Divergence and gene flow in the globally distributed blue‐winged ducks |
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| Authors: | Joel T. Nelson Robert E. Wilson Kevin G. McCracken Graeme S. Cumming Leo Joseph Patrick‐Jean Guay Jeffrey L. Peters |
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| Affiliation: | 1. Dept of Biological Sciences, Wright State Univ., Dayton, OH, USA;2. U. S. Geological Survey, Alaska Science Center, Anchorage, AK, USA;3. REW, Inst. of Arctic Biology, Dept of Biology and Wildlife, and Univ. of Alaska Museum, Univ. of Alaska Fairbanks, Fairbanks, AK, USA. KGM also at: Dept of Biology and Dept of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Sciences, Univ. of Miami, Coral Gables, FL, USA;4. Percy FitzPatrick Inst., DST/NRF Centre of Excellence, Univ. of Cape Town, Rondebosch, South Africa, and ARC Centre of Excellence in Coral Reef Studies, James Cook Univ., Townsville, QLD, Australia;5. Australian National Wildlife Collection, National Research Collections Australia, CSIRO, Canberra, ACT, Australia;6. Inst. for Sustainability and Innovation, College of Engineering and Science, Victoria Univ., Melbourne, VIC, Australia |
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| Abstract: | The ability to disperse over long distances can result in a high propensity for colonizing new geographic regions, including uninhabited continents, and lead to lineage diversification via allopatric speciation. However, high vagility can also result in gene flow between otherwise allopatric populations, and in some cases, parapatric or divergence‐with‐gene‐flow models might be more applicable to widely distributed lineages. Here, we use five nuclear introns and the mitochondrial control region along with Bayesian models of isolation with migration to examine divergence, gene flow, and phylogenetic relationships within a cosmopolitan lineage comprising six species, the blue‐winged ducks (genus Anas), which inhabit all continents except Antarctica. We found two primary sub‐lineages, the globally‐distributed shoveler group and the New World blue‐winged/cinnamon teal group. The blue‐winged/cinnamon sub‐lineage is composed of sister taxa from North America and South America, and taxa with parapatric distributions are characterized by low to moderate levels of gene flow. In contrast, our data support strict allopatry for most comparisons within the shovelers. However, we found evidence of gene flow from the migratory, Holarctic northern shoveler A. clypeata and the more sedentary, African Cape shoveler A. smithii into the Australasian shoveler A. rhynchotis, although we could not reject strict allopatry. Given the diverse mechanisms of speciation within this complex, the shovelers and blue‐winged/cinnamon teals can serve as an effective model system for examining how the genome diverges under different evolutionary processes and how genetic variation is partitioned among highly dispersive taxa. |
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