Data from: Geographic determinants of gene flow in two sister species of tropical Andean frogs

Complex interactions between topographic heterogeneity, climatic and environmental gradients, and thermal niche conservatism are commonly assumed to indicate the degree of biotic diversification in montane regions. Our aim was to investigate factors that disrupt gene flow between populations and to determine if there is evidence of downslope asymmetric migration in highland frogs with wide elevational ranges and thermal niches. We determined the role of putative impediments to gene flow (as measured by least-cost path (LCP) distances, topographic complexity, and elevational range) in promoting genetic divergence between populations of 2 tropical Andean frog sister species (Dendropsophus luddeckei, N = 114; Dendropsophus labialis, N = 74) using causal modeling and multiple matrix regression. Although the effect of geographic features was species specific, elevational range and LCP distances had the strongest effect on gene flow, with mean effect sizes (Mantel r and regression coefficients β), between 5 and 10 times greater than topographic complexity. Even though causal modeling and multiple matrix regression produced congruent results, the latter provided more information on the contribution of each geographic variable. We found moderate support for downslope migration. We conclude that the climatic heterogeneity of the landscape, the elevational distance between populations, and the inability to colonize suboptimal habitats due to thermal niche conservatism influence the magnitude of gene flow. Asymmetric migration, however, seems to be influenced by life history traits.

地形异质性（topographic heterogeneity）、气候与环境梯度（climatic and environmental gradients）以及热生态位保守性（thermal niche conservatism）之间的复杂相互作用，通常被认为可用于反映山地区域的生物类群分化程度。本研究旨在探究阻断种群间基因流（gene flow）的影响因子，并判定在具有宽泛海拔跨度与热生态位的高地蛙类中，是否存在下坡方向的不对称迁移。本研究采用因果建模（causal modeling）与多元矩阵回归（multiple matrix regression）方法，针对2种热带安第斯蛙类姊妹物种（sister species）（*Dendropsophus luddeckei*，样本量N=114；*Dendropsophus labialis*，样本量N=74）的种群间遗传分化（genetic divergence）驱动因子展开分析，以明确基因流潜在阻碍因子——通过最小成本路径（least-cost path, LCP）距离、地形复杂度（topographic complexity）以及海拔跨度（elevational range）表征——所发挥的作用。尽管地理特征的影响具有物种特异性，但海拔跨度与LCP距离对基因流的影响最为显著，其平均效应量（曼特尔r值（Mantel r）与回归系数β（regression coefficients β））较地形复杂度高出5至10倍。尽管因果建模与多元矩阵回归得到了一致的结果，但后者能够提供更多关于各地理变量贡献度的信息。本研究为下坡迁移提供了中等程度的支持证据。综上，本研究认为，地表气候异质性、种群间海拔距离，以及因热生态位保守性而无法占据亚适宜生境（suboptimal habitats）的特性，共同影响了基因流的强度。不过，不对称迁移似乎受到物种生活史特征（life history traits）的调控。