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影响机制，对于物种保护管理具有重要价值，其可揭示人类胁迫因子如何作用于种群连通性、遗传多样性及种群存续能力。本研究借助河流景观遗传学（riverscape genetics）建模手段，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遗传分化的中性模式及适应性模式（种群特异性FST及两两FST）存在关联。本研究采用151个推定中性单核苷酸多态性（Single Nucleotide Polymorphism, 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、冬季前5%高流量事件及夏季平均流量）往往能够解释集合种群内遗传分化的中性与适应性模式，表明气候变异可能同时影响种群动态（中性变异）与局部适应（适应性变异）。然而，本研究并未在所有集合种群中观测到气候变量与FST间存在一致的关联，这凸显了在将研究结果从某一尺度外推至另一尺度（如流域尺度至集合种群尺度）时开展重复研究的必要性。单种群剔除法敏感性分析结果表明，3个集合种群内的气候变量与FST间存在稳定关联；但由于样本量较小（N=10），该模式在另外2个集合种群中并不一致。本研究结果为气候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流景观遗传学研究中开展重复研究与敏感性分析的必要性。