title: Recent demographic history and present fine-scale structure in the Northwest Atlantic leatherback (Dermochelys coriacea) turtle population.
abstract: The leatherback turtle Dermochelys coriacea is the most widely distributed sea turtle species in the world. It exhibits complex life traits: female homing and migration, migrations of juveniles and males that remain poorly known, and a strong climatic influence on resources, breeding success and sex-ratio. It is consequently challenging to understand population dynamics. Leatherbacks are critically endangered, yet the group from the Northwest Atlantic is currently considered to be under lower risk than other populations while hosting some of the largest rookeries. Here, we investigated the genetic diversity and the demographic history of contrasted rookeries from this group, namely two large nesting populations in French Guiana, and a smaller one in the French West Indies. We used 10 microsatellite loci, of which four are newly isolated, and mitochondrial DNA sequences of the control region and cytochrome b. Both mitochondrial and nuclear markers revealed that the Northwest Atlantic stock of leatherbacks derives from a single ancestral origin, but show current genetic structuration at the scale of nesting sites, with the maintenance of migrants amongst rookeries. Low nuclear genetic diversities are related to founder effects that followed consequent bottlenecks during the late Pleistocene/Holocene. Most probably in response to climatic oscillations, with a possible influence of early human hunting, female effective population sizes collapsed from 2 million to 200. Evidence of founder effects and high numbers of migrants make it possible to reconsider the population dynamics of the species, formerly considered as a metapopulation model: we propose a more relaxed island model, which we expect to be a key element in the currently observed recovering of populations. Although these Northwest Atlantic rookeries should be considered as a single evolutionary unit, we stress that local conservation efforts remain necessary since each nesting site hosts part of the genetic diversity and species history.
authors.affiliation: Departamento de Biologia Geral, ICB, Universidade Federal de Minas Gerais, 31270-010, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Erica
authors.initials: E
authors.lastname: Molfetti
authors.forename: Sibelle Torres
authors.initials: ST
authors.lastname: Vilaça
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Georges
authors.forename: Virginie
authors.initials: V
authors.lastname: Plot
authors.forename: Eric
authors.initials: E
authors.lastname: Delcroix
authors.forename: Rozen
authors.initials: R
authors.lastname: Le Scao
authors.forename: Anne
authors.initials: A
authors.lastname: Lavergne
authors.forename: Sébastien
authors.initials: S
authors.lastname: Barrioz
authors.forename: Fabrício Rodrigues
authors.initials: FR
authors.lastname: dos Santos
authors.forename: Benoît
authors.initials: B
authors.lastname: de Thoisy
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001947:Breeding; D004272:DNA, Mitochondrial; D005260:Female; D005616:French Guiana; D014644:Genetic Variation; D006239:Haplotypes; D008297:Male; D018895:Microsatellite Repeats; D011156:Population Density; D011157:Population Dynamics; D014426:Turtles / Q000235:genetics*
chemical_list: D004272:DNA, Mitochondrial