DISSERTATION RESEARCH: Rapid evolution and the character displacement hypothesis: a unique test using a replicated natural colonization experiment

Harvard University, Cambridge MA

Investigators

Abstract

According the character displacement hypothesis, similar species that use similar resources and come to live in the same area should evolve differences that allow them to coexist. Otherwise, one species will drive the other species extinct. This research tests for character displacement in the lizard Anolis carolinensis in response to the recent invasion of a closely related species, A. sagrei. The two species compete for food and space, so the researchers expect them to evolve to use different resources now that their geographic ranges overlap. The researchers are using a replicated island experiment to test this hypothesis, comparing habitat use patterns and physical characteristics of A. carolinensis on islands where A. sagrei is present to control islands where A. sagrei is absent. This research, the first replicated experimental test of the character displacement hypothesis in nature, will serve as a clear example of evolution in action, useful to teach evolutionary principles to the general public and to help dispel the popular notion that evolution by natural selection is a slow process. This research examines the role that small-scale evolutionary processes may play in generating large-scale evolutionary patterns, and the investigators will describe the results in popular scientific articles, public museum exhibits, and high-school science curricula. As a study of rapid evolution in response to environmental change, this research will inform conservation biologists and policy makers who are developing measures to conserve species and ecosystems in the face of an increasing human population, climate change, invasive species, and habitat destruction.