title: Phylogeography, phylogeny and hybridization in trichechid sirenians: implications for manatee conservation.
abstract: Abstract The three living species of manatees, West Indian (Trichechus manatus), Amazonian (Trichechus inunguis) and West African (Trichechus senegalensis), are distributed across the shallow tropical and subtropical waters of America and the western coast of Africa. We have sequenced the mitochondrial DNA control region in 330 Trichechus to compare their phylogeographic patterns. In T. manatus we observed a marked population structure with the identification of three haplotype clusters showing a distinct spatial distribution. A geographic barrier represented by the continuity of the Lesser Antilles to Trinidad Island, near the mouth of the Orinoco River in Venezuela, appears to have restricted the gene flow historically in T. manatus. However, for T. inunguis we observed a single expanding population cluster, with a high diversity of very closely related haplotypes. A marked geographic population structure is likely present in T. senegalensis with at least two distinct clusters. Phylogenetic analyses with the mtDNA cytochrome b gene suggest a clade of the marine Trichechus species, with T. inunguis as the most basal trichechid. This is in agreement with previous morphological analyses. Mitochondrial DNA, autosomal microsatellites and cytogenetic analyses revealed the presence of hybrids between the T. manatus and T. inunguis species at the mouth of the Amazon River in Brazil, extending to the Guyanas and probably as far as the mouth of the Orinoco River. Future conservation strategies should consider the distinct population structure of manatee species, as well as the historical barriers to gene flow and the likely occurrence of interspecific hybridization.
authors.affiliation: Laboratory of Biodiversity and Molecular Evolution (LBEM), Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
authors.forename: Juliana A
authors.initials: JA
authors.lastname: Vianna
authors.forename: Robert K
authors.initials: RK
authors.lastname: Bonde
authors.forename: Susana
authors.initials: S
authors.lastname: Caballero
authors.forename: Juan Pablo
authors.initials: JP
authors.lastname: Giraldo
authors.forename: Régis P
authors.initials: RP
authors.lastname: Lima
authors.forename: Annmarie
authors.initials: A
authors.lastname: Clark
authors.forename: Míriam
authors.initials: M
authors.lastname: Marmontel
authors.forename: Benjamín
authors.initials: B
authors.lastname: Morales-Vela
authors.forename: Maria José
authors.initials: MJ
authors.lastname: De Souza
authors.forename: Leslee
authors.initials: L
authors.lastname: Parr
authors.forename: Marta A
authors.initials: MA
authors.lastname: Rodríguez-Lopez
authors.forename: Antonio A
authors.initials: AA
authors.lastname: Mignucci-Giannoni
authors.forename: James A
authors.initials: JA
authors.lastname: Powell
authors.forename: Fabrício R
authors.initials: FR
authors.lastname: Santos
mesh_terms: D000818:Animals; D003247:Conservation of Natural Resources; D004272:DNA, Mitochondrial; D014644:Genetic Variation; D005828:Genetics, Population; D006824:Hybridization, Genetic; D018895:Microsatellite Repeats; D010802:Phylogeny; D013045:Species Specificity; D020455:Trichechus / Q000235:genetics*
chemical_list: D004272:DNA, Mitochondrial