Comparison of the genetics and nesting ecology of two green turtle rookeries

Abstract

AbstractWe characterize the behavioral, phenotypic and genotypic characteristics of the two main green turtle Chelonia mydas nesting populations remaining in Taiwan and examine how the differing ecology of the nesting environments on each island may have influenced these life‐history traits. Wan‐an Island in the south‐west sector of the Taiwan Straits was found to be hotter and drier than Lanyu Island located south‐east of Taiwan in the Pacific Ocean. The frequency of nesting attempts and the internesting intervals were both significantly greater (mean nesting attempts: 15.4 vs. 15.2, mean internesting interval: 13.7 vs. 10.6 days) for the Wan‐an nesters. Nests were deeper (69.6 vs. 69.0 cm) while the incubation duration was shorter on this island (52.1 vs. 54.7 days). Green turtles were larger on Lanyu, but deposited smaller eggs. Nests on Lanyu had higher hatching success, hatchling emergence success and clutch survival rate (hatching success; 72.2 vs. 80.76%, hatchling emergence success; 47 vs. 64.1%, clutch survival rate; 67.7 vs. 70.3%). However, hatchlings on Wan‐an were larger (HC; 47.6 vs. 46.6 cm. HW; 23.9 vs. 21.7 cm). Analysis of mitochondrial DNA sequences obtained from a total of 53 nesters indicated that both rookeries are genetically distinct (FST=0.673, P<0.00001), with a single haplotype characterizing the Lanyu rookery (n=13). This lack of gene flow between the two rookeries is evidence for localized natal homing and is consistent with the morphological and behavioral differences that we detected between the two rookeries. These findings are surprising given the close geographic proximity of the two rookeries.