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，对于保护管理工作至关重要，因其可揭示人类干扰因素如何作用于种群连通性、遗传多样性及种群存续能力。本研究采用河流景观遗传学（riverscape genetics）建模手段，针对美国哥伦比亚河流域内的5个集合种群（metapopulation，含79个种群、总计4583个个体）中的硬头鳟（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相关——涵盖种群特异性遗传分化指数（FST）与两两种群间FST。研究使用151个推定中性单核苷酸多态性位点（SNP loci）与29个候选适应性SNP loci，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）往往能够解释集合种群内遗传分化的中性与适应性模式，这表明气候变异或同时影响种群动态（中性遗传变异）与局部适应（适应性遗传变异）。然而，本研究并未在所有集合种群中观测到气候变量与FST之间的一致关联，这凸显了在将某一尺度的研究结果外推至另一尺度（如从全流域尺度推至集合种群尺度）时开展重复研究的必要性。留一种群法（leave-one-population-out）敏感性分析结果表明，在3个集合种群中，气候变量与FST之间存在稳定关联；但在另外2个集合种群中，该模式并不一致，这一现象大概率缘于其样本量较小（N=10）。本研究结果提供了相关性证据，证实气候变异塑造了硬头鳟种群的遗传结构，并强调了在陆地及河流景观遗传学研究中开展重复研究与敏感性分析的重要性。