Data from: Regional variation in drivers of connectivity for two frog species (Rana pretiosa and R. luteiventris) from the U.S. Pacific Northwest

Comparative landscape genetics has uncovered high levels of variation in which landscape factors affect connectivity among species and regions. However, the relative importance of species traits vs. environmental variation for predicting landscape patterns of connectivity is unresolved. We provide evidence from a landscape genetics study of two sister taxa of frogs, the Oregon spotted frog (Rana pretiosa) and the Columbia spotted frog (R. luteiventris) in Oregon and Idaho, USA. Rana pretiosa is relatively more dependent on moisture for dispersal than R. luteiventris for dispersal, so if species traits influence connectivity, we predicted that connectivity among R. pretiosa populations would be more positively associated with moisture than R. luteiventris. However, if environmental differences are important drivers of gene flow, we predicted that connectivity would be more positively related to moisture in arid regions. We tested these predictions using eight microsatellite loci and gravity models in two R. pretiosa regions and four R. luteiventris regions (n = 1,168 frogs). In R. pretiosa, but not R. luteiventris, connectivity was positively related to mean annual precipitation, supporting our first prediction. In contrast, connectivity was not more positively related to moisture in more arid regions. Various temperature metrics were important predictors for both species and in all regions, but the directionality of their effects varied. Our results indicate that connectivity in R. pretiosa may be negatively impacted by reduction in mean annual precipitation. Overall, the pattern of variation in drivers of connectivity was consistent with predictions based on species traits rather than on environmental variation.比较景观遗传学（comparative landscape genetics）研究已发现，不同景观因子对物种及区域间连通性的影响存在高度异质性。然而，在预测连通性的景观格局时，物种性状与环境变异的相对重要性仍未明确。本研究以美国俄勒冈州与爱达荷州的两种蛙类姊妹类群——俄勒冈斑蛙（Rana pretiosa）与哥伦比亚斑蛙（R. luteiventris）为研究对象，通过景观遗传学分析提供了相关证据。相较于哥伦比亚斑蛙，俄勒冈斑蛙的扩散过程对水分条件的依赖程度更高。据此，若物种性状对种群连通性存在调控作用，我们预测俄勒冈斑蛙种群间的连通性与水分条件的正相关程度会显著高于哥伦比亚斑蛙。反之，若环境差异是基因流（gene flow）的核心驱动因子，则我们预测在干旱区域内，种群连通性与水分条件的正相关关系会更为显著。我们采用8个微卫星位点（microsatellite loci）与重力模型（gravity models），对2个俄勒冈斑蛙研究区域与4个哥伦比亚斑蛙研究区域开展了预测检验，样本总量为1168只蛙。分析结果显示，仅在俄勒冈斑蛙种群中，连通性与年平均降水量呈显著正相关，这验证了我们的第一项预测。与之相对，在干旱程度更高的区域中，连通性与水分条件的正相关关系并未显著增强。各类温度指标对两种蛙类的所有研究区域均具有连通性预测价值，但其影响方向存在差异。本研究结果表明，年平均降水量的减少可能会对俄勒冈斑蛙的种群连通性产生负面影响。整体而言，连通性驱动因子的变异模式与基于物种性状的预测结果相符，而非与基于环境变异的预测结果一致。