Data from: Landscape effects on gene flow for a climate-sensitive montane species, the American pika

Climate change is arguably the greatest challenge to conservation of our time. Most vulnerability assessments rely on past and current species distributions to predict future persistence but ignore species' abilities to disperse through landscapes, which may be particularly important in fragmented habitats and crucial for long-term persistence in changing environments. Landscape genetic approaches explore the interactions between landscape features and gene flow and can clarify how organisms move among suitable habitats, but have suffered from methodological uncertainties. We used a landscape genetic approach to determine how landscape and climate-related features influence gene flow for American pikas (Ochotona princeps) in Crater Lake National Park. Pikas are heat intolerant and restricted to cool microclimates; thus, range contractions have been predicted as climate changes. We evaluated the correlation between landscape variables and genetic distance using partial Mantel tests in a causal modelling framework, and used spatially explicit simulations to evaluate methods of model optimization including a novel approach based on relative support and reciprocal causal modelling. We found that gene flow was primarily restricted by topographic relief, water and west-facing aspects, suggesting that physical restrictions related to small body size and mode of locomotion, as well as exposure to relatively high temperatures, limit pika dispersal in this alpine habitat. Our model optimization successfully identified landscape features influencing resistance in the simulated data for this landscape, but underestimated the magnitude of resistance. This is the first landscape genetic study to address the fundamental question of what limits dispersal and gene flow in the American pika.气候变化可以说是当代生物保护领域面临的最严峻挑战。多数物种脆弱性评估依赖于物种过往与当前的分布数据来预测其未来存续前景，却忽略了物种在景观中扩散的能力——这一能力在生境破碎化区域尤为关键，且对于物种在快速变化的环境中实现长期存续至关重要。景观遗传学（landscape genetics）方法旨在探究景观特征与基因流之间的相互作用，阐明生物如何在适宜生境间移动，但长期以来一直存在方法学层面的不确定性。本研究以美国火山口湖国家公园（Crater Lake National Park）内的北美鼠兔（Ochotona princeps）为研究对象，采用景观遗传学方法，明确景观与气候相关特征如何影响其基因流过程。鼠兔不耐高温，仅能依赖凉爽的微生境存活，因此据预测，随着气候变化，其分布范围将出现收缩。我们在因果建模框架下，通过偏曼特尔检验（partial Mantel test）评估景观变量与遗传距离之间的相关性，并借助空间显式模拟对多种模型优化方法进行验证，其中包括一种基于相对支持度与互逆因果建模的创新方法。研究结果显示，鼠兔的基因流主要受到地形起伏、水体以及西向坡向的限制，这表明与小型体型和运动模式相关的物理约束，加上较高的温度暴露程度，共同限制了该高山生境中鼠兔的扩散行为。我们的模型优化方法成功在该景观的模拟数据中识别出了影响扩散阻力的景观特征，但对阻力强度的估算存在低估。本研究是首个针对北美鼠兔扩散与基因流限制因素这一核心科学问题开展的景观遗传学研究。