Using experiments in nature to study evolution in real time: research on lizard adaptation in the Bahamas

Losos, Jonathan B.

losos@wustl.edu

Department of Biology

Washington University

St. Louis, Missouri USA

Biologists used to think that evolution proceeded at a glacial pace, so slow that change could only be detected over the span of eons. We now know that this view is wrong. Quite the contrary, when environments change and natural selection pressures are strong, evolution can occur very quickly, rapidly enough to be detected over short periods. A corollary of this finding is that the experimental method, the gold standard of scientific research, can now be applied to test evolutionary hypotheses. In this talk, Jonathan Losos describes a 30-year experimental evolution research program studying lizard adaptation to changing conditions in the Bahamas. The work is based on detailed studies of the evolution of the 400-species-rich lizard genus Anolis which has diversified throughout the Caribbean and Central and South America. Based on understanding of how species have adapted over thousands and millions of years, Losos and colleagues designed experiments to test the hypothesized drivers of evolutionary change. To do so, the researchers introduced lizards to small islands in the Bahamas (the species are native to the area and regularly colonize and become extinct on small islands, so the research was emulating a natural, ongoing process). The researchers then monitored evolutionary change of the populations through times. Despite the intervention of too many hurricanes, the researchers documented that natural selection pressures can be intense and that, correspondingly, lizard populations evolve rapidly and in the predicted direction.