Ecological Opportunity and the rate of evolution in Caribbean Anolis Lizards

Abstract

A major question in evolutionary biology is whether ecological interactions among species affect the rate of evolution as organisms diversify. According to the ecological opportunity hypothesis, evolution occurs most rapidly in the absence of competition, and slows as competitors accumulate during diversification. I tested this hypothesis by measuring the rate of evolution in radiations of Anolis lizards on the four Greater Antilles islands. As predicted, anoles on these islands exhibited an early burst of evolution in traits important for habitat use, and the rate of evolution subsequently declined. It is less clear whether ecological opportunity has affected the rate of evolution in radiations of anoles in mainland South America and Central America. Although this relationship remains poorly understood, preliminary studies suggest that mainland anoles are at least as diverse in morphology and ecology as their island counterparts.