An understanding of population structure and connectivity at multiple spatial scales is required to assist wildlife conservation and management. This is particularly critical for widely distributed and highly mobile marine mammals subject to fisheries by-catch. Here, we present a population genomic assessment of a near-top predator, the common dolphin (Delphinus delphis), which is incidentally caught in multiple fisheries across the Australasian region. The study was carried out using 14,799 ddRAD sequenced genome-wide markers genotyped for 478 individuals sampled at multiple spatial scales across Australasia. A complex hierarchical metapopulation structure was identified, with three highly distinct and genetically diverse regional populations at large spatial scales (>1,500 km). The populations inhabit the southern coast of Australia, the eastern coast of Australia, New Zealand, and Tasmania, with the latter also showing a considerable level of admixture to Australia's east coast. Each of these regional populations contained two to four nested local populations (i.e., subpopulations) at finer spatial scales, with most of the gene flow occurring within distances of 50 to 400 km. Estimates of contemporary migration rates between adjacent subpopulations ranged from 6 to 25%. Overall, our findings identified complex common dolphin population structure and connectivity across state and international jurisdictions, including migration and gene flow across the Tasman Sea. The results indicate that inter-jurisdictional collaboration is required to implement conservation management strategies and mitigate fisheries interactions of common dolphins across multiple spatial scales in the Australasian region.

需要了解多个空间尺度上的种群结构和连通性，以帮助野生动植物保护和管理。对于受到渔业副渔获物影响的广泛分布和高度流动的海洋哺乳动物而言，这尤其重要。在这里，我们介绍了一种近端捕食者，即普通海豚（翠雀），而该鱼偶然在整个澳大利亚地区的多个渔业中被捕。这项研究使用了14,799个ddRAD测序的全基因组标记，对在整个大洋洲多个空间尺度采样的478个人进行了基因分型。确定了一个复杂的层次结构的种群结构，具有三个高度不同且遗传上不同的区域人口，它们在较大的空间尺度（> 1,500 km）上。人口居住在澳大利亚的南海岸，澳大利亚的东海岸，新西兰和塔斯马尼亚岛，塔斯马尼亚岛也显示出与澳大利亚的东海岸相当程度的混杂。这些区域种群中的每一个在更精细的空间尺度上都包含2到4个嵌套的局部种群（即亚种群），大多数基因流发生在50到400 km的距离内。估计相邻亚群之间的当代迁徙率在6％至25％之间。总体而言，我们的发现确定了各州和国际管辖区之间复杂的常见海豚种群结构和连通性，包括跨塔斯曼海的迁移和基因流。结果表明，需要进行跨部门合作，以实施保护管理战略并减轻澳大利亚海豚在多个空间尺度上的共同海豚的渔业相互作用。