet to apologise to J. Biggs or myself yet?
Eh, Simonsy, how're you progressing, scratching that leaf leaf leaf leaf? I've got another one for you. Stand up, rub stomach in clockwise direction, rub top of head in anticlockwise direction. Not so easy to go countercyclical, eh? Very well, simply move hand up and down on top of head, with some force. Now place one ovum freshly laid by (female) member of GALLUS GALLUS, on head. Proceed as before, and recite Shakespeare: "Pray thee, sweet Mistress Margaret, deserve well at my hands by helping me to the speech of Beatrice.
Marg. Will you then write me a sonnet in praise of my beauty?
Benedick. In so high a style, Margaret, that no man living shall come over it; for, in most comely truth, thou deservest it.
Marg. To have no man come over me? Why, shall I always keep below stairs?
Benedick. Thy wit is as quick as the greyhound's mouth; it catches.
Marg. And yours as blunt as the fencer's foils, which hit, but hurt not.
Friends, Romans, Countrymen, this brave new world, that hath such creatures in it, ETC...
This reminds me of the red indian - a dinkum red indian, to be greeted with, How! - who had a prodigious memory. Someone went to some trouble to interview this 'injun, to test his supposed perfect memory. By way of introduction, the interviewer asked the aborigine what he liked for breakfast. The subject intimated that he liked the ovum of GALLUS GALLUS. This so impressed the interviewer, he sought no more evidence. Encountering the indian some 20 yrs later, however, he greeted him with, How! and was advized, "scrambled".
What natural selective value there is in domestic fowl having such large ova, I often wonder.
From the looks of that last post, it seems like PBH is either off his meds or on some illegal ones.
Phil:
Learn to drive the Google. You can learn stuff.
Stuff like this.
Fascinating post. Certainly beats reading about that stupid so-called 'documentary'.
Berowne: This jest is dry to me, Fair gentle sweet.
The Princess of France: Here comes Boyet, and mirth is in his face.
Boyet: O, I am stabbed with laughter!
Hmm. Shame Phil's brain seems to have melted. Well, I shall quit the discussion, match cancelled due to the poor weather in Phil's head.
Maybe he should see a meteorologist.
What an opportunity for the ID crowd! Now they have a potential test of their ideas. Unless they wish to admit that standard biologial procedures can produce such changes they should try to show that the new structues are designed, and designed so recently that the great Designer must be alve and will, dwelling somewhere. It should be possible to trace the design intervention and backtrack things to the source. Soon out beloved IDers will be able to give out web addresses and home pages of the Designer himself. After all, if there is an intelligent designer, such a designer should have no trouble designing a wb page--that is so much easier that a bacteria flagellum.
Just for clarification's sake, here's the difference between macro and micro evolution.
Micro - physical changes that come to a certain species through the environment. This allows creatures to learn to live in different places, but doesn't change one species to another. It's about equal to a person living in cold weather all the time and never needing a coat, whereas a person from a warm climate would be bundled up there.
Macro - genetic changes that occur through gene mutation by random genetic "mistakes" during egg development once it has been fertilized. These random mutations may be caused by accident or environment, and are what theoretically allow a species to change to another.
I personally don't buy this. It seems like they're just making a big deal out of some adapted lizards. After all, an organ CAN develop where the species didn't have one before, all without changing the species.
Take humans, for example. It is not considered typically human to have six fingers. However, there are recessive genes that cause some people to have an additional finger or two. Also, some humans can be born without certain organs.
Trick is, any species that is inbred, as is the case of the ten lizards, recessive genes will come out. Possibly those jaws and muscles are recessive genes, and now that most of that particular sort of lizard is away from that particular gene pool, there is a greater chance of different genetic expression that is more unique to that gene pool.
Them's some mighty big words you're using there, son.
Too bad you don't understand what they mean, That's what happens, though, when--instead of learning--you just pull stuff out of your cloaca and string it together.
I personally don't buy this.
good that you don't buy your own strawmen.
we don't either.
just to make it clear for your tiny brain, using your own personal definitions of words and then saying "you don't buy it" marks you as, um, insane.
Trick is, any species that is inbred, as is the case of the ten lizards, recessive genes will come out.
if you had even begun to try and utilize your tiny brain, you might have paused to consider that these traits did not exist AT ALL in any of the parent populations of these lizards, which they would have if they were based on recessive genes.
now then, until you can stop making up shit, I suggest you try and find another sandbox, cause strawmen don't stand up well around these parts.
The islands Pod Kopiste and Pod MrCaru are near each other. Isn't it possible that a hundred generations earlier, the Podarcis sicula moved to the island themselves? We know iguanas can find themselves hundreds of miles away just by floating on rafts. Reptiles, being cold blooded, can go long periods of time with little or no food. Therefore, it is logical to suggest that Podarcis sicula had already arrived on Pod MrCaru before 1971 by floating on logs or something. This would lead the researchers to believe that the overwhelming population of Podarcis sicula in 2004 was descended from the ten individuals they had place there because they would show similar genes. We should consider the possibility that the Podarcis sicula were already there and that this huge leap took place in something closer to one hundred generations or more.
Also, reptiles lay plenty of eggs, but consider: they had ten different genotypes. That is not a lot of variation. There would have to have been a lot of inbreeding which would certainly not lead to beneficial mutations.
In conclusion, it is undeniable that this newer Podarcis sicula evolved from the older Podarcis sicula. My problem is: how can we be sure that these are the descendants of the original ten and not from a larger group that landed on the island generations prior?
Great example, but I have couple of questions. Did the transplanted P. sicula evolve a cecal valve as the of a mutation that caused a dormant gene(s) to be expressed? Was the gene associated with the cecal valve entirely absent from the original P. sicula's genome?
Oops, my post should have read as follows:
Great example, but I have couple of questions. Did the transplanted P. sicula evolve a cecal valve as the result of a mutation that caused a dormant gene(s) to be expressed? Was the gene associated with the cecal valve entirely absent from the original P. sicula's genome?
Great article and interesting example.
However, I don't think that many creationists will find it convincing because they are still lizards. Most will want to see lizards become hamsters or something before they find the evidence convincing.
Perhaps Ray Comfort needs to see the lizards become bananas or coke cans before this example becomes relevant for him.
On an interesting side note, I'd love to see a cool .gif where Kirk Cameron & Ray Comfort whack eachother in the nuts with bananas and coke cans. Can anyone make one for our general use?
This is micro-evolution, but that is all that can happen, this lizard always had the genetic information to produce the cecal valves, and grow different skeletal traits, like people, there is variability depending on environmental factors. This is just a perfect example of genetic adaptation, but not evolution, the species could just as easily change back.
How do you know that? Or is it Creationism to talk out of your arse?
Lets, see, old thread, no evidence, just opinion produced. Lots of talk on micro/macro evolution, but no talk of how the genome actually works, duplicates itself, how genes double in number, undergo other modifications and fissions back together. Must be an ignorant Creobot.
Saying this lizard evolved at all is not correct, like the spotted moth, it is just a recessive gene trait that proved dominant in the lizard after environmental changes, that would be like saying that there are different species of Homo Sapien Sapien because of different facial bone structure, size, skin color, etc. The gene traits that caused the changes already existed in the lizard. That is not evolution, it is a brilliant example of the flexibility and survivability of the animal.
Joe, please cite the scientific paper backing your supposition.
Care to provide some actual science to back that up?
It's amazing what you can assert with absolutely zero evidence when you have God on your side.
it is just a recessive gene trait that proved dominant in the lizard after environmental changes, that would be like saying that there are different species of Homo Sapien Sapien - Joe
Joe's playing "how many stupid errors can I get into one sentence". Joe, "dominant" and "recessive" are terms for alleles of a gene, not for traits (which are phenotypic attributes); and it's Homo sapiens sapiens - depending on how you count them, that's up to 8 errors in three words! Bottom of the class, Joe, must try harder.
joe kind of reminds me of AFDave.
So I point out a probable flaw in this study case, and you automatically assume I don't believe in Evolution, and then pick on my grammar? Get an argument. plz.
That's a pretty bold use of the word "probable".
If it is probable, back it up.
Plus Nick wasn't just being critical of your grammar, he was pointing out you aren't even using the terms correctly.
Thats my auto-correction at its best... As for backing my probable claim up, there is not nearly enough information on this topic to make or break any scientific conclusion. The population was not monitored, for example, for all we know the lizards evolved to birds, brought new lizards that kinda looked like themselves back for decoys and then went on vacation... how is that for probable?
Joe, if there is a flaw with the study, the proper thing to do is to write a paper to a scientific journal pointing out the evidence for the flaw. Have you done so yet?
As yet you haven't shown any evidence for your presumption. Drawing doubt is not evidence, and won't be until it hits the scientific literature.
Yet you chose to use the term probable. Probable implies that there is enough evidence to make the claim that this is the most likely explanation. Something which is far from the truth.
Shitty.
that should have read
KoT
"the little islands were completely neglected for 36 years" this statement alone puts a damper on my enthusiasm for this... that's all I am saying, stop torching people who dont agree with you.
Joe, you haven't been torched, you have been refuted. Soundly. We have been polite to you personally, but not your ideas. Big difference.
I just do not see how a claim like this can be made without being monitored for the whole 36 years. plz explain.
Joe, read the paper. Then study science and how it works. There is no problem with the paper as the paper is scientific. Now, you have to prove it wrong with evidence to the contrary. No questions, no doubts, but hard evidence. Be sure to show your work. And when done, write it up for publication in the appropriate scientific journal.
That's fine but you immediately jumped to the conclusion you claimed was "probable" with nothing to support it.
Before I comment, I'd like to point out that I'm a naturalist that believes whole heartedly in the near fact of evolution and common descent.
The question regarding latent genes being the possible source of the cecal valve appearance in so few generations has arisen a few times. PZ wrote: "The cecal valves are an evolutionary novelty, a brand new feature not present in the ancestral population and newly evolved in these lizards." PZ, you should feel honored, you were cited in wikipedia as the source of the same claim (which lead me to this article). PZ later reiterates his claim by stating: "There are herbivorous lacertid, agamid, and iguanid lizards that have cecal valves." This statement is drawn directly from the paper in PNAS.
My point is that P. sicula is a genus of the lacertidae family. Does it not appear that the evidence is pointing toward the idea that cecal valves very well might be a result of the reemergence of unexpressed genes? I'm not a biologist, and I haven't studied the evolution of this particular lizard. That being said, I assume P. sicula being a subset of the lacertidae family means they share a common ancestor with other lizards that have exhibited the same trait (however rare it is ... 〈 1%). Given the small number of generations in which the trait appeared, intuitively it seems that the activation of a gene or set of genes that already existed in some form is most likely. As PZ stated, more experimentation is necessary, but if I were a betting man my money would be on the idea that this is not the evolution of a new morphological trait. Please correct me if I'm wrong; is the statement: "a brand new feature not present in the ancestral population and newly evolved" possibly a mistake?
JTG, evolution is change with time. The lizards evolved based on needing to eat more plant material. I suspect, like you, that the change was due to activating old regulatory genes since very little time had passed. As far as the ancestral population statement goes, it depends on the ancestral population that is being compared to. In this case, the paper and PZ appear to be comparing the present population to the originally transplanted population. In which case the statement is correct. Going back million years or so, it probably isn't correct.
Lrg prdcts whlsl sl, prvds cstmrs dmnd