Historical biogeography of the Antilles: Earth history and phylogenetics of endemic chiropteran taxa

Abstract

Vicariance and dispersal are the main hypotheses used to explain the distribution and diversification of taxa on both continents and islands. Research on the origin and diversification of island biotas is particularly appealing because these have inspired classical models in biogeography. This study examined competing explanations of Caribbean historical biogeography: an Oligocene land bridge between northern South America and the West Indies, and Cenozoic dispersal from South America and/or Central America. Separate and combined phylogenetic analyses were conducted using new molecular data and published morphological characters for five monophyletic bat lineages; Mormoops, Pteronotus, a clade comprising Brachyphylla, Erophylla, and Phyllonycteris, the subtribe Stenodermatina, and Natalidae. The resulting phylogenies were analyzed using event-based biogeographic methods, synthesized into hypotheses of area relationships, and used to generate estimates of divergence times at critical nodes. The phylogenies of three of the five lineages are congruent with a single range expansion onto the Caribbean, whereas Mormoops is also consistent with this result but further studies of fossil remains are necessary, and Antillean Pteronotus appears to be a product of at least two separate invasions. Continental Stenodermatina and Natalidae descended from Caribbean ancestors. The ancestral areas of all the lineages are Mexico, Central America, and northern South America. The patterns of area relationships derived from phylogenies are equivocal in their support for the land bridge hypothesis. The ages of the bat lineages appear to be too young to have used an Oligocene land bridge. Instead, lowering and rising sea levels at key transitions during the Miocene may have facilitated the spread, and subsequent isolation, of the bat lineages leading to diversification and shared biogeographic pattern. The role of the Miocene in Caribbean biogeographic history should be tested with additional phylogenies, new molecular data, as well as the fossil record. The correlation of geological history, phylogenetic patterns, and the timing of diversification in bats demonstrates congruent biogeographic patterns in the Caribbean are pervasive even among the most vagile organisms.