Older than the islands: origin and diversification of Galápagos leaf-toed geckos (Phyllodactylidae: Phyllodactylus) by multiple colonizations.

Abstract

We re-examine the biogeography of the leaf-toed geckos (Phyllodactylus) endemic to the Gala Ìpagos Islands. Our aim was to (1) test the multiple-colonization hypothesis against the single-colonization scenario proposed for most terrestrial organisms in the archipelago, (2) estimate the age of colonization of Phyllodactylus, and (3) evaluate the roles of dispersal and vicariance in the evo- lution of these lizards. Phylogenetic relationships were evaluated with maximum-likelihood and Bayesian methods, including the estimation of divergence times and species trees. Previous biogeographical hypotheses were evaluated with tree-topology tests. Our results support a multiple-colonization scenario: all but one spe- cies of Phyllodactylus in the Gala Ìpagos Islands belonged to a single radiation. The founders of this radiation colonized the archipelago 13.2 Ma when the islands currently above water had not yet emerged. Ten million years later, the ancestors of Phyllodactylus darwini colonized San Cristo Ì bal. As with other Gala Ìpagos organisms, the Pacific coast of South America seems to have been the source for the founders that led to the oldest radiation of leaf-toed geckos. Unlike most Gala Ìpagos endemics, however, P. darwini might have originated in the Andes. Our phylogenetic hypotheses and recent palaeogeographical data support both dispersal and vicariance as mechanisms leading to the radiation of leaf-toed geckos in the Gala Ìpagos Islands.