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 740bp sequences between populations allowed us to differentiate populations such as Barbados-Windward and Guadeloupe (Fst = 0.683, P < 0.05) that appeared genetically indistinguishable based on shorter 380bp 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 100000-300000 years ago. We estimated an effective female population size (Nef) 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 740bp 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.
Bibliographical noteFunding Information:
Funding in Nicaragua was provided by the National Fish & Wildlife Foundation, National Geographic Society, National Marine Fisheries Service (Office of Protected Species), PADI Project Aware, the Marine Conservation Society, SeaWorld/ Busch Gardens Conservation Fund, United States Fish & Wildlife Service – Marine Turtle Conservation Act, and an anonymous donor. Laboratory analysis was funded by the National Marine Fisheries Service.
- Eretmochelys imbricata
- conservation genetics
- management units
- mitochondrial DNA
- sea turtle
- stock structure