Mito‐nuclear discord in six congeneric lineages of Holarctic ducks (genus Anas) |
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Authors: | Jeffrey L. Peters Kevin Winker Kendra C. Millam Philip Lavretsky Irina Kulikova Robert E. Wilson Yuri N. Zhuravlev Kevin G. McCracken |
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Affiliation: | 1. Department of Biological Sciences, Wright State University, , Dayton, OH, 45435 USA;2. University of Alaska Museum, , Fairbanks, AK, 99775 USA;3. Institute of Biology and Soil Science, Far East Branch, Russian Academy of Sciences, , Vladivostok, 690022 Russia;4. Institute of Arctic Biology, University of Alaska, Fairbanks, , Fairbanks, AK, 99775 USA;5. Department of Biology, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, , Coral Gables, FL, 33146 USA |
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Abstract: | Many species have Holarctic distributions that extend across Europe, Asia and North America. Most genetics research on these species has examined only mitochondrial (mt) DNA, which has revealed wide variance in divergence between Old World (OW) and New World (NW) populations, ranging from shallow, unstructured genealogies to deeply divergent lineages. In this study, we sequenced 20 nuclear introns to test for concordant patterns of OW–NW differentiation between mtDNA and nuclear (nu) DNA for six lineages of Holarctic ducks (genus Anas). Genetic differentiation for both marker types varied widely among these lineages (idiosyncratic population histories), but mtDNA and nuDNA divergence within lineages was not significantly correlated. Moreover, compared with the association between mtDNA and nuDNA divergence observed among different species, OW–NW nuDNA differentiation was generally lower than mtDNA divergence, at least for lineages with deeply divergent mtDNA. Furthermore, coalescent estimates indicated significantly higher rates of gene flow for nuDNA than mtDNA for four of the six lineages. Thus, Holarctic ducks show prominent mito‐nuclear discord between OW and NW populations, and we reject differences in sorting rates as the sole cause of the within‐species discord. Male‐mediated intercontinental gene flow is likely a leading contributor to this discord, although selection could also cause increased mtDNA divergence relative to weak nuDNA differentiation. The population genetics of these ducks contribute to growing evidence that mtDNA can be an unreliable indicator of stage of speciation and that more holistic approaches are needed for species delimitation. |
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Keywords: | Anatidae comparative phylogeography dabbling ducks genetic drift selection sex‐biased gene flow |
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