Sunday, June 1, 2008 | Reason : In the News | print version

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Lizards make adaptive change

by Stan Freeman

Thanks to Larry Clark for the link.

Lizards make adaptive change

AMHERST - In 1971, five pairs of Italian wall lizards were transplanted by biologists from their home island of Pod Kopiste, in the South Adriatic Sea, to the neighboring but subtly different island of Pod Mrcaru, where none lived, as an experiment in evolution.

How, if at all, would these creatures change?

Largely insect eaters, the half-foot long reptiles would find themselves on an island where insects were in short supply but plants were not.

Because of political upheaval in the region - the Adriatic Sea borders Croatia - it was not until 2004 that Duncan J. Irschick, a professor of biology at the University of Massachusetts here, and a team of international biologists could return to find out what had happened to the lizards.

"As a scientist, it was a once in a lifetime opportunity. Historical circumstances prevented people from going back to the island for a very long time. So when we first went out there in 2004, we didn't know what we would find. We chartered a boat out to the island, and it was amazing. It was swarming with lizards," he said.

Pod Mrcaru, just off the west coast of Croatia, is a "tiny rock in the middle of the water," Irschick said.

"You could walk from one end to the other in five minutes. It has a Mediterranean climate - hot and very dry. It's mainly rock with little shrubby plants sticking up out here and there. It looks very inhospitable," he said.

They found on that visit and subsequent trips in 2005 and 2006 that the wall lizards had changed dramatically in the intervening decades. Results of their study were published March 25 in the "Proceedings of the National Academy of Sciences."

Two of the most striking changes were the increase in head size and the change in head shape.

"Individuals on Pod Mrcaru have heads that are longer, wider and taller than those on Pod Kopiste, which translates into a big increase in bite force," Irschick said.

"Because plants are tough and fibrous, high bite forces allow the lizards to crop smaller pieces from plants, which can help them break down the indigestible cell walls," he said.

Most importantly, though, the researchers discovered the digestive tracts of the lizards had changed. They were now divided, creating a fermentation chamber where microbes could break down the toughest portions of the plants.

"What was unique about this study was that the lizards developed brand new structures, a part of their gut called a 'cecal valve' (which separates the chambers). No one had ever documented that kind of change before," Irschick said.

"It's good evidence that not only can evolution happen rapidly, but animals can evolve new structures as well (in a short time span)," he said.

To confirm that the lizards were descendants of the 10 individuals introduced to the island, the researchers conducted a DNA analysis and found they were genetically identical to the original ones.

The research was supported by the National Science Foundation and the Fund for Scientific Research in Flanders. Additional members of the study team included researchers from Harvard University, University of Antwerp, the Royal Belgian Institute of Natural Sciences and the Croatian Natural History Museum.

Posted: Sunday, June 1, 2008 | Permalink

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1. Comment #187241 by Count von Count on June 1, 2008 at 3:32 pm

We chartered a boat out to the island, and it was amazing. It was swarming with lizards.

This is a very interesting discovery. Now if only religious people could charter a boat to reality. They might find it swarming with evidence!

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2. Comment #187243 by unmolested.altar.boy on June 1, 2008 at 3:43 pm

I've been curious about this and have yet to find good information, but why was this project forgotten, abandoned, neglected for so long?

Every source I've read blames it on the war, but the Homeland War did not start until 1991. Best I can guess is that someone involved in the project was cashiered as a result of the post Croatian Spring purges and nobody thought to follow up.

Anyway, if anyone can recommend a source or has more information, I'd be most obliged.

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3. Comment #187244 by phil rimmer on June 1, 2008 at 3:44 pm

Ah, y'see, but it didn't happen in the lab. So it doesn't really count. It can't be scientific. And besides I've got my eyes closed and my hands over my ears. "Jebus wants me for a sunbeam...tra la.."

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4. Comment #187252 by rod-the-farmer on June 1, 2008 at 4:35 pm

This is only micro-evolution, saeth the fundies. Until they change into eagles, evolution is wrong, and goddidit - QED. What was missing was a note about the typical generation time of these lizards. How long before they are sexually mature, and produce offspring ? Suppose for the moment it is 12 months, and the time allotted was then about 35 years, or 35 generations. That is fairly quick for so many substantial changes, I think, not being a trained biologist. Especially since this was NOT done in a lab, where you could select those which are different, and separate them....as opposed to merely observing, and letting natural selection take place. Vewy intewesting.

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5. Comment #187259 by Spitzmutt on June 1, 2008 at 5:05 pm

The link to the article is

http://www.masslive.com/news/republican/index.ssf?/base/news-2/121230487689120.xml&coll=1

Thanks,

Larry = Spitzmutt

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6. Comment #187260 by kraut on June 1, 2008 at 5:06 pm

You guys all got it wrong: godditit.
He couldn't see the poor lizard starving, so he changed 'em. Gawd, are you folks stupid.

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7. Comment #187265 by coodgee on June 1, 2008 at 5:44 pm

quote: This is a very interesting discovery. Now if only religious people could charter a boat to reality. They might find it swarming with evidence!

is this really necessary?

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8. Comment #187266 by freiversuch on June 1, 2008 at 5:46 pm

they were genetically identical to the original ones

So I guess they didn't sequence the whole DNA but were just looking at markers?

Would be interesting to know, how much the DNA really changed to allow for all these tremendous adaptations.
Or was it all phenotype?

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9. Comment #187267 by Abhishek on June 1, 2008 at 5:46 pm

the researchers conducted a DNA analysis and found they were genetically identical to the original ones.

I'm assuming they mean "genetically identical" = DNA was ALMOST identical? If it really was entirely identical, there wouldn't be anatomical and functional differences in the lizards.

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10. Comment #187275 by steveroot on June 1, 2008 at 6:30 pm

7. Comment #187265 by coodgee on June 1, 2008 at 5:44 pm
quote: This is a very interesting discovery. Now if only religious people could charter a boat to reality. They might find it swarming with evidence!

is this really necessary?

A little "pinchee-winchee" on our toes? ;-)
Ste5e

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11. Comment #187281 by Lightnin on June 1, 2008 at 6:47 pm

So I guess they didn't sequence the whole DNA but were just looking at markers?

Well they certainly wouldn't sequence the entire genome of individual lizards, that takes a great deal of time and money.

The tricky thing is the difference between two alleles of one gene could just be one base-pair out of a few thousand. So studying the phenotypic difference is just as, if not more relevent to understanding morphological differences. Not that I'm a scientician or anything.

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12. Comment #187289 by Wosret on June 1, 2008 at 7:41 pm

They had this up already on here didn't they? If not this adds no new information. Didn't the last article have pictures?

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13. Comment #187291 by mordacious1 on June 1, 2008 at 7:50 pm

hmmm I wonder how far off shore these guys are. Obviously there's not a lot of food and they may figure a way to transport themselves to the shore where they aren't a native species. Not always a good thing.

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14. Comment #187301 by Cartomancer on June 1, 2008 at 9:02 pm

I am very impressed by this. I never knew that evolutionary changes in complex vertebrates could be quite so dramatic in such a short time. I always used to think that evolutionary change was glacially slow in anything but rapidly reproducing bacteria, but apparently this is not so.

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15. Comment #187319 by PJG on June 1, 2008 at 11:39 pm

rod-the-farmer is right. This is remarkable if these changes happened in just 35 generations - or even doubling it to 70 generations - from just five pairs. There is something about this article that makes me feel uneasy. I feel there is more to this than meets the eye - or the article itself is misrepresentative of the research.

Has anyone seen the actual paper?

Abstract:

Rapid large-scale evolutionary divergence in morphology and performance associated with exploitation of a different dietary resource

Anthony Herrel*,,, Katleen Huyghe, Bieke Vanhooydonck, Thierry Backeljau,, Karin Breugelmans, Irena Grbac¶, Raoul Van Damme, and Duncan J. Irschick||

*Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138; Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610 Antwerpen, Belgium; Royal Belgian Institute of Natural Sciences, Vautierstraat 29, B-1000 Brussels, Belgium; ¶Department of Zoology, Croatian Natural History Museum, Demetrova 1, HR-1000, Zagreb, Croatia; and ||Department of Biology and Organismic Evolutionary Program, University of Massachusetts at Amherst, 221 Morrill Science Center, Amherst, MA 01003

Edited by Gordon H. Orians, University of Washington, Seattle, WA, and approved January 31, 2008 (received for review December 19, 2007)

Although rapid adaptive changes in morphology on ecological time scales are now well documented in natural populations, the effects of such changes on whole-organism performance capacity and the consequences on ecological dynamics at the population level are often unclear. Here we show how lizards have rapidly evolved differences in head morphology, bite strength, and digestive tract structure after experimental introduction into a novel environment. Despite the short time scale (36 years) since this introduction, these changes in morphology and performance parallel those typically documented among species and even families of lizards in both the type and extent of their specialization. Moreover, these changes have occurred side-by-side with dramatic changes in population density and social structure, providing a compelling example of how the invasion of a novel habitat can evolutionarily drive multiple aspects of the phenotype.

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16. Comment #187324 by freiversuch on June 2, 2008 at 12:17 am

So studying the phenotypic difference is just as, if not more relevent to understanding morphological differences

Hi Lightnin, I agree, that this study is very important and the results are extremely exciting. Just trying to satisfy my reductionist cravings, heh.

I have had many a discussions with Christians that argued from this angle of phenotype and denied this kind of change in the genotype. I know this argument is nonsense but a thorough DNA analysis would lay any doubts at rest for good and give a very very powerful layman argument for evolution.

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17. Comment #187333 by bachfiend on June 2, 2008 at 1:16 am

It is interesting that caecal valves develop so quickly in response to a change in diet, but I have my doubts. Humans taking non-steroidal anti-inflammatory drugs for long periods develop intestinal webs and diaphragms (which look a bit similar to the caecal valves) and which look so well-formed as if they were a "normal" structure (occasionally children without a history of NSAID use develop identical structures, so there must be other causes in the diet). I suppose one way of deciding would be to take a control population of the new lizards and feed them on the old diet and see if they still have the caecal valves.
I find the Russian work on the tame silver fox (referred to in the Ancestor's Tale) much more interesting. See:
http://cbsu.tc.cornell.edu/ccgr/behaviour/02_Movies/tame1_04.MPG

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18. Comment #187421 by AKirkland on June 2, 2008 at 6:03 am

In response to the last comment, a question - do ALL people who take NSAID form this phenomenon? My point being that even if the supposed new intestinal structure is a result of an existing effect, if it now offers an advantage then we will still see a significant change in the proportion of the population who have this affliction. I actually find this idea fascinating in this case - it could have been the result of a random mutation which lay dormant for a long time until it became useful all of a sudden, and then the scaffolding which supported it (i.e. the cause, such as the strange diet) has been removed and they may still retain the trait if they were fed differently. I hope the scientists investigate the idea.

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19. Comment #187920 by bachfiend on June 3, 2008 at 3:49 am

The reason for intestinal webs and diaphragms with NSAIDs is a bit prosaic. Pharmaceutical companies just love enterically coating their nasty products to delay the side effects. The enteric coating forms a gooey sticky mess which sticks to the mucosa in the bowel causing an ulcer, and subsequent tablets tend to stick at the same spot(s) and the repair causes the webs etc. If there is something toxic in the lizards' new diet, it could be causing the same thing. I still think the easiest thing to do would be to see if the caecal valve persists in the lizards if they are fed on their original diet.

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20. Comment #187991 by InfuriatedSciTeacher on June 3, 2008 at 5:50 am

[12. Comment #187289 by Mitchell Gilks on June 1, 2008 at 7:41 pm

They had this up already on here didn't they? If not this adds no new information. Didn't the last article have pictures? ]

I think I know what you're referring to... There was an NY Times Article that discussed rapid evolution in lizards, but those were in the Carribean. Being new to this site I don't know if it was ever linked here or not, but..

Leapin' Evolution Is Found in Lizards 1 May 1997, Nicholas Wade.

Sorry, having link issues, but you can query it.

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21. Comment #188088 by bluebird on June 3, 2008 at 8:00 am

This subject was posted a little while back (see:archives4/20/08)...but I'm pleased it's posted again since I didn't read it the first time around.

Above mentioned article also interesting:
http://query.nytimes.com/gst/fullpage.html?res=9403E3DC1E31F932A35756C0A961958260&sec=&spon=&pagewanted=all

Leapin' Lizards I find these critters quite intriguing & appealing!!

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22. Comment #188976 by irate_atheist on June 5, 2008 at 5:13 am

22. Comment #188972 by garywheron -

I guess that this also supports their view...

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23. Comment #188983 by Peribolos on June 5, 2008 at 6:07 am

While the results of this study are fascinating I do have to question how ethical it was to dump an alien species on a small island and watch them overrun it.

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24. Comment #188986 by black wolf on June 5, 2008 at 6:30 am

Ah, yes, AiG grasping at straws again. Have they got any evidence how the marsupial 'kind' evolved kangaroos, mice, bears and wolves within 6,000 years and moved the whole lot to Oz yet? Or did these species all evolve from different 'kinds' - each from just one breeding pair - and miraculously all ended up on the same continent? Or how each generation of the Ark's 'kinds' had to split into about 10,000 different species to explain the number we know today?
What I would like to see is a psychologist's explanation (in team with the theologians) why a group of people like AiG submit to stampeding moronity and happily gallop deeper in every year.

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