title: Reproductive synchrony in a recovering bottlenecked sea turtle population.
abstract: 1. The assessment of species extinction risk has been well established for some time now. Assessing the potential for recovery in endangered species is however much more challenging, because complementary approaches are required to detect reliable signals of positive trends. 2. This study combines genetics, demography and behavioural data at three different time-scales to assess historical and recent population changes and evidence of reproductive synchrony in a small population of olive ridley sea turtle Lepidochelys olivacea. Lepidochelys is considered as the most extraordinary example of reproductive synchrony in reptiles, yet to date, it has only been reported in large populations. 3. Using Bayesian coalescent-based models on microsatellite nuclear DNA variability, we demonstrate that effective population size in olive ridleys nesting in French Guiana has dramatically declined by 99% over the last 20 centuries. This low current population size is further illustrated by the absence of genetic mitochondrial DNA diversity in the present nesting population. Yet, monitoring of nesting sites in French Guiana suggests a possible recovery of the population over the last decade. 4. Satellite telemetry shows that over the first 14 days of their 28-days inter-nesting interval, i.e. when eggs maturation is likely to occur, gravid females disperse over the continental shelf. They then gather together with a striking spatiotemporal consistency close to the nesting site, where they later emerge for their second nesting event. 5. Our results therefore suggest that reproductive synchrony also occurs in small populations. Olive ridleys may ensure this synchrony by adjusting the duration of the second half of their inter-nesting interval prior to landing, possibly through social mediation. 6. Such reproductive synchrony may be related to the maintenance of some species-specific strategy despite former collapse and may contribute to the present population recovery. The gregarious behaviour of reproductive individuals close to shore where human-induced perturbations occur is however a cause for conservation concern for this still poorly known species.
authors: Université de Strasbourg, IPHC, 23 rue Becquerel, 67087 Strasbourg, France.
authors: Virginie
authors: V
authors: Plot
authors: Benoît
authors: B
authors: de Thoisy
authors: Stéphane
authors: S
authors: Blanc
authors: Laurent
authors: L
authors: Kelle
authors: Anne
authors: A
authors: Lavergne
authors: Hélène
authors: H
authors: Roger-Bérubet
authors: Yann
authors: Y
authors: Tremblay
authors: Sabrina
authors: S
authors: Fossette
authors: Jean-Yves
authors: JY
authors: Georges
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D002467:Cell Nucleus / Q000235:genetics; D045303:Cytochromes b / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics; D005260:Female; D005616:French Guiana; D014644:Genetic Variation; D018895:Microsatellite Repeats; D008969:Molecular Sequence Data; D009068:Movement; D009425:Nesting Behavior; D011157:Population Dynamics; D058998:Remote Sensing Technology; D014426:Turtles / Q000235:genetics / Q000502:physiology*
chemical_list: D004272:DNA, Mitochondrial; D045303:Cytochromes b