Data from: Geographic isolation and larval dispersal shape seascape genetic patterns differently according to spatial scale

Genetic variation, as a basis of evolutionary change, allows species to adapt and persist in different climates and environments. Yet, a comprehensive assessment of the drivers of genetic variation at different spatial scales is still missing in marine ecosystems. Here, we investigated the influence of environment, geographic isolation, and larval dispersal on the variation in allele frequencies, using an extensive spatial sampling (47 locations) of the striped red mullet (Mullus surmuletus) in the Mediterranean Sea. Univariate multiple regressions were used to test the influence of environment (salinity and temperature), geographic isolation, and larval dispersal on Single Nucleotide Polymorphisms (SNPs) allele frequencies. We used Moran’s Eigenvector Maps (db-MEMs) and Asymmetric Eigenvector Maps (AEMs) to decompose geographic and dispersal distances in predictors representing different spatial scales. We found that salinity and temperature had only a weak effect on the variation in allele frequencies. Our results revealed the predominance of geographic isolation to explain variation in allele frequencies at large spatial scale (> 1,000km) while larval dispersal was the major predictor at smaller spatial scale (< 1,000km). Our findings stress the importance of including spatial scales to understand the drivers of spatial genetic variation. We suggest that larval dispersal allows to maintain gene flows at small to intermediate scale, while at broad scale, genetic variation may be mostly shaped by adult mobility, demographic history or multi-generational stepping stone dispersal. These findings bring out important spatial scale considerations to account for in the design of a protected areas network that would efficiently enhance protection and persistence capacity of marine species.

遗传变异作为进化改变的基础，赋予物种适应不同气候与环境并得以存续的能力。然而，当前海洋生态系统领域仍缺乏针对不同空间尺度下遗传变异驱动因素的系统性评估。本研究以地中海海域条纹红羊鱼（Mullus surmuletus）为研究对象，通过覆盖47个采样点的大范围空间采样，探究了环境因子、地理隔离以及幼体扩散对等位基因频率变异的影响。研究采用单变量多元回归方法，检验了环境因子（盐度与水温）、地理隔离以及幼体扩散对单核苷酸多态性（Single Nucleotide Polymorphisms，SNPs）等位基因频率的影响。同时，本研究借助莫兰特征向量图（Moran’s Eigenvector Maps，db-MEMs）与非对称特征向量图（Asymmetric Eigenvector Maps，AEMs），对代表不同空间尺度的预测变量中的地理距离与扩散距离进行分解。结果显示，盐度与水温对等位基因频率变异的影响微弱。研究表明，在大空间尺度（>1000千米）下，地理隔离是解释等位基因频率变异的主导因素；而在小空间尺度（<1000千米）下，幼体扩散则为主要预测因子。本研究结果强调，在解析空间遗传变异的驱动机制时，纳入空间尺度维度具有重要意义。本研究提出，幼体扩散可维持中小尺度下的基因流；而在大尺度下，遗传变异或主要由成体移动能力、种群历史或多代踏脚石扩散所塑造。本研究结果可为海洋物种保护区网络的设计提供关键的空间尺度考量依据，助力提升海洋物种的保护成效与种群存续能力。