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Connectivity, population structure, and conservation of Ecuadorian green sea turtles

Abstract:

Studies of highly migratory species that increase our understanding of the dynamicsof genetic diversity, migratory routes, and genetic connectivity are essential for informing conservationactions. Genetic data for green turtles Chelonia mydas from Ecuador have only been availablefrom Galápagos Islands (GPS) rookeries, but not from foraging aggregations. Furthermore,green turtles from habitats associated with mainland Ecuador (Machalilla National Park; MNP)have not been sampled. To assess the genetic relationships between nesting and foraging aggregationsfrom these 2 regions and other regional populations, the mitochondrial DNA (mtDNA)control region was sequenced from 133 turtles. Conventional FST (haplotype frequency) and φST(sequence-based) values were low and non-significant between Ecuadorian rookeries, suggestinghigh connectivity between these sites located ca. 1000 km apart. Mixed stock analysis (MSA) indicateda dominant (>94%) GPS-MNP contribution to both foraging grounds, with small and nearlynegligible contributions from other rookeries in the region (e.g. Costa Rica and Mexico). Whileorphan haplotypes were not included in the MSA because their rookery of origin is not known,their close genetic relationships to Western and Central Pacific mtDNA clades suggests that a relativelylarge percentage of turtles at the combined foraging sites (>10%) have been involved intransoceanic migration events. The genetic links between GPS and MNP C. mydas nesting populationsrevealed by our study highlight the need to incorporate the nesting populations fromcoastal Ecuador in more comprehensive future conservation planning.