Data from: Global population genetic dynamics of a highly migratory, apex predator shark

Knowledge of genetic connectivity dynamics in the world's large-bodied, highly migratory, apex predator sharks across their global ranges is limited. One such species, the tiger shark (Galeocerdo cuvier), occurs worldwide in warm-temperate and tropical waters, uses remarkably diverse habitats (nearshore to pelagic), and possesses a generalist diet that can structure marine ecosystems through top down processes. We investigated the phylogeography and global population structure of this exploited, phylogenetically enigmatic shark by using 10 nuclear microsatellites (n = 380) and sequences from the mitochondrial control region (CR, n = 340) and cytochrome oxidase I gene (n = 100). All three marker classes showed genetic differentiation between tiger sharks from the western Atlantic and Indo-Pacific ocean basins (microsatellite FST > 0.129; CR ΦST > 0.497), the presence of North vs. South western Atlantic differentiation, and isolation of tiger sharks sampled from Hawaii from other surveyed locations. Furthermore, mitochondrial DNA revealed high levels of intra ocean-basin matrilineal population structure, suggesting female philopatry and sex-biased gene flow. Coalescent- and genetic distance-based estimates of divergence from CR sequences were largely congruent (dcorr = 0.0015-0.0050), indicating a separation of Indo-Pacific and western Atlantic tiger sharks < 1 million years ago. Mitochondrial haplotype relationships suggested the western South Atlantic Ocean was likely a historical connection for inter-ocean basin linkages via dispersal around South Africa. Together, the results reveal unexpectedly high levels of population structure in a highly migratory, behaviorally generalist, cosmopolitan ocean predator, calling for management and conservation on smaller than anticipated spatial scales.目前学界对全球范围内大型、高度洄游的顶级捕食鲨鱼在其全球分布区内的遗传连通动态认知仍较为有限。其中虎鲨（Galeocerdo cuvier）便是这类物种之一：它们广泛分布于全球暖温带与热带海域，栖息类型极为多样（覆盖近岸至远洋海域），且食性泛化，可通过自上而下的生态过程塑造海洋生态系统结构。本研究针对这一兼具渔业捕捞压力且系统发育地位存疑的虎鲨，依托10个核微卫星标记（n=380）、线粒体控制区（mitochondrial control region, CR，n=340）以及细胞色素氧化酶I基因（cytochrome oxidase I gene，n=100）的序列数据，解析其系统地理学特征与全球种群结构。三类分子标记均显示：西大西洋与印度-太平洋海域的虎鲨种群间存在显著遗传分化（微卫星标记FST>0.129；线粒体控制区ΦST>0.497）；西大西洋南北海域种群间亦存在分化；夏威夷海域采样的虎鲨与其余所有调查区域种群相互隔离。此外，线粒体DNA分析揭示海域内存在高水平的母系种群结构，提示雌性个体存在恋巢行为且基因流存在性别偏倚。基于线粒体控制区序列的溯祖分析与遗传距离法得到的分化时间估算结果基本一致（dcorr=0.0015~0.0050），表明印度-太平洋与西大西洋的虎鲨种群分化发生在不足100万年前。线粒体单倍型的亲缘关系分析显示，西南大西洋海域可能是历史上跨洋盆种群联系的关键纽带，即通过南非周边海域完成跨洋扩散。综合来看，本研究结果揭示：这种高度洄游、行为泛化的全球性海洋顶级捕食者，其种群结构分化程度远超预期，这要求我们在比此前预想更小的空间尺度上开展虎鲨的管理与保护工作。