Data from: From global to local genetic structuring in the red gorgonian Paramuricea clavata: the interplay between oceanographic conditions and limited larval dispersal

Defining the scale of connectivity among marine populations and identifying the barriers to gene flow are tasks of fundamental importance for understanding the genetic structure of populations and for the design of marine reserves. Here we investigated the population genetic structure at three spatial scales of the red gorgonian Paramuricea clavata (Cnidaria, Octocorallia) a key species dwelling in the coralligenous assemblages of the Mediterranean Sea. Colonies of P. clavata were collected from 39 locations across the Mediterranean Sea from Morocco to Turkey and analysed using microsatellite loci. Within three regions (Medes, Marseille and North Corsica) sampling was obtained from multiple locations and at different depths. Three different approaches (measures of genetic differentiation, Bayesian clustering and spatially explicit maximum-difference algorithm) were used to determine the pattern of genetic structure. We identified genetic breaks in the spatial distribution of genetic diversity which were concordant with oceanographic conditions in the Mediterranean Sea. We revealed a high level of genetic differentiation among populations and a pattern of isolation by distance across the studied area and within the three regions, underlining short effective larval dispersal in this species. We observed genetic differentiation among populations in the same locality dwelling at different depths which may be explained by local oceanographic conditions and which may allow a process of local adaptation of the populations to their environment. We discuss the implications of our results for the conservation of the species which is exposed to various threats.

明确海洋种群间的连通性规模并鉴定基因流障碍，是解析种群遗传结构、规划海洋保护区的核心基础性任务。本研究以地中海珊瑚藻群落的关键物种——红柳珊瑚（*Paramuricea clavata*，刺胞动物门Cnidaria，八放珊瑚亚纲Octocorallia）为研究对象，在三个空间尺度上解析其种群遗传结构。研究团队从摩洛哥至土耳其的地中海海域39个采样点采集红柳珊瑚群体，并利用微卫星位点（microsatellite loci）进行遗传分析。在三个区域（梅德斯群岛、马赛及北科西嘉）内，研究团队从多个采样点的不同水深环境采集了样本。本研究采用三种分析方法——遗传分化度量、贝叶斯聚类（Bayesian clustering）以及空间显式最大差异算法（spatially explicit maximum-difference algorithm）——来解析种群遗传结构模式。研究发现遗传多样性的空间分布存在遗传断裂带，且该断裂带与地中海海洋水文条件高度吻合。研究结果显示种群间存在高水平遗传分化，且在整个研究区域及三个子区域内均呈现距离隔离模式，表明该物种的有效幼虫扩散距离较短。研究还观察到，同一采样点内不同水深的红柳珊瑚种群间存在遗传分化，这一现象可通过局地海洋水文条件解释，且可能为种群对环境的局地适应过程提供了契机。最后，本研究讨论了研究结果对该受多种威胁的红柳珊瑚物种的保护启示。