Lizards Rapidly Evolve After Introduction to Island

Kimberly Johnson
for National Geographic News
April 21, 2008

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.

(Related: "Evolution's 'Driving Force' Shifts Based on Behavior, Study Says" [November 16, 2006].)

Lizard Swarm

While the experiment was more than 30 years in the making, it was not by design, according to Duncan Irschick, a study author and biology professor at the University of Massachusetts, Amherst.

After scientists transplanted the reptiles, the Croatian War of Independence erupted, ending in the mid-1990s. The researchers couldn't get back to island because of the war, Irschick said.

In 2004, however, tourism began to open back up, allowing researchers access to the island laboratory.

(Read: "Kayaking the New Croatia" in National Geographic Adventure Magazine.)

"We didn't know if we would find a lizard there. We had no idea if the original introductions were successful," Irschick said.

What they found, however, was shocking.

Continued on Next Page >>


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