Data from: Climate variables explain neutral and adaptive variation within salmonid metapopulations: the importance of replication in landscape genetics

Understanding how environmental variation influences population genetic structure is important for conservation management because it can reveal how human stressors influence population connectivity, genetic diversity, and persistence. We used riverscape genetics modeling to assess whether climatic and habitat variables were related to neutral and adaptive patterns of genetic differentiation (population specific and pairwise FST) within five metapopulations (79 populations, 4,583 individuals) of steelhead trout (Oncorhynchus mykiss) in the Columbia River Basin, USA. Using 151 putatively neutral and 29 candidate adaptive SNP loci, we found that climate-related variables (winter precipitation, summer maximum temperature, winter highest 5% flow events, and summer mean flow) often explained neutral and adaptive patterns of genetic differentiation within metapopulations, suggesting that climatic variation likely influences both demography (neutral variation) and local adaptation (adaptive variation). However, we did not observe consistent relationships between climate variables and FST across all metapopulations, underscoring the need for replication when extrapolating results from one scale to another (e.g., basin-wide to the metapopulation scale). Sensitivity analysis (leave-one-population-out) revealed consistent relationships between climate variables and FST within three metapopulations; however, these patterns were not consistent in two metapopulations likely due to small sample sizes (N = 10). These results provide correlative evidence that climatic variation has shaped the genetic structure of steelhead populations and highlight the need for replication and sensitivity analyses in land and riverscape genetics.解析环境变异对种群遗传结构的调控机制，对于物种保护管理至关重要：其可揭示人类胁迫因子如何影响种群连通性、遗传多样性与种群存续能力。本研究借助河川景观遗传学（riverscape genetics）建模方法，针对美国哥伦比亚河流域内5个集合种群（metapopulation）（共79个种群、4583个个体）的硬头鳟（*Oncorhynchus mykiss*），评估气候与生境变量是否与种群遗传分化的中性模式及适应性模式（种群特异性FST与成对FST）相关。本研究利用151个推定中性单核苷酸多态性（SNP）位点与29个候选适应性SNP位点开展分析，结果显示气候相关变量（冬季降水量、夏季最高气温、冬季极端高流量事件（前5%流量阈值）及夏季平均流量）通常可解释集合种群内的遗传分化中性与适应性模式，表明环境变异或同时影响种群动态（中性变异）与局部适应性（适应性变异）。然而，本研究未在所有集合种群中观测到气候变量与FST间存在一致关联，这凸显了将研究结果从某一尺度外推至另一尺度（如全流域尺度到集合种群尺度）时开展重复验证的必要性。留一种群剔除敏感性分析显示，3个集合种群内气候变量与FST间存在一致关联；但另外2个集合种群未呈现该模式，这或因样本量较小（N=10）所致。本研究结果为环境变异塑造硬头鳟种群遗传结构提供了相关性证据，同时凸显了在陆地与河川景观遗传学研究中开展重复验证与敏感性分析的重要性。