Vagile, large-bodied marine organisms frequently have wide range dispersion but also dependence on coastal habitats for part of their life history. These characteristics may induce complex population genetic structure patterns, with resulting implications for the management of exploited populations. The scalloped hammerhead, Sphyrna lewini , is a cosmopolitan, migratory shark in tropical and warm temperate waters, inhabiting coastal bays during parturition and juvenile development, and the open ocean as adults. Here, we investigated the genetic connectivity and diversity of S. lewini in the western Atlantic using large sample coverage (N = 308), and data from whole mitochondrial control region (mtCR) sequences and ten nuclear microsatellite markers We detected significant population genetic structure with both mtCR and microsatellites markers (mtCR: Φ ST = 0.60; p < 0.001; microsatellites: D est 0.0794, p = 0.001, F ST = 0.046, p < 0.05), and isolation by distance (mtCR r = 0.363, p = 0.009; microsatellites markers r = 0.638, p = 0.007). Migration and gene flow patterns were asymmetric and female reproductive philopatry is postulated to explain population subdivisions. The notable population differentiation at microsatellites markers indicates low-levels of male-mediated gene flow in the western Atlantic. The overall effective population size was estimated as 299 (215–412 CI), and there was no evidence of strong or recent bottleneck effects. Findings of at least three management units, moderate genetic diversity, and low effective population size in the context of current overfishing calls for intensive management aimed at short and long-term conservation for this endangered species in the western Atlantic Ocean.

中文翻译：

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全球濒临灭绝的锤头鲨的受限连通性和种群遗传脆弱性

多变的大型海洋生物通常分布范围很广，但在其部分生活史中也依赖沿海栖息地。这些特征可能会导致复杂的种群遗传结构模式，从而对被开发种群的管理产生影响。扇形锤头鲨 Sphyrna lewini 是一种世界性的迁徙鲨鱼，生活在热带和暖温带水域，在分娩和幼年发育期间栖息在沿海海湾，成年后则栖息在开阔的海洋中。在这里，我们使用大样本覆盖率（N = 308）调查了西大西洋 S. lewini 的遗传连通性和多样性，以及来自整个线粒体控制区 (mtCR) 序列和十个核微卫星标记的数据我们使用 mtCR 和微卫星标记（mtCR：Φ ST = 0.60；p < 0.001；微卫星：D est 0.0794，p = 0.001， F ST = 0.046，p < 0.05），以及按距离隔离（mtCR r = 0.363，p = 0.009；微卫星标记 r = 0.638，p = 0.007）。迁移和基因流动模式是不对称的，假设女性生殖亲缘关系可以解释种群细分。微卫星标记处显着的种群分化表明西大西洋中雄性介导的基因流水平较低。总体有效人口规模估计为 299 (215–412 CI)，没有证据表明存在强烈或近期的瓶颈效应。