5 research outputs found
PrĂncipe island hawksbills: Genetic isolation of an eastern Atlantic stock
The hawksbill turtle is a critically endangered species that has been extensively exploited for centuries. PrĂncipe Island off western Africa harbours one of the species' major nesting populations in the eastern Atlantic, as well as hosting year-round foraging aggregations of juveniles, subadults and adult males. To gain insight into the population's genetic structure and relationships with regional stocks, we analysed mitochondrial DNA (mtDNA) sequences of nesting females (N = 9), foraging adult females (N = 11), adult males (N = 32), subadults (N = 15) and juveniles (N = 80). The nesting population was found to be ïŹxed for a single haplotype (EATL), which had been previously reported in both western and eastern Atlantic hawksbill foraging sites but had no known rookery source prior to this study. Thus it is now possible to conïŹrm the westward transoceanic movement by hawksbills originating from PrĂncipe Island. Our analyses demonstrated that the PrĂncipe Island nesting colony is genetically distinct from breeding populations in the western Atlantic and is phylogenetically linked with Indo-PaciïŹc hawksbill clades, suggesting that PrĂncipe Island was most likely colonised by migrants from the Indian Ocean via the Cape of Good Hope in southern Africa. Mixed stock analyses revealed that the eastern Atlantic appears to be the primary foraging area for PrĂncipe hawksbills (75%) while most of the foraging juveniles in PrĂncipe waters originate from the PrĂncipe rookery (84%). Furthermore, the presence of Caribbean haplotypes at low frequencies (b 5%) suggests that eastward transatlantic movements by juveniles to distant foraging and developmental habitats also take place. Depleted hawksbill populations in the eastern Atlantic combined with the low genetic variability and high genetic distinctiveness found in the PrĂncipe nesting and foraging aggregations with respect to the western Atlantic, underscore the high degree of isolation and vulnerability of this eastern Atlantic stock. These characteristics are highly relevant for the development of effective conservation programmes and highlight the urgent need to consolidate international cooperation across regional boundariesPeer reviewe