Italian wall lizards introduced to a tiny island off the coast of Croatia are evolving in ways that would normally take millions of years to play out, new research shows.
In just a few decades the 5-inch-long (13-centimeter-long) lizards have developed a completely new gut structure, larger heads, and a harder bite, researchers say.
In 1971, scientists transplanted five adult pairs of the reptiles from their original island home in Pod Kopiste to the tiny neighboring island of Pod Mrcaru, both in the south Adriatic Sea.
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.
The transplanted lizards adapted to their new environment in ways that expedited their evolution physically, Irschick explained.
Pod Mrcaru, for example, had an abundance of plants for the primarily insect-eating lizards to munch on. Physically, however, the lizards were not built to digest a vegetarian diet.
Researchers found that the lizards developed cecal valves—muscles between the large and small intestine—that slowed down food digestion in fermenting chambers, which allowed their bodies to process the vegetation's cellulose into volatile fatty acids.
"They evolved an expanded gut to allow them to process these leaves," Irschick said, adding it was something that had not been documented before. "This was a brand-new structure."
Along with the ability to digest plants came the ability to bite harder, powered by a head that had grown longer and wider.
Let's see your intelligent designer do that!