title: Contrasting demographic history and gene flow patterns of two mangrove species on either side of the Central American Isthmus.
abstract: Comparative phylogeography offers a unique opportunity to understand the interplay between past environmental events and life-history traits on diversification of unrelated but co-distributed species. Here, we examined the effects of the quaternary climate fluctuations and palaeomarine currents and present-day marine currents on the extant patterns of genetic diversity in the two most conspicuous mangrove species of the Neotropics. The black (Avicennia germinans, Avicenniaceae) and the red (Rhizophora mangle, Rhizophoraceae) mangroves have similar geographic ranges but are very distantly related and show striking differences on their life-history traits. We sampled 18 Atlantic and 26 Pacific locations for A. germinans (N = 292) and R. mangle (N = 422). We performed coalescence simulations using microsatellite diversity to test for evidence of population change associated with quaternary climate fluctuations. In addition, we examined whether patterns of genetic variation were consistent with the directions of major marine (historical and present day) currents in the region. Our demographic analysis was grounded within a phylogeographic framework provided by the sequence analysis of two chloroplasts and one flanking microsatellite region in a subsample of individuals. The two mangrove species shared similar biogeographic histories including: (1) strong genetic breaks between Atlantic and Pacific ocean basins associated with the final closure of the Central American Isthmus (CAI), (2) evidence for simultaneous population declines between the mid-Pleistocene and early Holocene, (3) asymmetric historical migration with higher gene flow from the Atlantic to the Pacific oceans following the direction of the palaeomarine current, and (4) contemporary gene flow between West Africa and South America following the major Atlantic Ocean currents. Despite the remarkable differences in life-history traits of mangrove species, which should have had a strong influence on seed dispersal capability and, thus, population connectivity, we found that vicariant events, climate fluctuations and marine currents have shaped the distribution of genetic diversity in strikingly similar ways.
authors.affiliation: Smithsonian Tropical Research Institute Apartado, 0843-03092, Panama ; University of Puerto Rico - Rio Piedras Campus PO BOX 23360, San Juan, Puerto Rico, 00931-3360.
authors.forename: Ivania
authors.initials: I
authors.lastname: Cerón-Souza
authors.affiliation: Departamento de Biodiversidad y Biología Evolutiva, Museo Nacional de Ciencias Naturales, MNCN-CSIC José Gutiérrez Abascal 2, 28006, Madrid, Spain.
authors.forename: Elena G
authors.initials: EG
authors.lastname: Gonzalez
authors.affiliation: Department of Biomedicine, University of Texas One West University Blvd., Brownsville, Texas, 78520.
authors.forename: Andrea E
authors.initials: AE
authors.lastname: Schwarzbach
authors.affiliation: Department of Biological Sciences, Florida International University Miami, Florida, 33199 ; USDA-ARS-SHRS, National Germplasm Repository Miami, Florida, 33158.
authors.forename: Dayana E
authors.initials: DE
authors.lastname: Salas-Leiva
authors.affiliation: Department of Biology, University of Puerto Rico-Bayamon Parque Industrial Minillas Carr 174, Bayamón, Puerto Rico, 00959-1911.
authors.forename: Elsie
authors.initials: E
authors.lastname: Rivera-Ocasio
authors.affiliation: Departamento de Biología, Sección de Genética, Universidad del Valle AA 25360, Cali, Colombia.
authors.forename: Nelson
authors.initials: N
authors.lastname: Toro-Perea
authors.affiliation: Patricia and Phillip Frost Museum of Science, 3280 South Miami Avenue Miami, Florida.
authors.forename: Eldredge
authors.initials: E
authors.lastname: Bermingham
authors.affiliation: Smithsonian Tropical Research Institute Apartado, 0843-03092, Panama.
authors.forename: W Owen
authors.initials: WO
authors.lastname: McMillan
keywords: Avicennia germinans; Neotropics; Rhizophora mangle; bottleneck; climate change; comparative phylogeography; gene flow; last glacial maximum; mangroves; population genetic structure