Leapin’ Lizards

Credit: Yoel Stuart

On small islands in Florida, a native species of green anole lizards quickly changed behavior—and more—after an invasive species of brown anole lizards came to inhabit the same islands. UT Austin postdoctoral researcher Yoel Stuart observed the green anoles perching higher in trees, as they competed for food and space with the newcomers (and maybe also because brown anoles eat green anole hatchlings). In just 15 generations or about 20 years, the green anoles had rapidly evolved to become better at gripping the higher-up branches, with larger toe pads that helped their feet to cling. “The speed of the evolutionary response surprised us,” Stuart says, “but it reinforced the growing notion that, when survival and reproduction depend on it, evolution can take place in just a few generations.”