Aim We investigated the evolutionary relationships and historical biogeography of two lizard species (Anolis desechensis and Anolis monensis) endemic to small oceanic islands in the eastern Caribbean Sea.
Location Desecheo, Mona and Monito Islands, in the Mona Passage, and Puerto Rico, eastern Caribbean Sea.
Methods We reconstructed the phylogenetic relationships of A. desechensis and A. monensis from DNA sequences of two mitochondrial genes using maximum likelihood, Bayesian inference and maximum parsimony methods. The ingroup included species from Puerto Rico (Anolis cooki, Anolis cristatellus), the Bahamas (Anolis scriptus), and the British Virgin Islands (Anolis ernestwilliamsi). We also constructed a median-joining mutational network to visualize relationships among the haplotypes of A. cooki and A. monensis from Mona and Monito Islands.
Results The three phylogenetic methods suggested the same pattern of relationships. Anolis desechensis nests within A. cristatellus, and is most closely related to A. cristatellus from south-western Puerto Rico. Our analyses also indicated that A. monensis is the sister species of A. cooki, an anole restricted to the south-western coast of Puerto Rico. Although they are closely related, the populations of A. monensis from Mona and Monito can be distinguished genetically.
Main conclusions The ancestors of A. desechensis and A. monensis colonized Desecheo, and Mona and Monito Islands, respectively, from localities in south-western Puerto Rico, not from places on Puerto Rico geographically closer to the islands. The ancestors of these two anoline species probably arrived on the islands via waif dispersal. Anolis eggs can survive immersion in salt water for several hours, thus flotsam could successfully have transported all developmental stages of these lizards from the source area to a new locality.