HackingTheUniverse

Evolution can take place in a shorter time span than scientists previously thought, according to a study of lizards that were transplanted into a new environment, then left alone for thirty-six years. Could a similar process be accomplished in a laboratory environment designed to stimulate specific evolutionary adaptations?

Rapid Evolution Driven by Invasion into New Habitats – [scienceblogs.com]

Evolution has long been thought to occur slowly, due to small and gradual genetic changes that accumulate over millions of years until eventually, a new species arises. However, recent research has been calling this assumption into question. According to a study that was just published by an international team of scientists, dramatic physical changes can occur very rapidly — on the order of just 30 generations in this case.

To document adaptation and evolution, a group of researchers moved a small group of lizards from their original island home island to a nearby island in 1971. Just five male and five female Italian wall lizards, Podarcis sicula, were translocated from the islet of Pod Kopiste to the nearby islet of Pod Mrcaru, both of which belong to Croatia and are located in the southern Adriatic Sea.

Thirty-six years later, after the Croatian war ended, another team of scientists finally returned to the island to check on the reptilian translocations and were surprised to find that the island was teeming with their descendants.

Lizards Undergo Rapid Evolution after Introduction to a New Home, Says UMass Amherst Researcher – [umass.edu]

“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.”

Lizards Rapidly Evolve After Introduction to Island – [evolutiondiary.com]

Fast-Track Evolution

The new habitat once had its own healthy population of lizards, which were less aggressive than the new implants, Irschick said.

The new species wiped out the indigenous lizard populations, although how it happened is unknown, he said.

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.