Waterfowl of the Hawaiian archipelago: A genetic evaluation of Laysan teal, Hawaiian ducks, and mallards

Background/Question/Methods

Island flora and fauna possess the highest vulnerability to anthropogenic disturbances and alien species introduction/invasion. For example, nearly 50% of the biotic diversity on the Hawaiian Islands has become extinct in the last two decades, with 70% of the remaining species being classified as endangered. The paleontological record shows that eleven species of Anatidae once occupied the archipelago, but only three of these remain, all of which are endangered. Current issues that continue to concern waterfowl conservationists include 1) habitat loss and destruction, 2) anthropogenic contact/disturbances, and 3) hybridization and introgression with captive and wild mallards (Anas platyrhynchos). Historical declines and current genetic introgressive trends continue to impede the restoration and management of the two endemic dabbling ducks: the Laysan teal (Anas laysanensis) and the Hawaiian duck (Anas wyvilliana). We sequenced six nuclear introns for 21 Laysan teal, 15 Hawaiian ducks, and 25 mallards (1) to determine the amount of genetic diversity in the island endemics relative to the widely distributed mallard, and (2) to test hypotheses about the evolutionary relationships among these taxa.

Results/Conclusions

Sequence data showed extremely low genetic variability in Laysan teal, suggesting that this species might be more prone to extinction in a changing environment. Hawaiian ducks had significantly more polymorphisms and shared more alleles with mallards. Additionally, the data showed significant genetic differentiation between the mallard and both Hawaiian and Laysan ducks, with the two island endemics being more closely related to each other. The nuclear data agree with previous studies that examined allozyme variation and morphology, but disagree with results from a study of mitochondrial DNA. The conflicting results from mitochondrial DNA may be a result of introgressive hybridization between Hawaiian ducks and mallards. Future work will include additional loci and additional species to better resolve the genetic relationships among the Hawaiian ducks and other mallard-like species.