Supplementary Materials for Rapid evolution of a native species following invasion by a congener

Making adjustments for a new neighborhood Competition between species drives the acquisition of diversity. Stuart et al. introduced a non-native anole lizard to natural experimental islands. In response, the original inhabitants adopted higher perches in the trees, where the larger invader was at a disadvantage. Within about 3 years—or 20 generations—the shift led to inherited morphological changes in the native lizards, including their growing larger toepads. Science, this issue p. 463 On small islands in Florida, native lizards adapt to higher perches following invasion by a related species. In recent years, biologists have increasingly recognized that evolutionary change can occur rapidly when natural selection is strong; thus, real-time studies of evolution can be used to test classic evolutionary hypotheses directly. One such hypothesis is that negative interactions between closely related species can drive phenotypic divergence. Such divergence is thought to be ubiquitous, though well-documented cases are surprisingly rare. On small islands in Florida, we found that the lizard Anolis carolinensis moved to higher perches following invasion by Anolis sagrei and, in response, adaptively evolved larger toepads after only 20 generations. These results illustrate that interspecific interactions between closely related species can drive evolutionary change on observable time scales.