Colonizing the Caribbean: biogeography and evolution of livebearing fishes of the genus Limia(Poeciliidae)

AimWe investigate the origin and colonization of the West Indian endemic freshwater fish group Limia. We evaluate the leading hypotheses for the origins of West Indian life, including trans-oceanic dispersal, late Cretaceous vicariance, and the GAARlandia land bridge at the Eocene/Oligocene boundary. LocationGreater Antilles, with extensive sampling in the Dominican Republic. MethodsWe obtained DNA from wild sampling and the aquarium trade. We sequenced three mitochondrial (12S, ND2 and Cytb) and two nuclear genes (Rh, MYH6) for a combined molecular phylogenetic analysis to evaluate species relationships and the timing of divergence events between islands and the mainland. We used Bayesian and likelihood approaches to build phylogenies, a BEAST analysis to establish the timing of colonization, and R package BioGeoBEARS to perform a historical biogeographical reconstruction. ResultsRelaxed molecular clock results show that the ancestor to the West Indian clade, which includes the Limia and Hispaniolan Poecilia, diverged from a South American ancestor at the Eocene/Oligocene boundary. The basal Jamaican species, L. melanogaster, split from the rest of Limia at the Oligocene/Miocene boundary. Cuban and Cayman taxa are sister to a diverse species group from Hispaniola. Historical biogeographical reconstruction supported the GAARlandia DEC+j model as the best fitting model for colonization. Main conclusionsOur results support a colonization model for Limia that is concordant with the timing of GAARlandia and climate change during the Eocene/Oligocene boundary. Limia colonization was most likely a result of facilitated dispersal during a period of lower sea levels and shorter passage along the Aves Ridge. These results are also consistent with other recent molecular clock studies of dispersal limited cichlids, toads and frogs, indicating a growing body of support for the significance of Eocene/Oligocene climate change for the historical biogeography of West Indian life.