Dhami K.K., Zhuravlev Yu.N., Peters J.L.
В журнале International Journal of Avian & Wildlife Biology
Год: 2018 Том: 3 Номер: 3 Страницы: 186-197
Heterogeneity in genetic diversity and differentiation is a reflection of various past demographic events and evolutionary forces (Gene flow, divergence, Bottlenecks, mutations, selection etc.) that may have shaped the existing DNA polymorphisms in the genetic data. The gadwall (Anas strepera) is a waterfowl species that has a holoarctic distribution across North America (New World) and Eurasia (Old World), while the Asian Falcated duck (A. falcata) has a restricted distribution across Eastern Asia, where the two species share their breeding ranges. Previous studies revealed a strong structure between the Old World and New World gadwall populations and a high among locus heterogeneity in the genetic diversity. In this study, we assessed the rates of introgression between the falcated duck and gadwall populations under three coalescent models of introgression using a genomic transect of non–coding DNA. We sampled nineteen nuclear introns that mapped to nineteen different chromosomes and evaluated all three population isolation–with migration models of coalescent history between the gadwalls and falcated ducks. The results revealed introgression from falcated duck population into NW gadwall population, but not into OW gadwall population or from any gadwall population into Asian falcated duck population. The nucleotide diversity in the falcated duck varied over 100–fold among the nineteen loci, however the genetic differentiation varied more than 20 fold among the sequenced loci. Using this comprehensive dataset, we conclude that hybridization alone is insufficient to explain the observed among–locus heterogeneity in genetic diversity in the non–coding DNA of both waterfowl species suggesting a prominent role of selection.
