Data from: Ocean circulation model predicts high genetic structure in a long-lived pelagic developer

Understanding the movement of genes and individuals across marine seascapes is a long-standing challenge in marine ecology, and can inform our understanding of local adaptation, the persistence and movement of populations, and the spatial scale of effective management. Patterns of gene flow in the ocean are often inferred based on population genetic analyses coupled with knowledge of species’ dispersive life histories. However, genetic structure is the result of time-integrated processes, and may not capture present-day connectivity between populations. Here we use a high-resolution oceanographic circulation model to predict larval dispersal along the complex coastline of western Canada that includes the transition between two well-studied zoogeographic provinces. We simulate dispersal in a benthic sea star with a 6-10 week pelagic larval phase, and test predictions of this model against previously observed genetic structure including a strong phylogeographic break within the zoogeographical transition zone. We also test predictions with new genetic sampling in a site within the phylogeographic break. We find that the coupled genetic and circulation model predicts the high degree of genetic structure observed in this species, despite its long pelagic duration. High genetic structure on this complex coastline can thus be explained through ocean circulation patterns which tend to retain passive larvae within 20 - 50 km of their parents, suggesting a necessity for close-knit design of Marine Protected Area networks.

解析基因与个体在海洋景观中的迁移模式是海洋生态学领域长期存在的核心难题，该研究可为我们理解局部适应、种群存续与扩散以及有效管理的空间尺度提供关键依据。海洋中的基因流（gene flow）模式通常通过种群遗传分析（population genetic analyses）结合物种扩散型生活史特征推导得出。然而，种群遗传结构（genetic structure）是时间整合过程的产物，未必能反映种群间当前的连通状况。本研究采用高分辨率海洋环流模型（oceanographic circulation model），对加拿大西部复杂海岸线沿线的幼体扩散情况进行预测——该区域涵盖两个已被广泛研究的动物地理省（zoogeographic province）之间的过渡地带。我们针对一种浮游幼体期（pelagic larval phase）持续6至10周的底栖海星（benthic sea star）开展扩散模拟，并将模型预测结果与此前观测到的种群遗传结构进行验证，其中该遗传结构包含动物地理过渡带内显著的系统地理断裂（phylogeographic break）。我们还通过系统地理断裂带内某一站点的新增遗传采样，对模型预测结果进行了验证。研究发现，尽管该类群拥有较长的浮游幼体期，但耦合遗传与环流的模型仍能准确预测该物种中观测到的高度遗传结构。该复杂海岸线上的高度遗传结构可通过海洋环流模式得到解释：此类环流会将被动扩散的幼体滞留在亲体周边20至50公里范围内，这表明构建紧密连通的海洋保护区（Marine Protected Area）网络具有必要性。