Cerón-Souza, Ivania , Bermingham, Eldredge , Feliner , Gonzalo Nieto .
The intricate history of the red mangrove hybrid complex (Rhizophora mangle and Rhizophora racemosa) in the Neotropics.
Our previous work uncovered ancient hybridization and introgression between the two species of red mangrove (Rhizophora mangle and R. racemosa) that occur in the New World. This was based on a pattern detected consisting on geographically-based lineages (both for plastid and nuclear sequence data) each containing samples of both species, so that specimens of R. mangle from the Pacific were closer to R. racemosa from that ocean than to their conspecifics from the Atlantic. Ongoing hybridization in sites where the two species are sympatric was also detected based on microsatellite data. Hybridization among mangrove species (e.g., Bruguiera) and even within Rhizophora is well known particularly in the Indo-Pacific region but there, unlike the neotropical Rhizophora complex, the F1 hybrids are infertile. The ancient and ongoing introgressive hybridization pattern of the red mangrove complex in the New World makes this system particularly challenging and suggest a number of questions that imply alternative historical scenarios not all compatible with the current taxonomic arrangement. Here are some of those questions. What is the role of the final closure of Central American Isthmus (CAI) in the tempo of ancient hybridization events between the two species? Can this system contribute independent data to the geological debate on the dating of the final closure of CAI? Why R. racemosa does not occur allopatrically in the Neotropics and what is the bearing of this pattern on the origin and structure of the hybrid zones occurring between R. mangle and R. racemosa? How do the two species maintain their identity despite ancient and ongoing gene flow? What are the main reproductive barriers restricting hybridization between the two species? Are physiological traits responsible for the local and wide distribution patterns exhibited by the two species? What is the role of eustatic sea-level changes caused by glacial maxima in the current distribution patterns. In trying to throw light on this questions, we have undertaken a phylogenetic study based on sequence data from five regions: three plastidial (atpI-atpH, psbJ-petA, trnH-rpl2) and two nuclear (Apg1 and LAS, the latter associated to salinity tolerance) as well as an extended study based on nuclear microsatellites (10 loci).
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1 - Smithsonian Tropical Research Institute, Apartado 0843-03092, Panama, Republic of Panama
2 - Real Jardin Botanico, CSIC, Biodiversity and Evolution, Plaza de Murillo, 2, Madrid, 28014, Spain
Presentation Type: Oral Paper:Papers for Topics
Location: Franklin B/Hyatt
Date: Monday, July 9th, 2012
Time: 9:15 AM