Rapid Reptile Evolution

Scientists release seemingly harmless Italian Wall Lizards on a deserted South Adriatic island in 1971... and return to find walking, talking, boccie playing super-lizards! That is the headline that would have been written if researchers from the University of Massachusetts Amherst had waited only a few more years.

In truth however, the scientists discovered that these non-indigenous lizards had undergone remarkable evolutionary changes in only 36 years as they adapted to the new habitat. Duncan Irschick, a biologist from UMass Amherst explained, "Striking differences in head size and shape, increased bite strength and the development of new structures in the lizard's digestive tracts were noted after only 36 years, which is an extremely short time scale."

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Italian Wall Lizard (Podarcis sicula) before seclusion on Isla Nublar...

DNA analysis identified the lizards as identical to the species of the five adult pairs that were originally released on the island. Abundant but "tough and fibrous" plant life on their new home, the island of Pod Mrcaru, resulted in the development of bigger heads for increased bite force. Even more surprises...

(more below the fold)

...lay inside the lizards' stomachs, which had developed new structures called cecal valves, to help digest plant matter. These friendly little valves have never before been seen in Italian wall lizards.

"These structures actually occur in less than 1 percent of all known species of scaled reptiles," says Irschick. "Our data shows that evolution of novel structures can occur on extremely short time scales. Cecal valve evolution probably went hand-in-hand with a novel association between the lizards on Pod Mrcaru and microorganisms called nematodes that break down cellulose, which were found in their hindguts." Good times, great oldies...

i-822d996caee4ab36b0ac81aa1b0e8957-v lizard alien.jpg
Italian Wall Lizard (Podarcis sicula) after seclusion on Isla Nublar...

Published in the Proceedings of the National Academy of Sciences found via Physorg.

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Obligatory Creationist Comment: "Yeah, but it's still a lizard."

Sorry - had to beat 'em to the punch. :)

Seriously, this is way cool.

By Joe Shelby (not verified) on 18 Apr 2008 #permalink

Finally, definitive proof that evolution exists. Thank Allah!

And at UD, ID suck-toad DaveScot would mutter that they were designed and "front-loaded".

warning: layperson question follows.

do these changes have to be traced to genetics to rule out adaptation of individuals vs evolution of a species? i guess they could check newborns too?

"...the scientists discovered that these non-indigenous lizards had undergone remarkable evolutionary changes in only 36 years as they adapted to the new habitat."

Evolution and adaptation in the same sentence.

Are evolution and adaptation the same thing?

I adapt every time the the weather changes. I put on a jacket when it's cool. I wear shorts when it's warm.

Does this mean I have evolved into a new species over the last 53 years?

Just wondering.

Brian, that was either brilliant satire, or concrete evidence that you know nothing about either evolution or adaptation.

Please let me know which it is before I proceed to comment further!

I wonder if the changes would have been less dramatic if they had left a larger seed population (say a couple hundred pairs instead of five).

Why do the evolutionists interchange evolution, which requires new information, with adaptation, which doesn't require any new information? These same dopes should be shocked there are chihuahuas and St Bernards bred out of the same type known as a dog.

Some cogent comments here. Individual organisms have the possibility of individual adaptation without genetic change. For example, if you start lifting weights, you will get stronger without any change in your genetics. Is the asumption being made that the adaptations are so striking they must be due to change in genetic make up? However, it is not clear if this has been demonstrated. So we are left to wonder if we have an organism with a genome which allows these changes as individual adaptations, or if there has been a shift in the genetic make-up of the population (evolution) with regards to the genes involved in regulating these changes.

By Jim Thomerson (not verified) on 18 Apr 2008 #permalink

"Does this mean I have evolved into a new species over the last 53 years?" -Brian, comment above

Your adjusting to changing weather conditions is acclimatisation, not evolution. Acclimatisation works within the limits your body has for hot and cold (there is only so much cold you can take, and so much heat). Evolution would be a genetic change that altered your temperature limits, that could then be inherited by your children.

One way to test acclimatisation vs evolution in these lizards would to put some of these "evolved" ones back into their native environment and see how their offspring turn out. If its acclimatisation, the offspring born in the native environment should be the same as the original lizards. If there has been a genetic shift, the offspring should still show it.

Just my thoughts. Interesting post guys! :)

"DNA analysis identified the lizards as identical [!] to the species of the five adult pairs that were originally released on the island."

"Identical" means they are not a new species. This suggests that the cecal valve structures are latent in their original genetic material. (Who knows what our appendix is really for?) There is much to suggest that a large part of morphological development is determined by whether certain parts of genetic structure are "turned on".

As another poster made the point, do we look at a Chihuahua and a Great Dane and conclude they are different species? Is hairlessness an "adaptation" or an "evolution"? Now, growing a pineal eyeball would have been more interesting...

By Michael J. Dunn (not verified) on 19 Apr 2008 #permalink

so where in this research/post do we claim this is a new species?

"DNA analysis identified the lizards as identical [!] to the species of the five adult pairs that were originally released on the island."

Michael J. Dunn - identical here does not mean "identical." It's funny that you would seize on that without realizing that the lizards are obviously not clones of each other. The only way to get identical genomes in two different individuals would be if the two were identical twins, and even in that case there is probably a copying error somewhere that makes them not "identical."

How could you not think about the basics of meiosis before posting that? During meiosis, a stage called "crossing over" occurs wherein the chromatids exchange alleles back and forth. The end result is a never before seen sequence of dna.

Have you never heard of this before? If you have, then you should have understood the context of the term "identical" and realized what exactly it pointed at.

I speculate what is meant by "identical' is that the parent population has a certain genetic make up for a few sequences which have been examined. The island population showes no changes in these particular sequences. If one were to compare other sequences, related to the morphological changes seen, differences might be found.

A sort of side comment. Some evolution has occurred. The genetic makeup of the new island population is different from that of the parent population due to sampling error. I read that the original new population comprised five pairs, 10 individuals, 20 sets of genetic loci.

Suppose in the parent population there was an allele with a frequency of 1/1000, a fairly rare allele. In the new population it has a frequency of either 0 or 1/20 or more. So the founder population has undergone major shifts in frequency of rare alleles. Well, suppose there is an allele with a frequency of 1/2, but it happened that your founder population has 15/20 or 5/20; just luck of the draw. This is the founder effect that you see in the literature.

By Jim Thomerson (not verified) on 21 Apr 2008 #permalink

What we have here is a situation which fits the allopatric speciation model very nicely. We have a small population geographically isolated from the parent population and facing different selection pressures. At this time we have morphological divergence, but we do not yet have two species. Are we seeing the early stages of a speciation event which will create two separate species (by whatever species criteria you like)? Can we, at this point in time make a firm decision that speciation is or is not happening?

By Jim Thomerson (not verified) on 21 Apr 2008 #permalink

I highly suggest reading "The Beak of the Finch" to explain this. It's a very interesting read. :)


This is the most obvious case of jumping to conclusions I've ever read. I predict this will not last a year before debunked. It's not evolution, its simple adaptation. Take some wall lizards, put them in a terrarium, feed them plants and check every once in while for cecal valves. This probably happens with most lizards very quickly.

By courageousjake (not verified) on 27 Feb 2009 #permalink

Epigenetics could provide a link between adaptation and evolution. This is easy to imagine in microbes and plants in which there is not a clear distinction between germ cells and somatic cells, but is more difficult to imagine in animals.