…and this is a 
How do we explain the diversity of species in the world? The core process is speciation, a splitting of a lineage into two divergent lines that at the end, cannot interbreed. What do we know about speciation in Darwin's finches?
They evolved from a common ancestor in 2-3 million years into 14 different species, filling different ecological niches in the Galapagos, largely free of human interference. Showed us photos of four different species with very different beaks.
Developed predictions of population density from things like available biomass, and worked out relationship of expected density to beak size. It seems to have worked, with good correlations between where the environment provides the best opportunities and the kinds of species that are actually present.
Different birds in different environments have different characters, presumably generated by adaptive processes. They frequently observe matches between species present and available food supplies. This is a historical interpretation: what is needed is direct observation of morphological changes in response to changes in the environment.
How much genetic variation is extant in a population? They assessed this in bird populations on Daphne Major, measuring heritability of beak size (value = 0.74, about the same as heritability of height in human populations).
How much genetic difference is present between species? Two genes show consistent graded pattern that correlate with beak shape: BMP4 and calmodulin. Inserting finch BMP4 genes in chickens produces chickens with larger beaks. Most of the variation is thought to be not in structure of genes, but in their regulation.
Describe size-dependent mortality in birds during drought — large birds survived better. Used r=h2s to predict what the average beak size in subsequent generation, tested it, and found a very good fit.
Later rainy year led to a second evolutionary shift, back to favoring smaller birds. They now have a body of data describing almost 30 years of evolutionary responses to 5 drought years. Mean trait values are changing over these years. The birds are not the same morphologically now as they were at the start of their study. Have seen an identical drought condition in 2005 to drought in 1983, but in this recent drought, saw a different reaction. Now, there is a substantial population of magnirostris on the island, so the response to drought is decline in beak size: they are seeing character displacement to increase differences between two species.
Rosemary Grant took the lectern to talk about courtship. Finches can recognize conspecifics by both morphology and song. THere are individual differences, but also larger species differences. Song is learned early by young birds, mainly from the father, and once learned, it is retained for life. Song is learned in a Lorenzian fashion by imprinting, forming a pre-mating species barrier. Sometimes, males will take over a nest of another species and fail to toss out all the chicks, so you sometimes (1%) get individuals that learn a foster-father's song, of a different species...so you get hybrids later in life.
Hybrids were not seen to survive any of the drought years. Hybrids had intermediate sized beaks that did not thrive when only large, tough seeds were present, but could do well in wet years with abundant small seeds. In those cases, hybrids survived as well as parental types, so their death is not a result of genetic incompatibility.
These hybrids trickle cross-species genes into the foster parents' species. Will this lead to fusion of the two species? Maybe not, because drought reinforces differences.
Also, some hybrids with magnirostris seen — they don't breed back into the population. They can't compete with the purebred magnirostris, and the purebreds also beat up the hybrids.
Life Science
Comments
Posted by: Autumn
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October 30, 2009 12:14 PM
I read The Beak of the Finch a while ago, and I love that it gives nice hard data supporting the predictive power of modern evoloutionary theory. It's one of the things I like to mention every time I hear some wingnut ranting about evoloution making no predictions. There's a lot of others, of course, but a nice book written for the public is more accessible to most people than journal articles.
Posted by: Eidolon | October 30, 2009 12:24 PM
While fighting off godbots and woo are great fun, this and the previous two posts are what really make this a special site. That, and the angst from the creotards. And the bacon.
Posted by: Sven DIMilo | October 30, 2009 12:31 PM
This is the good stuff. A 30+-year field study!!! Envious, am I.
Posted by: Glen Davidson
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October 30, 2009 12:35 PM
Oh come on, isn't persecuting Xians part of the fun? Expelling them, censoring them, you know, all of the tremendous suppression of their soon-to-be triumphant ideas (I never quite figured out how they're both about destroy evolution while we never let them have free speech, but it must be so).
I have a cord of IDists I intend to burn this winter.
Glen D
http://tinyurl.com/mxaa3p
Posted by: lose_the_woo
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October 30, 2009 12:44 PM
Why don't you give it a rest already PZ. More woo-bashing please. This is a science site isn't it?
/snark
Great stuff PZ. Thank you.
Posted by: David Marjanović, OM | October 30, 2009 12:47 PM
Too cool.
That's one of the 147 species concepts.
And under that particular concept (as well as the closely related one under which two species won't interbreed in the wild even though they can under lab conditions), there is only one species of ground finch in the Galápagos, not three, because the mentioned hybrids are perfectly fertile.
Global warming is messing with El Niño and La Niña, though. If the drought gets switched off, species fusion will happen.
(Except, again, under the two so-called Biological Species Concepts, under which there's only one species there to begin with.)
Posted by: lose_the_woo
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October 30, 2009 12:54 PM
With this large body of knowledge regarding Galapagos finches and the level of detail, has any
apologistcreotard even attempted to reconcile it with their fable?Certainly there are more than a few claims here that they could conceivable "destroy" with their book of answers. Right?
Posted by: Matt Penfold | October 30, 2009 1:04 PM
I suspect they just fall back on claiming it is only "micro-evolution" and that the finches are still finches and have not turned into budgerigars. The usual crap.
Posted by: ceu | October 30, 2009 1:10 PM
I am very fond of mules. The sterile missing-link between horses and donkeys. They tend to be creatures people have contact with, therefore, it isn't a theoretical concept of an extinct or distant life form. They meet, or hear, mules at some time or other. And the existence of a sterile cross breed does beg the question "why?".
Can zebras interbreed with horses or donkeys? I haven't met anyone who knows (If Dawkins mentions it in Greatest Show I'll find out soon enough.)
I'm also very fond of the cabbage family: broccoli, turnips, kale, brussels sprouts, etc. These veggies all still interbreed, hence the growing diversity within the family as new forms arise from cross pollination. Many people garden, but not all of them save seed. Enough do to generate conversations about evolving plant lines, especially when contrasted with the onion plants - leeks, scallions, onions - that no longer cross pollinate.
Anyone inspired to create a line of childrens' books on this theme? I'm not a writer, but maybe one of you...?
Posted by: skylyre
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October 30, 2009 1:21 PM
Hi ceu,
Have you ever heard of a That's the wiki article about zebras that are bred with horses, donkeys, mules... bred by people of course, they won't in nature.
Posted by: skylyre
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October 30, 2009 1:24 PM
oops :) i suck
Posted by: lose_the_woo
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October 30, 2009 1:27 PM
Of course, "micro-evolution". The compelling notion that small changes can occur over small periods of time, but small changes occurring over large periods of time never lead to large changes. Makes perfect sense.
Unfortunately though, I think you're spot-on with that assessment.
Posted by: kopd | October 30, 2009 1:37 PM
I hate the micro-evolution argument. It's like saying sure a child can age but they can never get old. So stupid!
Posted by: kopd | October 30, 2009 1:43 PM
hybrid /= missing link
Posted by: Rev. BigDumbChimp | October 30, 2009 1:46 PM
Missing link?
Posted by: lose_the_woo
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October 30, 2009 1:50 PM
fond
adj. fond·er, fond·est
1. Having a strong liking, inclination, or affection: fond of ballet; fond of my nieces and nephews.
2. Affectionate; tender: a fond embrace.
3. Immoderately affectionate or indulgent; doting: fond grandparents who tended to spoil the child.
4. Cherished; dear: my fondest hopes.
I'd be careful when using "fond" as a word choice - especially when referring to donkeys. That being said, beast love isn't considered taboo everywhere - so I've heard.
Posted by: Ring Tailed Lemurian | October 30, 2009 1:51 PM
#9,10,11
Mules aren't always sterile. There are documented cases of female mules giving birth.
http://www.denverpost.com/haley/ci_6464853.html
excerpt-
Posted by: Sven DiMilo | October 30, 2009 2:06 PM
"Winston"Charlie, your personal incredulity is still not a persuasive argument to anybody else. When will you grok this?Posted by: Ring Tailed Lemurian | October 30, 2009 2:21 PM
Winston Wolfe #18 & 20
It's obviously too much to expect you to think before posting, but could you please use the "Preview" before posting?
Posted by: Winston Wolfe | October 30, 2009 2:22 PM
"When will you grok this?"
Sorry Sven, I will never grok neo-darwinism.
I do, however, grok Spock!
Posted by: kopd | October 30, 2009 2:26 PM
You seem to be forgetting that evolution works on populations, not individuals. Sure, faster antelope will occasionally stumble and become dinner. But as a population, the antelopes that are better at getting away from the lion will be dinner less frequently.
And this:
"The ones with a slight advantage live longer and are more
likely to pass the advantage on." This is the assumption that underpins most of evolutionary theory.
is poorly worded. The ones with advantages that can be passed on are more likely to out-compete those that don't. And it's much more than an assumption. It's an observation. I'll let smarter people than me address the rest, if they feel inclined.
Posted by: Rev. BigDumbChimp | October 30, 2009 2:28 PM
Your opinion has been and still is a steaming pile when compared to the actual science.
Which of your previous sessions of argument from personal incredulity did you copy and paste that whole response?
Because it is a copy paste job. Maybe your own words, but still copy and pasted.
Show us your MENSA card again too please.
Posted by: lose_the_woo
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October 30, 2009 2:30 PM
I think he was referring to you sounding like a pretentious ass does nothing to sway anyone here of your imagined authority - or your comprehension skills. Grokky?
Posted by: Eidolon | October 30, 2009 2:32 PM
Glen @4:
We can never know how they can be triumphant and persecuted so harshly at the same time. Gawd works in strange (and psychotic) ways.
As for the burning, just make sure that there is not a 'no burning' advisory in effect, since they do tend to smoke a bit.
Posted by: CJO | October 30, 2009 2:34 PM
This idea that organisms with beneficial mutations will invariably be better off than those with less favorable adaptations and that natural selection will cull out the bad and save the good, is not an overriding tendency.
That it's not invariable doesn't mean that it's not an overriding tendency. It overrides all of the contingent events, resulting in a statistical tendency for the fitter variants to out-reproduce their conspecifics. The "fittest" antelope ever born could have been killed an hour after birth by some mischance. It doesn't matter that the fittest don't always survive; it matters that the fittest tend to survive more that the less fit. And, yes, the edge there can be very small indeed. But you're pitting you limited intuition, which is calibrated to the spatial and temporal scales of a human lifetime, against a massively parallel process acting on vast numbers of phenotypes over vast periods of time.
Dawkins has a discussion in one of his books about wasp orchids, flowers that mimic the appearance of the female of a species of wasps and are fertilized by males attemting to copulate with them. He poses the question: could it really matter to a male wasp that a given flower looked 1% more like a female wasp, a necessary condition for the adaptation to have evolved through small, successive steps. Our intuition says no, but we're not taking into account hundreds of thousands of flowers and hundreds of thousands of wasps, every year, for hundreds of thousands of years. Plug in those kinds of numbers and the slight, 1 percent improvements can actually be significant.
Posted by: Ring Tailed Lemurian | October 30, 2009 2:41 PM
Winston Wolfe #26
Take a look at your posts. As Rev.BDC says, you're cutting and pasting. Whatever you cut from (a preious post? Notebook?) has end of line makers, which get transferred.
If you can't be bothered to make it easier for your readers, why should they bother to try and read it?
Posted by: Ring Tailed Lemurian | October 30, 2009 2:48 PM
Heh, me #30
Skitt's Law.
Posted by: MrFire
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October 30, 2009 2:50 PM
?
Wait - are you saying this is evolution, or not?
Except for all those books and papers that do just that?
What?
In the end, it's just a glorified cis-trans double bond switch. But then I'm a chemist and hate all that icky bio stuff.
Entitled to your opinions, you most certainly are.
Posted by: kopd | October 30, 2009 2:54 PM
It gets tiresome repeating the same thing over and over.
It gets tiresome on this end to. There's a reason it's called argumentum ad nauseam.
Posted by: Rev. BigDumbChimp | October 30, 2009 2:56 PM
OK, cough up the MENSA card jpg
Posted by: Eamon Knight
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October 30, 2009 4:34 PM
Sounds like the same/similar talk that they gave here back in April. Unfortunately, one of our local creationist clowns showed up to display his stupidity (same as he did for Dennett's talk back in February). However, I suppose both Dennett and the Grants are used to it.
Posted by: Sven DiMilo | October 30, 2009 11:40 PM
tee-hee!
Posted by: David Marjanović, OM | October 31, 2009 10:39 AM
You don't have the right to make up your own definition of evolution and to then claim the one everyone else uses is wrong.
Evolution = descent with heritable modification. That's all there is to it.
It's not. It goes wherever the climate leads.
When the climate oscillates, it will oscillate. When the climate is chaotic, it will be chaotic. When the climate is stable, it will be stable.
If El Niño stops, in other words if droughts in the Galápagos will stop, so will all "oscillations", and the three species of ground finches will merge, because the only factor that keeps them apart is natural selection by drought.
This is not an assumption, moron. The Grants measured it! That's the whole fucking point of their research!!!
How stupid did you believe we are?
Antelopes don't need to outrun the lion. They only need to outrun each other. Here's why:
Not that much.
Cheetahs get the entire herd running to see which antelope is the worst at running, and that one gets targeted.
Lions are ambush predators. They don't select for running speed as much as for the senses. By the time the antelope starts running, it's dead meat.
This happens often enough to provide natural selection against stumbling: better senses, more robust joints, quicker reactions.
And you exaggerate it.
I repeat myself: it's not an assumption, the Grants have measured it. What exactly did you think they've been doing on that lonely rock for the last thirty years?
Not "might". The Grants have measured it.
Yes, of course.
Evolution does not mean "progress". It means "descent with heritable modification".
Natural selection can change course; it does so whenever the environment changes. This means that sometimes it turns around by 180°.
"Simple"?
How the fuck could a gene frequency oscillate?
If there's no selection, we'd expect random drift (and indeed we've observed it in a few cases), eventually leading to fixation when the frequency of one allele happens to reach 100 % (also observed). But an oscillation? A regular cycle? How would that work?
Natural selection can do it. Suggest something else. Go ahead! We're waiting.
Yes, exactly. When conditions changed back, the direction of natural selection changed back, so suddenly the lighter moths got their former advantage over the darker moths back.
This doesn't somehow happen on its own.
Gene duplication followed by mutation...
Really, stop forming opinions based on your lack of knowledge. Go read. There's a lot of knowledge out there that you don't even imagine exists.
Wrong universe.
Bingo. Evolution is a statistical process – the change of allele frequencies in a population.
Posted by: David Marjanović, OM | October 31, 2009 10:43 AM
Sorry, forgot the Comic Sans tags at the last moment.
Posted by: SEO UK | November 16, 2009 9:25 AM
Everyone forgets, it's a bit different to judge or comment upon evolution from within it.
BB