Data from: Genetic analyses reveal hybridization but no hybrid swarm in one of the world's rarest birds

Abstract: Hybridization facilitated by human activities has dramatically altered the evolutionary trajectories of threatened taxa around the globe. Whereas introduced mammalian predators and widespread habitat loss and degradation clearly imperil the recovery and survival of the New Zealand endemic black stilt or kakī (Himantopus novaezelandiae), the risk associated with hybridization between this critically endangered endemic and its self-introduced congener, the pied stilt or poaka (H. himantopus leucocephalus) is less clear. Here we combine Bayesian admixture analyses of microsatellite data with mitochondrial DNA sequence data to assess the levels of hybridization and introgression between kakī and poaka. We show that birds classified as hybrids on the basis of adult plumage are indeed of hybrid origin and that hybridisation between kakī and poaka is both extensive and bidirectional. Despite this, we found almost no evidence for introgression from poaka to kakī, thus negating a popular belief that kakī represent a hybrid swarm. To our knowledge, ours represents the first comprehensive study to document a lack of widespread introgression for a species at risk despite a recent history of extensive bidirectional human-induced hybridization. We attribute this rather surprising result, in part, to reduced reproductive success in female hybrids combined with a transient male-biased kakī sex ratio. To maximize the evolutionary potential of kakī, we use these data to recommend conservation management activities aimed to maintain the genetic integrity and to maximize the genetic diversity of this iconic rare bird.摘要：人类活动介导的杂交事件已显著改变了全球范围内受胁类群的演化轨迹。尽管外来哺乳类捕食者、大范围生境丧失与退化已明确威胁到新西兰特有黑长脚鹬（black stilt，kakī，*Himantopus novaezelandiae*）的种群恢复与存续，但这一极危特有种与其自行扩散至当地的近缘种斑长脚鹬（pied stilt，poaka，*Himantopus himantopus leucocephalus*）之间的杂交风险仍尚不明确。本研究结合微卫星（microsatellite）数据的贝叶斯混合分析（Bayesian admixture analyses）与线粒体DNA（mitochondrial DNA）序列数据，对黑长脚鹬与斑长脚鹬间的杂交及渐渗（introgression）水平进行评估。研究结果显示，依据成体羽色被判定为杂交个体的鸟类确实属于杂交起源，且二者间的杂交既广泛存在，又呈双向发生。尽管如此，本研究几乎未发现斑长脚鹬向黑长脚鹬发生渐渗的证据，从而驳斥了"黑长脚鹬属于杂交群"这一主流观点。据我们所知，本研究是首个针对近期经历广泛人为介导双向杂交的受胁物种，证实其未发生广泛渐渗的综合性研究。我们将这一颇令人意外的结果部分归因于雌性杂交个体繁殖成功率下降，以及黑长脚鹬种群暂时性的雄性偏倚性比。为最大化黑长脚鹬的演化潜力，本研究基于上述数据提出保育管理建议，旨在维持这一标志性珍稀鸟类的遗传完整性，并最大化其遗传多样性。