Fast-Tack Evolution

Posted by jns on 1 May 2008

The story, as it’s told online in National Geographic News,^* goes like this.

n 1971, scientists transplanted five adult pairs of [Italian wall lizards] from their original island home in Pod Kopiste to the tiny neighboring island of Pod Mrcaru, both in the south Adriatic Sea[, off the coast of Croatia].

Genetic testing on the Pod Mrcaru lizards confirmed that the modern population of more than 5,000 Italian wall lizards are all descendants of the original ten lizards left behind in the 1970s.

However, the Pod Mrcaru/Italian wall lizards of today are no longer much like the original pair. It seems that the population has evolved some new digestive strategies–and parts!–along with a different head with a stronger jaw to go along with the new strategy. All this they managed to do in only 30 generations on the island.

As the report says, all of the current lizards have been tested genetically and are known to be descended from the original pair. It also turns out that the new lizards have displaced the aboriginal lizards on the island when the first pair were transplanted. There is no determination mentioned about whether the new lizard is a different species from the original pair.

Isn’t that interesting! Evolution in action, and on a surprisingly short time scale. How can this be possible though? Doesn’t evolution take ages and ages to accomplish change?

Yes and no. As our understanding of evolution (and natural selection) improves and deepens, it seems that evolution is anything but uniformly slow and uniformly steady.^# Indeed, the more modern understanding is coming to terms with how genetic information is prepared, as it were, to make rapid changes when the occasion arises. Some of this is touched on in Sean Carroll’s book Endless Forms Most Beautiful.

Of course there is a political aspect to this report of scientific findings. Some evolution deniers will continue to deny that speciation is possible through evolution, but they will be seen to be wrong, probably sooner rather than later, too.
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^*Kimberly Johnson, “Lizards Rapidly Evolve After Introduction to Island“, National Geographic News, 21 April 2008.

^#Although I don’t really see the need to turn to the concept of Punctuated Equilibrium, as promoted by Eldredge & Gould to incorporate the nonuniformity. Doing so seems to me to caricature any realistic understanding of gradualism.