Sometimes, evolutionary selection can happen within a single generation of a species, research now shows. In response to a new predator, lizards on several Caribbean islands underwent selection first for long legs and then for short legs.
When the brown anolis lizard (Anolis sagrei) lives free of predators, it stays mostly on the ground, where long legs make for fast moves. But when preyed upon, the lizard tends to move up into trees and bushes, where shorter legs are good for climbing.
Jonathan B. Losos of Washington University in St. Louis and his colleagues report in the Nov. 17 Science that they introduced the curly-tailed lizard (Leiocephalus carinatus), which eats the brown anolis, onto six baseball diamond–size islands where the brown anolis lives in the Bahamas. The predator had also been indigenous there but had been swept away by hurricanes.