North Carolina, USA, represents the southern extent of the American black duck's (Anas rubripes) breeding range. Mallards (A. platyrhynchos) are present on the breeding grounds of the American black duck and hybridization is observed between these species; therefore, we assessed the genetic integrity, hybridization rates, and population structure of this local breeding population. We extracted genomic and mitochondrial DNA from chorioallantoic membranes and contour feathers from monitored black duck nests. We then prepared the extracted DNA for analysis using high-throughput DNA sequencing methods (ddRAD-seq). First, we assessed nuclear and mitochondrial population structure, genetic diversity, and differentiation across samples from North Carolina, and compared them against 199 genetically vetted mallards, black ducks, and mallard × black duck hybrids that served as genetic references. Next, we tested for parentage and sibling relationship and overall relatedness of black ducks in North Carolina. We recovered strong population structure and high co-ancestry across genetic markers due to interrelatedness among sampled nests in North Carolina and concluded that black ducks have been locally breeding in this area for a prolonged period of time. Despite a high level of interrelatedness among our samples, nucleotide diversity was similar to the reference continental black duck population, suggesting little effect of genetic drift, including inbreeding. Additionally, we conclude that molecular diversity of black ducks in North Carolina is maintained at reference population levels through the influx of genetic material from unrelated, migrating male black ducks. Finally, we report a hybridization level of 47.5%, covering 3 filial generations. Of identified hybrids, 54.7% and 53% were the direct result of interbreeding between black ducks and captive-reared or wild mallards, respectively. We conclude that because of high rates of interspecific hybridization and successive backcrossing events, introgression from wild and feral mallards is occurring into this population of breeding black ducks and requires careful consideration in future management efforts. © 2021 The Wildlife Society.

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北卡罗来纳州野鸭-黑鸭杂交和种群遗传结构

美国北卡罗来纳州代表美国黑鸭 ( Anas rubripes ) 繁殖范围的南部范围。野鸭（A. platyrhynchos) 存在于美国黑鸭的繁殖地，并且在这些物种之间观察到杂交；因此，我们评估了当地繁殖种群的遗传完整性、杂交率和种群结构。我们从受监测的黑鸭巢的绒毛膜尿囊膜和轮廓羽毛中提取了基因组和线粒体 DNA。然后我们准备提取的 DNA 用于使用高通量 DNA 测序方法 (ddRAD-seq) 进行分析。首先，我们评估了北卡罗来纳州样本的核和线粒体种群结构、遗传多样性和分化，并将它们与 199 只经过基因审查的野鸭、黑鸭和野鸭×黑鸭杂种作为遗传参考进行比较。下一个，我们测试了北卡罗来纳州黑鸭的亲子关系和兄弟姐妹关系以及整体相关性。由于北卡罗来纳州采样巢穴之间的相关性，我们恢复了强大的种群结构和跨遗传标记的高共同祖先，并得出结论，黑鸭已在该地区本地繁殖了很长时间。尽管我们的样本之间存在高度相关性，但核苷酸多样性与参考大陆黑鸭种群相似，表明遗传漂变的影响很小，包括近交。此外，我们得出结论，北卡罗来纳州黑鸭的分子多样性通过来自无关的迁徙雄性黑鸭的遗传物质的流入而保持在参考种群水平。最后，我们报告了 47.5% 的杂交水平，涵盖3代。在确定的杂交种中，分别有 54.7% 和 53% 是黑鸭与人工饲养或野生野鸭之间杂交的直接结果。我们得出的结论是，由于种间杂交率高和连续回交事件，野生和野鸭的基因渗入正在这个繁殖黑鸭种群中发生，需要在未来的管理工作中仔细考虑。© 2021 野生动物协会。野生和野鸭的基因渗入正在繁殖黑鸭种群中，需要在未来的管理工作中仔细考虑。© 2021 野生动物协会。野生和野鸭的基因渗入正在繁殖黑鸭种群中，需要在未来的管理工作中仔细考虑。© 2021 野生动物协会。