Competition affects evolution in island lizards

WASHINGTON - Millions of years before human beings began battling it out over beachfront property, a similar phenomenon was unfolding in a diverse group of island lizards.

Often mistaken for chameleons or geckos, Anolis lizards fight fiercely for resources, responding to rivals by doing push-ups and puffing out their throat pouches.

But anoles also compete in ways that shape their bodies over evolutionary time, says a new Harvard study.

Anolis lizards colonised the Caribbean from South America some 40 million years ago and quickly evolved a wide range of shapes and sizes.

“When anoles first arrived in the islands there were no other lizards quite like them, so there was abundant opportunity to diversify,” said study author Luke Mahler of Harvard University.

Free from rivals in their new island homes, Anolis lizards evolved differences in leg length, body size, and other characteristics as they adapted to different habitats, said a Harvard release.

Today, the islands of Cuba, Hispaniola, Jamaica and Puerto Rico - collectively known as the Greater Antilles - are home to more than 100 Anolis species, ranging from lanky lizards that perch in bushes, to stocky, long-legged lizards that live on tree trunks, to foot-long ‘giants’ that roam the upper branches of trees.

“Each body type is specialised for using different parts of a tree or bush,” said Mahler.

The team’s findings are slated for publication in Evolution.