A pattern of population structure called isolation-by-environment (IBE) evolves when gene flow connecting populations in different habitats is lower than expected. Although IBE is widespread, there is limited information on its magnitude compared with other factors influencing gene flow. We estimated the relative importance of IBE in the frog Rana temporaria in the Swiss Alps, a geographic context in which IBE should be relatively pronounced. The environmental factor potentially causing IBE was the length of the growing season, which is highly correlated with elevation. A sample of 992 individuals from 82 breeding sites were genotyped at 1827 single-nucleotide polymorphism markers; gene flow was estimated in four ways related to FST , genetic distance, allele sharing, and distance on a population graph. Gravity modeling and random forest regression evaluated the importance of six at-site covariates, 10 between-site covariates, and geographic distance. There was broad agreement among analysis methods and measures of gene flow: isolation-by-distance (IBD) and habitat quality between sites were of highest importance, the elevation and ruggedness of the dispersal path were about half as important, and IBE was about 10-20% as important as IBD. These results combine with other evidence to suggest that population divergence across elevational gradients is underway in amphibians.

中文翻译：

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在高山两栖动物中环境隔离和基因流动的其他决定因素的相对重要性

当连接不同栖息地种群的基因流低于预期时，就会形成一种称为环境隔离 (IBE) 的种群结构模式。尽管 IBE 很普遍，但与影响基因流动的其他因素相比，关于其大小的信息有限。我们估计了 IBE 在瑞士阿尔卑斯山的青蛙 Rana temporaria 中的相对重要性，在该地理环境中 IBE 应该相对显着。可能导致 IBE 的环境因素是生长季节的长度，这与海拔高度相关。对来自 82 个繁殖地的 992 个个体的样本进行了 1827 个单核苷酸多态性标记的基因分型；基因流以四种与 FST、遗传距离、等位基因共享和种群图上的距离相关的方式进行估计。重力建模和随机森林回归评估了 6 个现场协变量、10 个现场协变量和地理距离的重要性。基因流的分析方法和测量方法之间存在广泛的一致性：距离隔离 (IBD) 和地点之间的栖息地质量最重要，传播路径的海拔和崎岖程度大约是其重要程度的一半，而 IBE 大约为 10 -20% 与 IBD 一样重要。这些结果与其他证据相结合，表明两栖动物正在发生跨海拔梯度的种群分化。传播路径的海拔和崎岖程度大约是 IBD 的重要程度的一半，而 IBE 的重要性大约是 IBD 的 10-20%。这些结果与其他证据相结合，表明两栖动物正在发生跨海拔梯度的种群分化。传播路径的海拔和崎岖程度大约是 IBD 的重要程度的一半，而 IBE 的重要性大约是 IBD 的 10-20%。这些结果与其他证据相结合，表明两栖动物正在发生跨海拔梯度的种群分化。