title: Re-examination of population structure and phylogeography of hawksbill turtles in the wider Caribbean using longer mtDNA sequences.
abstract: Management of the critically endangered hawksbill turtle in the Wider Caribbean (WC) has been hampered by knowledge gaps regarding stock structure. We carried out a comprehensive stock structure re-assessment of 11 WC hawksbill rookeries using longer mtDNA sequences, larger sample sizes (N = 647), and additional rookeries compared to previous surveys. Additional variation detected by 740 bp sequences between populations allowed us to differentiate populations such as Barbados-Windward and Guadeloupe (F (st) = 0.683, P < 0.05) that appeared genetically indistinguishable based on shorter 380 bp sequences. POWSIM analysis showed that longer sequences improved power to detect population structure and that when N < 30, increasing the variation detected was as effective in increasing power as increasing sample size. Geographic patterns of genetic variation suggest a model of periodic long-distance colonization coupled with region-wide dispersal and subsequent secondary contact within the WC. Mismatch analysis results for individual clades suggest a general population expansion in the WC following a historic bottleneck about 100 000-300 000 years ago. We estimated an effective female population size (N (ef)) of 6000-9000 for the WC, similar to the current estimated numbers of breeding females, highlighting the importance of these regional rookeries to maintaining genetic diversity in hawksbills. Our results provide a basis for standardizing future work to 740 bp sequence reads and establish a more complete baseline for determining stock boundaries in this migratory marine species. Finally, our findings illustrate the value of maintaining an archive of specimens for re-analysis as new markers become available.
authors.affiliation: Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration,  La Jolla, CA, USA.
authors.forename: Robin A
authors.initials: RA
authors.lastname: Leroux
authors.forename: Peter H
authors.initials: PH
authors.lastname: Dutton
authors.forename: F Alberto
authors.initials: FA
authors.lastname: Abreu-Grobois
authors.forename: Cynthia J
authors.initials: CJ
authors.lastname: Lagueux
authors.forename: Cathi L
authors.initials: CL
authors.lastname: Campbell
authors.forename: Eric
authors.initials: E
authors.lastname: Delcroix
authors.forename: Johan
authors.initials: J
authors.lastname: Chevalier
authors.forename: Julia A
authors.initials: JA
authors.lastname: Horrocks
authors.forename: Zandy
authors.initials: Z
authors.lastname: Hillis-Starr
authors.forename: Sebastian
authors.initials: S
authors.lastname: Troëng
authors.forename: Emma
authors.initials: E
authors.lastname: Harrison
authors.forename: Seth
authors.initials: S
authors.lastname: Stapleton
mesh_terms: D000818:Animals; D001460:Barbados; D017691:Caribbean Region; D004272:DNA, Mitochondrial; D056727:Endangered Species; D005260:Female; D014644:Genetic Variation; D005828:Genetics, Population; D019430:Guadeloupe; D006239:Haplotypes; D008957:Models, Genetic; D010802:Phylogeny; D058974:Phylogeography; D011110:Polymorphism, Genetic; D011156:Population Density; D014426:Turtles / Q000235:genetics*
chemical_list: D004272:DNA, Mitochondrial