Data from: Linking genetic and ecological differentiation in an ungulate with a circumpolar distribution

Genetic differentiation among populations may arise from the disruption of gene flow due to local adaptation to distinct environments and/or neutral accumulation of mutations and genetic drift resulted from geographical isolation. Quantifying the role of these processes in determining the genetic structure of natural populations remains challenging. Here, we analyze the relative contribution of isolation-by-resistance (IBR), isolation-by-environment (IBE), genetic drift and historical isolation in allopatry during Pleistocene glacial cycles on shaping patterns of genetic differentiation in caribou/reindeer populations (Rangifer tarandus) across the entire distribution range of the species. Our study integrates analyses at range-wide and regional scales to partial out the effects of historical and contemporary isolation mechanisms. At the circumpolar scale, our results indicate that genetic differentiation is predominantly explained by IBR and historical isolation. At a regional scale, we found that environmental dissimilarity and population size significantly explained the spatial distribution of genetic variation among populations belonging to the Euro-Beringian lineage within North America. In contrast, genetic differentiation among populations within the North American lineage was predominantly explained by IBR and population size, but not IBE. We also found discrepancies between genetic and ecotype designation across the Holarctic species distribution range. Overall, these results indicate that multiple isolating mechanisms have played roles in shaping the spatial distribution of genetic variation across the distribution range of a large mammal with high potential for gene flow. Considering multiple spatial scales and simultaneously testing a comprehensive suite of potential isolating mechanisms, our study contributes to understand the ecological and evolutionary processes underlying organism–landscape interactions.

种群间的遗传分化，可因物种对不同环境的局部适应阻断基因流而产生，亦可由地理隔离引发的突变中性积累与遗传漂变所导致。量化上述过程在决定自然种群遗传结构中的作用，仍是一项颇具挑战的研究课题。本研究以全球分布范围内的驯鹿（Rangifer tarandus）种群为研究对象，解析了抗性隔离（isolation-by-resistance, IBR）、环境隔离（isolation-by-environment, IBE）、遗传漂变以及更新世冰期阶段的异域地理隔离等过程对其遗传分化格局形成的相对贡献。本研究整合全域与区域尺度的分析，以剥离历史与当代隔离机制的影响。在环极尺度下，研究结果显示种群遗传分化主要由抗性隔离与历史隔离所解释。在区域尺度上，针对北美境内的欧亚-白令支系种群，我们发现环境差异与种群大小可显著解释种群间遗传变异的空间分布格局。与之相反，北美支系内部的种群遗传分化，则主要由抗性隔离与种群大小决定，而非环境隔离。本研究同时发现，在该全北界分布的物种整个分布范围内，遗传划分与生态型界定之间存在不一致之处。总体而言，上述结果表明，多种隔离机制共同塑造了这一具备高基因流潜力的大型哺乳动物的种群遗传变异空间分布格局。本研究兼顾多空间尺度，并同时测试了一系列潜在的隔离机制，有助于深入理解生物-景观互作背后的生态与进化过程。