Format: ORAL

Lucas C. Majure1, Duniel Barrios2, Yuley Encarnacin1, Alan Franck1, Peter Breslin3

1Florida Museum, University of Florida, Gainesville, Florida, U.S.A. 2Universidad de La Habana, Cuba 3University of Arizona, Tucson, U.S.A.

Cactaceae are a diverse subset (ca. 1800 spp.) of the arid flora of the Americas. Major diversity centers exist in Mexico, Andean South America and eastern Brazil. The Caribbean biodiversity hotspot, including the Bahamas, and the Greater and Lesser Antilles also houses substantial diversity of the family, especially species of seasonally dry tropical forest, with around 110 species of cacti found there. Most of those species (ca. 91) are endemic to the islands, thus providing a model system for studying island biogeography and the origins of Caribbean biodiversity. Previous work has provided insight into the possible ways in which this diversity was generated, however, no broadly sampled phylogeny is yet available to test these patterns. We generated a near comprehensive dataset of Antillean species of Cactaceae, as well as close relatives based on chloroplast genomes, to test the age and origin of Caribbean cacti. Numerous putative dispersals from the continent occurred during the late Pliocene and throughout the Pleistocene, which led to the tremendous diversity of cacti we now see in the islands. In-situ radiations were most prominent on the larger islands of Cuba and Hispaniola, and those two islands also were the most influential for the further spread of cacti across the rest of the Antilles. Cactaceae provide an intriguing piece to the puzzle for understanding Caribbean biogeography, and Pleistocene climatic events appear to have played a major role in their diversification, a pattern comparable to parts of the mainland distribution of the family.