Abstract

Anolis lizards in the West Indies are one of the best-studied examples of adaptive radiation. Speciation and diversification in the Caribbean islands have led to the present recognition of hundreds of anole species. Anoles have evolved independently on many of these islands, particularly on the Greater Antillean islands, including Cuba. The Cuban anoles evolved in situ, yet have since spread to other regions, including the Bahamas, the Cayman Islands, and the Cay Sal Bank. The Cay Sal Bank encompasses a small ring of islands located between Florida, USA and Cuba, and is politically part of the Bahamas. Within these originally Cuban Anolis lineages, two species occur on Cay Sal Bank: the brown anole, Anolis sagrei, and the green anole, Anolis fairchildi. It is unknown whether these two anole species arrived to Cay Sal Bank from Cuba to the south or the Bahamas to the east. Additionally, it is not clear whether Anolis fairchildi, a Cay Sal endemic, is a valid species. On the island of Grand Cayman, an unidentified species of green anole has recently been introduced. The same question applies as to where this species originated and to what species it belongs. To examine all of these alternatives, genetic data was generated for the mitochondrial locus ND2 from A. fairchildi, A. sagrei, three unknown samples from Grand Cayman, and related green and brown anole species. The resulting sequences were aligned with data from other West Indian anoles and a series of phylogenetic trees was constructed to examine these relationships. The divergence times were estimated for these species using calibrated molecular clock analyses in the program BEAST. The data suggest that both A. fairchildi and A. sagrei colonized Cay Sal Bank from western Cuba, not the Bahamas, during the mid-to-late Pleistocene. Based on phylogenetic relationships of the Cuban anoles, A. fairchildi is not a valid species, and has recently diverged and formed a small clade within the larger Cuban A. porcatus group. Using forensic phylogenetics, the three Grand Cayman green anole sequences identified as Cuban A. porcatus. One of these sequences is sister to the western Cuba A. porcatus and the other two are sister to the introduced Dominican Republic A. porcatus, clouding the likely origins of the population. Future work might include additional sampling of introduced A. porcatus.

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