Data from: Effects of the landscape on boreal toad gene flow: does the pattern-process relationship hold true across distinct landscapes at the northern range margin?

Understanding the impact of natural and anthropogenic landscape features on population connectivity is a major goal in evolutionary ecology and conservation. Discovery of dispersal barriers is important for predicting population responses to landscape and environmental changes, particularly for populations at geographic range margins. We used a landscape genetics approach to quantify the effects of landscape features on gene flow and connectivity of boreal toad (Bufo boreas) populations from two distinct landscapes in Southeast Alaska (Admiralty Island, ANM, and the Chilkat River Valley, CRV). We used two common methodologies for calculating resistance distances in landscape genetics studies (resistance based on least-cost paths and circuit theory). We found a strong effect of saltwater on genetic distance of CRV populations, but no landscape effects were found for the ANM populations. Our discordant results show the importance of examining multiple landscapes that differ in the variability of their features, in order to maximize detectability of underlying processes and allow results to be broadly applicable across regions. Saltwater serves as a physiological barrier to boreal toad gene flow and affects populations on a small geographic scale, yet there appear to be few other barriers to toad dispersal in this intact northern region.

探究自然与人为景观特征对种群连通性的影响，是进化生态学与保护生物学领域的核心研究目标之一。识别扩散障碍，对于预测种群对景观及环境变化的响应至关重要，尤其针对地理分布边缘的种群。本研究采用景观遗传学方法，量化了阿拉斯加东南部两处截然不同的景观——阿德默勒尔蒂岛（Admiralty Island, ANM）与奇尔卡特河谷（Chilkat River Valley, CRV）——内北方蟾蜍（boreal toad, Bufo boreas）种群的基因流与连通性所受景观特征的影响。本研究采用景观遗传学研究中两种常用的阻力距离计算方法：基于最小成本路径的阻力法与电路理论法。研究发现，咸水对奇尔卡特河谷种群的遗传距离存在显著影响，但阿德默勒尔蒂岛种群未表现出任何与景观特征相关的遗传效应。本研究得到的不一致性结果表明，为最大化对潜在生态过程的检测能力，并使研究结果可在区域间广泛推广，需对景观特征异质性存在差异的多类景观展开研究。咸水可作为北方蟾蜍基因流的生理屏障，并在较小地理尺度上影响种群动态，但在这片保存完好的北部区域内，似乎几乎不存在其他阻碍蟾蜍扩散的障碍。