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Abstract
The Zamia pumila L. complex (Cycadales: Zamiaceae) is a monophyletic, diploid (2n = 16) and distinctive assemblage of cycad populations restricted to the West Indies and southeastern United States that has been treated as comprising one to nine species. Our research project seeks to simultaneously investigate patterns of microsatellite DNA and single copy nuclear gene sequence variation in the complex and apply these data to various evolutionary and biogeographic questions. The overall goal is to document the patterns of genetic variation and phylogeographic relationships across populations of the Zamia pumila complex throughout its range and attempt to understand the processes of speciation within the group. Collection and microsatellite genotyping has been completed from (1) the Bahamas: six islands, 23 populations, 797 samples; (2) Florida: 25 populations, 762 samples; (3) Puerto Rico: ten populations, 328 samples; (4) Jamaica: five populations, 176 samples; (5) Dominican Republic: nine populations, 405 samples; and (6) Cayman Islands: five populations, 131 samples. Collections on Cuba will take place in the summer and fall of 2013. Primer pairs for 32 simple sequence repeat (SSR) loci have been designed that are successfully capturing polymorphism in Zamia. Ten single copy nuclear genes have been isolated and successfully sequenced from a test panel of Zamia spp. Bayesian approaches, maximum likelihood, and the coalescent model will form the framework by which the SSR data will be analyzed. Phylogeographic analysis will be conducted with new software applications that handle gene tree heterogeneity, and a phylogeographic approach for evaluating conservation priority in the group will be evaluated. Our phylogeographic analyses will test whether the morphological forms suggested by previous taxonomic studies represent true species. The simultaneous analyses of microsatellite DNA and sequence-based data sets across the same organisms—particularly of a group that appears to inhabit the gray zone between population and species—will offer an unprecedented and multidimensional opportunity to test the convergence of genetics and phylogenetics and contribute further to our understanding of speciation.
Keywords: cycad, speciation, molecular genetic, molecular systematic, phylogeography, Caribbean hotspot, biodiversity
