Incomplete lineage sorting and introgression in the diversification of Chinese spot-billed ducks and mallards

• 来源期刊: 动物学报（英文版）
• 年，卷（期）: 2019,（5）
• 页码范围: 589-597
• 页数: 9页
• 语种: 英文
• DOI: 10.1093/cz/zoy074

摘要

Incomplete lineage sorting and introgression are 2 major and nonexclusive causes of specieslevel non-monophyly.Distinguishing between these 2 processes is notoriously difficult because they can generate similar genetic signatures.Previous studies have suggested that 2 closely related duck species,the Chinese spot-billed duck Anas zonorhyncha and the mallard A.platyrhynchos were polyphyletically intermixed.Here,we utilized a wide geographical sampling,multilocus data and a coalescent-based model to revisit this system.Our study confirms the finding that Chinese spot-billed ducks and Mallards are not monophyletic.There was no apparent interspecific differentiation across loci except those at the mitochondrial DNA (mtDNA) control region and the Z chromosome (CHD1Z).Based on an isolation-with-migration model and the geographical distribution of lineages,we suggest that both introgression and incomplete lineage sorting might contribute to the observed non-monophyly of the 2 closely related duck species.The mtDNA introgression was asymmetric,with high gene flow from Chinese spot-billed ducks to Mallards and negligible gene flow in the opposite direction.Given that the 2 duck species are phenotypically distinctive but weakly genetically differentiated,future work based on genomescale data is necessary to uncover genomic regions that are involved in divergence,and this work may provide further insights into the evolutionary histories of the 2 species and other waterfowls.