Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra), Barcelona, Spain.
Research Unit of Biodiversity (UO-CSIC-PA), Oviedo University, Asturias, Spain.
Front Zool. 2013 May 20;10(1):28. doi: 10.1186/1742-9994-10-28.
Ancient DNA has revolutionized conservation genetic studies as it allows monitoring of the genetic variability of species through time and predicting the impact of ecosystems' threats on future population dynamics and viability. Meanwhile, the consequences of anthropogenic activities and climate change to island faunas, particularly seabirds, remain largely unknown. In this study, we examined temporal changes in the genetic diversity of a threatened seabird, the Cory's shearwater (Calonectris borealis).
We analysed the mitochondrial DNA control region of ancient bone samples from the late-Holocene retrieved from the Canary archipelago (NE Atlantic) together with modern DNA sequences representative of the entire breeding range of the species. Our results show high levels of ancient genetic diversity in the Canaries comparable to that of the extant population. The temporal haplotype network further revealed rare but recurrent long-distance dispersal between ocean basins. The Bayesian demographic analyses reveal both regional and local population size expansion events, and this is in spite of the demographic decline experienced by the species over the last millennia.
Our findings suggest that population connectivity of the species has acted as a buffer of genetic losses and illustrate the use of ancient DNA to uncover such cryptic genetic events.
古 DNA 彻底改变了保护遗传学研究，因为它允许通过时间监测物种的遗传变异性，并预测生态系统威胁对未来种群动态和生存能力的影响。与此同时，人类活动和气候变化对岛屿动物群的影响，特别是海鸟，在很大程度上仍未被了解。在这项研究中，我们研究了受威胁的海鸟——冠毛小海雀（Calonectris borealis）遗传多样性的时间变化。
我们分析了从加那利群岛（北大西洋东北部）取回的晚全新世古代骨骼样本的线粒体 DNA 控制区，以及代表该物种整个繁殖范围的现代 DNA 序列。我们的结果表明，加那利群岛的古代遗传多样性水平与现存种群相当高。时间单倍型网络进一步显示了罕见但反复发生的跨大洋远距离扩散。贝叶斯人口统计分析显示，该物种在过去几千年中经历了人口减少，但仍存在区域性和局部性的种群规模扩张事件。
我们的研究结果表明，该物种的种群连通性起到了遗传损失的缓冲作用，并说明了古 DNA 可用于揭示这些隐藏的遗传事件。
