Abstract：
The long-term persistence of a population which has suffered a bottleneck partly depends on how historical demographic dynamics impacted its genetic diversity and the accumulation of deleterious mutations. Here we provide genomic evidence for the genetic effect of a recent population bottleneck in the endangered black-faced spoonbill (Platalea minor) after its rapid population recovery. Our data suggest that the bird\'s effective population size, Ne , had been relatively stable (7500-9000) since 22,000 years ago; however, a recent brief yet severe bottleneck (Ne = 20) which we here estimated to occur around the 1940s wiped out >99% of its historical Ne in roughly three generations. Despite a >15-fold population recovery since 1988, we found that black-faced spoonbill population has higher levels of inbreeding (7.4 times more runs of homozygosity) than its sister species, the royal spoonbill (P. regia), which is not thought to have undergone a marked population contraction. Although the two spoonbills have similar levels of genome-wide genetic diversity, our results suggest that selection on more genes was relaxed in the black-faced spoonbill; moreover individual black-faced spoonbills carry more putatively deleterious mutations (Grantham\'s score > 50), and may therefore express more deleterious phenotypic effects than royal spoonbills. Here we demonstrate the value of using genomic indices to monitor levels of genetic erosion, inbreeding and mutation load in species with conservation concerns. To mitigate the prolonged negative genetic effect of a population bottleneck, we recommend that all possible measures should be employed to maintain population growth of a threatened species.
摘要：
遭受瓶颈的人口的长期持久性部分取决于历史人口动态如何影响其遗传多样性和有害突变的积累。在这里，我们提供了基因组证据，证明了濒临灭绝的黑面琵琶（Plataleaminor）在快速恢复种群后最近的种群瓶颈的遗传效应。我们的数据表明，鸟类的有效种群数量，Ne,自22,000年前以来一直相对稳定（7500-9000）；然而，最近的一个短暂而严重的瓶颈（Ne=20），我们在这里估计发生在1940年代左右，在大约三代的时间内消灭了超过99％的历史Ne。尽管自1988年以来种群恢复了超过15倍，但我们发现黑脸琵琶种群的近亲繁殖水平高于其姐妹物种（纯合子的7.4倍），皇家琵琶（P.地亚)，这被认为没有经历过明显的人口收缩。尽管这两个琵鹭具有相似的全基因组遗传多样性水平，我们的结果表明，对更多基因的选择是放松的黑面琵琶;此外，个别黑面琵琶携带更多的推定有害突变（格兰瑟姆的分数>50），因此可能比皇家琵琶表现出更有害的表型效应。在这里，我们证明了使用基因组指数来监测遗传侵蚀水平的价值，具有保护问题的物种的近亲繁殖和突变负荷。为了减轻人口瓶颈的长期负面遗传效应，我们建议采取一切可能的措施来维持受威胁物种的种群增长。
