More Quick Evolving Lizards

In just 36 years since being relocated by biologists from their home island of Pod Kopiste, in the South Adriatic Sea, to the neighboring island of Pod Mrcaru, a population of Italian wall lizards (Podarcis sicula) have undergone rapid evolutionary change in both physical appearance and internal structure.

Striking differences in head size and shape, increased bite strength and the development of new structures in the lizard’s digestive tracts were noted after only 36 years, which is an extremely short time scale,” says Duncan Irschick, a professor of biology at the University of Massachusetts Amherst. “These physical changes have occurred side-by-side with dramatic changes in population density and social structure.”

Because the lizard’s diet has changes to roughly two-thirds plant food, they’ve evolved longer and wider heads than their Pod Kopiste counterparts. Most interesting though is the changes in their digestive tract as a result of having to eat mostly plant food. They’ve developed fermentation chambers in their gut so microbes can break down harder to digest parts of plants.

Examination of the lizard’s digestive tracts revealed something even more surprising. Eating more plants caused the development of new structures called cecal valves, designed to slow the passage of food by creating fermentation chambers in the gut, where microbes can break down the difficult to digest portion of plants. Cecal valves … have never been reported for this species, including the source population on Pod Kopiste.

“These structures actually occur in less than 1 percent of all known species of scaled reptiles,” says Irschick. “Our data shows that evolution of novel structures can occur on extremely short time scales.”

Via: Science Daily
Image Credit: Anthony Herrel of the University of Antwerp

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