Meeting Abstract

67.5  Saturday, Jan. 5  Testing for exceptional among-island convergence in Greater Antillean Anolis: introduction and application of a novel comparative method MAHLER, D. L.*; INGRAM, T.; REVELL, L. J.; LOSOS, J. B.; Univ. of California, Davis; Harvard Univ.; U. Mass., Boston; Harvard Univ.

Replicated adaptive radiations suggest that diversification may be strongly deterministic, even over macroevolutionary timescales. However, species-rich clades are expected to produce many convergent species by chance alone, such that the convergence we observe among selected species pairs in “replicated radiations” may be nothing more than a by-product of extensive diversification. To date, there have been few studies of clade-wide convergence, and these have tended to examine only those species that are most obviously similar. It thus remains to be determined whether the similarity of these clades is due to deterministic adaptive convergence. To test this hypothesis, we investigated patterns of trait evolution in Greater Antillean Anolis lizards, a group famous for among-island convergence. We developed an Ornstein-Uhlenbeck method for detecting convergence of lineages to the same peaks on a shared macroevolutionary landscape, without requiring prior hypotheses about which lineages may have converged. This allows us to test for convergence in faunas with some non-convergent species, which must be ignored by alternative methods. Applying this method to island anoles, we found exceptional clade-wide convergence among islands, supporting the hypothesis that evolutionary radiation has deterministically produced similar outcomes in Anolis. Although not every species of Greater Antillean anole has a phenotypic match from another island, most do, and among-island convergence greatly exceeds expectations from evolutionary null models. Our results demonstrate that historical contingencies are insufficient to preclude the emergence of deterministic macroevolutionary patterns during diversification.