Double‐crested cormorants (Phalacrocorax auritus) recovered from a demographic bottleneck so well that they are now considered a nuisance species at breeding and wintering grounds across the United States and Canada. Management of this species could be improved by refining genetic population boundaries and assigning individuals to their natal population. Further, recent radio‐telemetry data suggest the existence of Interior and Atlantic migratory flyways, which could reduce gene flow and result in substantial genetic isolation. In this study, we used 1,784 individuals collected across the eastern United States, a large panel of microsatellite markers developed for this species, and individuals banded as chicks and recaptured as adults to explore the effects of migratory flyways on population structure, quantify the genetic effects of demographic bottlenecks, and determine whether individuals could be assigned to their natal population based on genotype. We found evidence for genetic population division only along migratory flyways, no evidence of genetic bottlenecks, and mixed effectiveness of assignment tests. Our population structure findings suggest that gene flow is high across large scales; for example, individuals from New York, Minnesota, and Alabama are all in panmixia. We also found that traditional subspecies ranges may not be valid because >1 subspecies was present in single genetic populations. The lack of evidence for genetic bottlenecks also likely underscores the vagility of this species, suggesting that even during demographic bottlenecks, populations were not isolated from allelic exchange. Finally, the failure of assignment tests to consistently perform is likely due in part to imperfect a priori sampling of Atlantic and Interior chicks and the high vagility of adults. We conclude that the demographic bottleneck is not likely to have reduced genetic diversity, and that assignment tests remain unreliable for this species. We recommend double‐crested cormorants be managed by flyway. Further development of genomic resources in this species could improve population subdivision resolution, improve assignment tests, and reveal further information on demographic histories. © 2020 The Wildlife Society.

中文翻译：

---

候鸟迁徙可能会影响双冠Cor的种群结构。

双冠cor（Ph））从人口瓶颈中恢复得如此之好，以至于它们现在在美国和加拿大的繁殖和越冬地被视为令人讨厌的物种。可以通过完善遗传种群边界并将个体分配给其出生种群来改善对该物种的管理。此外，最新的无线电遥测数据表明存在内陆和大西洋迁徙飞行路线，这可能会减少基因流量并导致实质性的基因隔离。在这项研究中，我们使用了在美国东部收集的1,784个个体，为该物种开发的一大批微卫星标记，以及以小鸡带状并重新捕获为成年的个体来研究迁徙迁徙对种群结构的影响，量化遗传效应人口瓶颈 并根据基因型确定是否可以将其分配给他们的出生人口。我们发现仅沿迁徙飞行路线进行遗传种群划分的证据，没有发现遗传瓶颈的证据，并且分配测试的效果不一。我们的种群结构发现表明，大规模的基因流动很高。例如，来自纽约，明尼苏达州和阿拉巴马州的人们都患有大猩猩。我们还发现传统的亚种范围可能无效，因为单个遗传种群中存在> 1个亚种。缺乏遗传瓶颈的证据也可能强调了该物种的易变性，这表明即使在人口统计学瓶颈期间，种群也不是从等位基因交换中分离出来的。最后，先验取样的大西洋和内陆小鸡以及成年后的高易变性 我们得出的结论是，人口瓶颈不太可能降低遗传多样性，并且对该物种的赋值测试仍然不可靠。我们建议由飞路管理双冠mor。该物种的基因组资源的进一步开发可以提高种群细分的分辨率，改进分配测试，并揭示有关人口历史的更多信息。©2020野生动物协会。