Testing the island effect in adaptive radiation:rates and patterns of morphological diversificationin Caribbean and mainland Anolis lizards

摘要

Many of the classic examples of adaptive radiation, including Caribbean Anolis lizards, are found onislands. However, Anolis also exhibits substantial species richness and ecomorphological disparityon mainland Central and South America. We compared patterns and rates of morphological evolution toinvestigate whether, in fact, island Anolis are exceptionally diverse relative to their mainland counterparts.Quite the contrary, we found that rates and extent of diversification were comparableAnolis adaptiveradiation is not an island phenomenon. However, mainland and Caribbean anoles occupy different parts ofmorphological space; in independent colonizations of both island and mainland habitats, island anoleshave evolved shorter limbs and better-developed toe pads. These patterns suggest that the two areas are ondifferent evolutionary trajectories. The ecological causes of these differences are unknown, but may relateto differences in predation or competition among mainland and island communities.