Invasive colonise and spread widely in places where they are not normally found. It affects native species by eating them, out-competing them and intriguing unfamiliar parasites and pathogens. For example, the invasive kudzu plant, native to Southeast Asia, overgrows seemingly anything in its path in the southeast US. Natural selection wrought by invasive species can often be strong, and natives will either go extinct or adapt. During adaptation, selection favours those individuals with characteristics that allow them to survive and reproduce in the face of the invader. The offspring of the survivors will inherit their parents' beneficial traits, and the population will evolve. In the 1950s, the brown anole lizard, Anolis arrived in South Florida from Cuba. The effects of this invasion might not be very noticeable to humans. But the brown anole certainly makes an impression on Florida's only native anole species, the green anole, Anolis Carolinensis. This is because the green and the town anoles enjoy similar lifestyles. They eat similar food—mostly insects and spiders—and use similar habitats—the ground and lower parts of trees and bushes. Because of these similarities, we expect the invasive brown anole to impose strong natural selection on the native green. Previous researchers had observed that green anoles living with brown anoles tend to live higher up in the trees, presumably to escape competition for food and space. To obtain definitive evidence, our research team conducted an experiment on the small, man-made islands near Cape Canaveral. In 1995, we introduced the brown anole to three islands that— until then—had only green anoles. Within a few months, the green anole moved up into the trees and stayed there.