Population genetic structure and developmental migrations of sea turtles in the Chagos Archipelago and adjacent regions inferred from mtDNA sequence variation.

Patterns of mitochondrial DNA variation were used to determine genetic relationships among hawksbill (Eretmochelys imbricata) and green turtle (Chelonia mydas) populations in the Chagos Archipelago (isolated in the Central Indian Ocean) and those in three adjacent localities: the Republic of Seychelles, the Arabian Peninsula, and western Australia. Nesting hawksbills in Seychelles and Chagos are both characterized by high frequency mtDNA variants not recorded elsewhere in the world and differ from each other by significant haplotype frequency shifts. The few nesting green turtles sampled from Chagos had haplotypes shared with green turtle populations in both the eastern and western Indian Ocean but distinct from those in the Arabian Peninsula. Populations of foraging juvenile hawksbill turtles from the Chagos and Seychelles could not be genetically differentiated from each other and their pooled mtDNA frequencies are not significantly different from either Seychelles or Chagos rookeries, but are more similar to Seychelles rookeries. Notably, none of the haplotypes observed in western Australian rookeries were detected in these foraging populations. These data indicate that Seychelles is a major source of juveniles in both Seychelles and Chagos foraging populations but the possibility of Arabian Peninsula or other unsampled stocks in the region also making significant contributions cannot be preclude. Additional samples from both hawksbill and green turtle rookeries in the Chagos are needed to elucidate these patterns.
Mortimer Jeanne , Broderick A .
turtles, Mitochondrial DNA, Biogeography, Hawksbill turtle, Eretmochelys imbricata, Green turtle, Chelonia mydas, British Indian Ocean Territory Population genetics,Denaturant gradient gel electrophoresis ( DGGE)