title: Comparative phylogeography of black mangroves (Avicennia germinans) and red mangroves (Rhizophora mangle) in Florida: Testing the maritime discontinuity in coastal plants.
abstract: Previous studies of the comparative phylogeography of coastal and marine species in the southeastern United States revealed that phylogenetically diverse taxa share a phylogeographic break at the southern tip of Florida (the maritime discontinuity). These studies have focused nearly exclusively on animals; few coastal plant species in Florida have been analyzed phylogeographically. We investigated phylogeographic patterns of black mangroves (Avicennia germinans) and red mangroves (Rhizophora mangle), two coastal trees that occur on both coasts of the peninsula of Florida.
  
  
  
  We sampled and genotyped 150 individuals each of A. germinans and R. mangle, using eight microsatellite loci per species. We used observed and expected heterozygosity to quantify genetic diversity in each sampling location and allele frequencies to identify putative phylogeographic breaks and measure gene flow using BayesAss and Migrate-n. We tested the hypothesis that both species would exhibit a phylogeographic break at the southern tip of Florida.
  
  
  
  We did not find any significant phylogeographic breaks in either species. Rhizophora mangle exhibits greater genetic structure than A. germinans, contrary to expectations based on propagule dispersal capability. However, directional gene flow from the Gulf to the Atlantic was more pronounced in R. mangle, indicating that the Gulf Stream may affect genetic patterns in R. mangle more than in A. germinans.
  
  
  
  The high dispersal capability of these species may lead to high genetic connectivity between sampling locations and little geographic structure. We also identified several locations that, based on genetic data, should be the focus of conservation efforts.
authors.affiliation: Department of Biology, University of Florida, Gainesville, Florida 32611, USA Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611, USA hodel@ufl.edu.
authors.forename: Richard G J
authors.initials: RG
authors.lastname: Hodel
authors.affiliation: Department of Plant Biology, University of Campinas-UNICAMP, 13083-970 Campinas, São Paulo, Brazil.
authors.forename: Maria B de Souza
authors.initials: MB
authors.lastname: Cortez
authors.affiliation: Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611, USA The Genetics Institute, University of Florida, Gainesville, Florida 32610, USA.
authors.forename: Pamela S
authors.initials: PS
authors.lastname: Soltis
authors.affiliation: Department of Biology, University of Florida, Gainesville, Florida 32611, USA Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611, USA The Genetics Institute, University of Florida, Gainesville, Florida 32610, USA.
authors.forename: Douglas E
authors.initials: DE
authors.lastname: Soltis
mesh_terms: D032407:Avicennia / Q000235:genetics*; D001499:Bayes Theorem; D016000:Cluster Analysis; D017753:Ecosystem; D005431:Florida; D051456:Gene Flow; D005787:Gene Frequency / Q000235:genetics; D014644:Genetic Variation; D005843:Geography; D006579:Heterozygote; D058974:Phylogeography; D043982:Rhizophoraceae / Q000235:genetics*
keywords: coastal species; conservation; mangroves; maritime discontinuity; microsatellites; phylogeography