title: Living together but remaining apart: Atlantic and Mediterranean loggerhead sea turtles (Caretta caretta) in shared feeding grounds.
abstract: Juvenile loggerhead sea turtles (Caretta caretta) from Atlantic nesting populations migrate into the western Mediterranean, where they share feeding grounds with turtles originating in the Mediterranean. In this scenario, male-mediated gene flow may lead to the homogenization of these distant populations. To test this hypothesis, we genotyped 7 microsatellites from 56 Atlantic individuals sampled from feeding grounds in the western Mediterranean and then compared the observed allele frequencies with published data of 112 individuals from Mediterranean nesting beaches. Mediterranean populations were found to be genetically differentiated from the Atlantic stock reaching the western Mediterranean (F(st) = 0.029, P < 0.001); therefore, the possible mating events between Atlantic and Mediterranean individuals are not sufficient to homogenize these 2 areas. The differentiation observed between these 2 areas demonstrates that microsatellites are sufficiently powerful for mixed stock analysis and that individual assignment (IA) tests can be performed in combination with mitochondrial DNA (mtDNA) analysis. In a set of 197 individuals sampled in western Mediterranean feeding grounds, 87% were robustly assigned to Atlantic or Mediterranean groups with the combined marker, as compared with only 52% with mtDNA alone. These findings provide a new approach for tracking the movements of these oceanic migrants and have strong implications for the conservation of the species.
authors.affiliation: Department of Animal Biology, Faculty of Biology, University of Barcelona, Avda Diagonal 645, E-08028 Barcelona, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Carreras
authors.forename: Marta
authors.initials: M
authors.lastname: Pascual
authors.forename: Luis
authors.initials: L
authors.lastname: Cardona
authors.forename: Adolfo
authors.initials: A
authors.lastname: Marco
authors.forename: Juan Jesús
authors.initials: JJ
authors.lastname: Bellido
authors.forename: Juan José
authors.initials: JJ
authors.lastname: Castillo
authors.forename: Jesús
authors.initials: J
authors.lastname: Tomás
authors.forename: Juan Antonio
authors.initials: JA
authors.lastname: Raga
authors.forename: Manuel
authors.initials: M
authors.lastname: Sanfélix
authors.forename: Gloria
authors.initials: G
authors.lastname: Fernández
authors.forename: Alex
authors.initials: A
authors.lastname: Aguilar
mesh_terms: D025041:Animal Migration; D000818:Animals; D001267:Atlantic Ocean; D004272:DNA, Mitochondrial / Q000235:genetics*; D005247:Feeding Behavior / Q000502:physiology; D005260:Female; D051456:Gene Flow; D014644:Genetic Variation; D005828:Genetics, Population / Q000379:methods*; D006239:Haplotypes; D008297:Male; D008522:Mediterranean Sea; D018895:Microsatellite Repeats; D008928:Mitochondria / Q000235:genetics; D058974:Phylogeography; D012098:Reproduction / Q000235:genetics*; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D014426:Turtles / Q000235:genetics*
chemical_list: D004272:DNA, Mitochondrial