GENETIC DIVERSITY, CONNECTIVITY AND DEMOGRAPHIC HISTORY OF BONAIRE SEA TURTLES
with a discussion on sampling mixed aggregations for demographic inferences
Climate change is threatening sea turtles globally, and whether or not sea turtles will be able to adapt to and survive global warming may depend in part on their genetic diversity. Sea turtles have survived several past environmental changes, but these events, together with the more recent human exploitation, might have substantially decreased sea turtle genetic diversity.
In the present study, we investigated the green sea turtles of the feeding aggregation off Bonaire in the Dutch Caribbean for their genetic diversity, demographic history, and connectivity to other Caribbean and Atlantic feeding aggregations and rookeries.
We found current nucleotide diversity to be the highest among all Caribbean and Atlantic feeding aggregations and rookeries included in this study, while haplotype diversity was intermediate. The inferred demographic history showed a possible slight decline in genetic diversity during the past 6,000 years. The Bonaire feeding aggregation was significantly genetically differentiated from all but two other Caribbean and Atlantic feeding aggregations and rookeries, highlighting Bonaire’s uniqueness and the importance of its conservation.
However, since sea turtle feeding aggregations comprise sea turtles from several genetically distinct rookeries, we hypothesized that the demographic history inferred for Bonaire might not display local, but rather “imported” patterns from the main contributory rookeries.
A comparison between the Bonaire feeding aggregation’s demographic history and the main contributory rookeries’ supports this hypothesis. Hence we discuss the implications of sampling mixed (sea turtle) feeding aggregations on population demographic inferences in a wider context and propose future research, management and conservation strategies.
We additionally found that historic environmental changes (such as the Last Glacial Maximum) do not seem to have been associated with decreases in sea turtle genetic diversity in all but one main contributory rookery. This suggests that green sea turtle genetic diversity may not have been eroded strongly by past climatic events and may serve as “buffer” against at least some future changes.