Delineation of population structure provides valuable information for conservation and management of species, as levels of demographic and genetic connectivity not only affect population dynamics but also have important implications for adaptability and resiliency of populations and species. Here, we measure population genetic structure and connectivity across the ranges of two sister species of sea ducks: Barrow's goldeneye Bucephala islandica and common goldeneye B. clangula. We use two different marker types: 7–8 nuclear microsatellite loci assayed across 229 samples and 3678 double digest restriction‐site associated DNA sequencing (ddRAD‐seq) loci assayed across 61 samples. First, both datasets found no evidence of genetic structure within common or Barrow's goldeneye, including between North American and European samples of common goldeneye. These results are in contrast with previous mitochondrial DNA, band recovery and telemetry data which suggest that goldeneyes are structured across their range. We posit that the discordance between autosomal genetic markers and other data types suggests that males, possibly subadult males, may be maintaining genetic connectivity across each species' respective ranges. Next, although mate choice consequences resulting from inter‐specific brood parasitism was hypothesized to cause some level of gene flow between goldeneye species, we only identified a single F1 hybrid with no further evidence of contemporary or historical gene flow. Despite ddRAD‐seq demographic analyses which recovered an optimum evolutionary model of split‐with‐migration (i.e. secondary contact), estimates of gene flow were <<1 migrant per generation in both directions. Together, we conclude that either strong ecological barriers or assortative mating are likely playing a role in preventing further backcrossing. Finally, demographic analyses estimated a relatively deep divergence time between Barrow's goldeneye and common goldeneye of ~1.6 million years before present and suggests that the genomes of both species have been under similar evolutionary constraints.

中文翻译：

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高位点保真度不等于北美常见白点和巴罗白点的种群遗传结构

人口结构的划分为物种的保护和管理提供了宝贵的信息，因为人口统计和遗传连通性的水平不仅影响种群动态，而且对种群和物种的适应性和适应力也具有重要意义。在此，我们测量了两种姐妹海鸭的种群遗传结构和连通性：Barrow的金眼Bucephala islandica和常见的金眼B. clangula。我们使用两种不同的标记类型：在229个样品中测定的7-8个核微卫星基因座和在61个样品中测定的3678个双酶切限制性位点相关的DNA测序（ddRAD-seq）基因座。首先，两个数据集都没有发现普通或巴罗黄金眼内的遗传结构证据，包括在北美和欧洲的普通黄金眼样本之间。这些结果与以前的线粒体DNA，谱带恢复和遥测数据形成对比，表明线眼在其整个范围内均具有结构。我们认为常染色体遗传标记与其他数据类型之间的不一致表明，雄性，可能是成年雄性，可能在每个物种各自的范围内保持遗传连通性。下一个，尽管假设种间种寄生导致的配偶选择后果导致了金眼种之间某种程度的基因流动，但我们只鉴定出一个单一的F1杂种，没有当代或历史基因流动的进一步证据。尽管ddRAD-seq人口统计学分析恢复了迁移分裂（即二次接触）的最佳进化模型，但基因流量的估计在两个方向上均是每代<< 1个移民。总之，我们得出的结论是，强大的生态屏障或分类交配都可能在防止进一步的回交中发挥作用。最后，人口统计分析估计巴罗的金眼和普通金眼之间的分歧时间相对较深，约为〜1。