Research Interests: Exostema and evolution in the Rubiaceae

I study the taxonomy (scientific naming and classification) and phylogeny (evolutionary relationships) of Exostema and of related groups in the Coffee-Quinine family (Rubiaceae). Exostema is a remarkably diverse genus of 25 species of shrubs and trees which grow in tropical/subtropical regions of the Americas, mostly on the islands of Cuba and Hispaniola. I'm especially interested in the pollination biology of these species (bees, butterflys and moths are involved), their biogeography (migrations from South America to the West Indies over tens of millions of years colonized the islands), speciation (why are so many species in Cuba, the Dominican Republic and Haiti?), and ecological specializations (how did this group evolve from large rainforest trees into spiney desert shrubs and long-flowered river-bed plants?). I use morphological and DNA data to investigate phylogenetic relationships. My taxonomic research involves study of herbarium material (dried pressed plant specimens) and the historical record (literature) for these species. I do field work in the Caribbean region to collect and study the plants and their ecology in the wild. Exostema also included many medicinal plant species, which are effective against the malaria parasite Plasmodium falciparum, according to modern and historical reports.