Species Radiation in the Genus Columnea Endemic to Jamaica
James F. Smith
Species diversity and radiations have long aroused the curiosity of scientists, one of the most famous studies being the finches found on the Galapagos islands. The most commonly studied species radiations are on islands. On remote islands, species evolve from a single colonization event, and are endemic to the area of speciation. The Caribbean islands have a complex biogeographically history that includes close proximity and connections to continents and South America. Jamaica has never had a land connection to South America. The Neotropical genus Columnea within the family Gesneriaceae comprises 13 endemic species in Jamaica. These species are morphologically diverse, ranging from small-leaved creepers to larger-leaved pubescent epiphytes. The Jamaican species were classified in two different genera in the past implying their morphological differences was the result of at least two different origins. DNA sequence data are useful for testing phylogenetic relationships and are used in this study to test the monophyly of these endemic species. Twelve of the 13 species have been included in our analysis and a monophyletic lineage for the Jamaican species is recovered. This suggests a single ancestral introduction, likely from South America, and diversification on the island with subsequent morphological diversification convergent with other species.
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