![]() ![]() "The logical next step would be to confirm the genetic basis for these changes.Bayonets, machetes, axes, firearms, swords "All of this might be evolution," Hendry said. "That kind of change is really dramatic," he added. There's no dispute that major changes to the lizards' digestive tract occurred. What could be debated, however, is how those changes are interpreted-whether or not they had a genetic basis and not a "plastic response to the environment," said Hendry, who was not associated with the study. ![]() The study demonstrates that a lot of change happens in island environments, said Andrew Hendry, a biology professor at Montreal's McGill University. While researchers do know the invader's impact on its reptile brethren, they do not know how the species impacts local vegetation or insects, a subject of future study, Irschick said. What's most important is how fast this is," he said. It would be akin to humans evolving and growing a new appendix in several hundred years, he said. Such physical transformation in just 30 lizard generations takes evolution to a whole new level, Irschick said. ![]() The lizard also dropped some of its territorial defenses, the authors concluded. For one, the plentiful food sources allowed for easier reproduction and a denser population. The rapid physical evolution also sparked changes in the lizard's social and behavioral structure, he said. (Related news: "Komodo Dragon's Bite Is 'Weaker Than a House Cat's'". "This was a brand-new structure."Īlong with the ability to digest plants came the ability to bite harder, powered by a head that had grown longer and wider. "They evolved an expanded gut to allow them to process these leaves," Irschick said, adding it was something that had not been documented before. 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. Physically, however, the lizards were not built to digest a vegetarian diet. Pod Mrcaru, for example, had an abundance of plants for the primarily insect-eating lizards to munch on. The transplanted lizards adapted to their new environment in ways that expedited their evolution physically, Irschick explained. The new species wiped out the indigenous lizard populations, although how it happened is unknown, he said. The new habitat once had its own healthy population of lizards, which were less aggressive than the new implants, Irschick said. The findings were published in March in the journal Proceedings of the National Academy of Sciences. "The island was swarming with lizards," he said. We had no idea if the original introductions were successful," Irschick said. "We didn't know if we would find a lizard there. (Read: "Kayaking the New Croatia" in National Geographic Adventure Magazine.) In 2004, however, tourism began to open back up, allowing researchers access to the island laboratory. The researchers couldn't get back to island because of the war, Irschick said. 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.Īfter scientists transplanted the reptiles, the Croatian War of Independence erupted, ending in the mid-1990s. (Related: "Evolution's 'Driving Force' Shifts Based on Behavior, Study Says". 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. 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. ![]() 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. 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. ![]()
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