Abstracts

Presented by Philip Lavretsky - Email: plavretsky@utep.edu

We reconstruct phylogenetic relationships within Tribe Mergini by sequencing ddRAD-seq markers (> 3000 loci) for 387 samples (N = 9-56 per taxon) across all North American sea ducks. Individual estimates of population ancestry recovered all major genera and expected relationships. However, a total of 14 samples were found to have mixed ancestry, which likely represent putative hybrids: Barrow’s x Common Goldeneye (N = 1), Common Eider x Harlequin duck (N = 4), King Eider x Spectacled Eider (N = 1), Long-tailed Duck x Black Scoter (N = 1), Long-tailed Duck x Bufflehead (N = 2), Bufflehead x White-winged Scoter (N = 3), and Harlequin Duck x Common Merganser (N = 2). In addition, all Long-tailed duck samples showed similar levels of shared coancestry with the main Eider clade, and all Steller’s Eider samples had equally high coancestry assignment to Long-tailed ducks and the main Eider clade. Species tree reconstruction recovered four well resolved major clades and was consistent with the mitochondrial-based phylogeny: (a) a sister relationship between Barrow’s and Common Goldeneye, and Bufflehead as the outgroup, (b) three species of Merganser, with Hooded Mergansers as the outgroup, (c) three species of Scoters in which Surf Scoters and White-Winged Scoters as sister taxa, and (d) all four species of Eider and Long-tailed Duck. Relationships among Eiders recovered a main, true Eider clade with a sister relationships among Common Eiders, Spectacled Eiders, and King Eiders, and a more distant relationship to Steller’s Eider. Moreover, in addition to the ancestry assignments, phylogenetic reconstructions provide additional evidence that the lineage leading to Steller’s Eiders likely had substantial genetic contribution from the Eider/Long-tailed Duck lineage, and may represent a species of hybrid origin.