Who says evolution is slow?

I love stories like this. In 1971, five pairs of lizards were moved from one island in the Adriatic Sea to another, as part of an experiment in evolution. The lizards’ original home harbored a lot of insects, and their adopted island did not. Political upheaval rendered the new island off limits until 2005, and when the researchers returned, they found lizards in spades, but with several important modifications.

First, the lizards heads had become larger in all dimensions, to facilitate greater biting force. This was consistent with the observation that the lizards now subsisted on plant matter instead of insects. Second, and more amazingly, the lizards evolved novel structures in their digestive systems. These “cecal valves” created fermentation chambers where symbiotic microbes helped break down the lizards’ food. According to the researchers, such rapid arisal of an entirely novel feature has never been documented before.

This is an immensely exciting study. Novel features have been seen to evolve before (the nylon eating bacteria are a perennial favorite), but never has such a complex novel feature as these lizards’ cecal valves arisen right under the noses of researchers. The power of natural selection to adapt organisms to changing conditions is shown again and again to be even more mind-boggling than we thought.

Tags: allopatric speciation, cecal valves, Evolution, italian wall lizard, pod mrcaru, rapid evolution, rapid speciation