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Biogeography and Divergence in Guaiacum sanctum (Zygophyllaceae) Revealed in Chloroplast DNA: Implications for Conservation in the Florida Keys
- Dertien, Joseph R., Duvall, Melvin R.
- Biotropica 2009 v.41 no.1 pp. 120-127
- Convention on International Trade in Endangered Species, Guaiacum sanctum, biogeography, chloroplast DNA, gene flow, genetic variation, habitat fragmentation, indigenous species, parasites, phylogeny, population ecology, trees, tropics, Caribbean, Florida, Mexico
- Guaiacum sanctum (lignumvitae, guayacán) comprises economically important and globally endangered trees endemic to the dry neotropics. These trees were historically over-harvested and now G. sanctum is among the species listed by IUCN and CITES. Guaiacum sanctum was once found throughout the Florida Keys, but anthropogenic habitat fragmentation and exploitation have left only one significant population, on Lignumvitae Key. The ecology of this population is additionally subject to hurricane-mediated effects and an endemic parasite. Genetic profiles were determined for the Lignumvitae and putative source populations of G. sanctum to assess variability and to test biogeographic hypotheses. These data were analyzed by phylogenetic and statistical parsimony analyses. The results were most readily interpreted as indicating historical fragmentation followed by long-term isolation. However, recent dispersal or gene flow could not be entirely excluded. Both types of analyses strongly support a significant genetic divergence between Caribbean and Mexican populations of G. sanctum and also suggest bidirectional dispersal of G. sanctum into Lignumvitae Key from both the Caribbean and Mexico. These results inform the process of restoring G. sanctum in the Keys.