Wednesday, April 23, 2008

Wowee wowee whoa wow!

Evolution in action, folks! In just 36 years, we've got a brand-new kind of lizard!

Here's the short version: In 1971, scientists transplanted just five pairs of a kind of lizard (lets call them Reds) from Pod Kapiste (an island) to a neighboring island (Pod Mrcaru). Mrcaru already had its own species of lizard (Blues). Then, the Croation War erupted, and the islands were abandoned for some 36 years. In 2004, tourists were allowed back toe Kapiste and Mrcaru, so the scientists returned, eager to see whether the ten original lizards populated the island or simply vanished. During the human war, a lizard war apparently also broke out, and the Reds completely eradicated the Blues. The Reds, however, were now stuck on an island of lush vegetation--and they were insectivores. What to do?

Well, within just 30 generations (give or take), the Reds developed stronger, wider skulls (for eating plants), shorter legs, and "cecal valves," unique muscular chambers in the intestine which closed off further movement down the tube and allows the plant material to ferment, thus allowing the lizards to digest the tough plant material. The cecal valves are entirely novel structures, not present in the Red's Kapiste ancestors.

What's more, the easy access to food resulted in a drop in the Red's aggressive behavior and a population boom. And don't worry--genetic tests have confirmed that the Reds are decended from their Kapiste ancestors...this isn't some new lizard floating across the sea.

So the bottom line is that in just 36 years, these once insectivorous, aggressive lizards have become herbivorous, gut-fermenting, passive lizards. In just 36 years!

That shows two important things: Evolution by natural selection works, and it works quickly. No Designer necessary! If anybody has a copy of the paper (thanks for the open access, PNAS!), please send it my way!


BusaFan said...

Because only one kind of lizard can live on any one island at a time.

Zach said...

What? How is that relevant? Did you read the article? I can send you the paper if you want, as one of my readers graciously sent it my way.

ScottE said...

Busafan: could you offer some sort of clarification on your comment? It doesn't really make sense to me.