Data from: Pleistocene and ecological effects on continental-scale genetic differentiation in the bobcat (Lynx rufus)

The potential for widespread, mobile species to exhibit genetic structure without clear geographic barriers is a topic of growing interest. Yet the patterns and mechanisms of structure – particularly over broad spatial scales – remain largely unexplored for these species. Bobcats occur across North America and possess many characteristics expected to promote gene flow. To test whether historical, topographic, or ecological factors have influenced genetic differentiation in this species, we analyzed 1 KB mtDNA sequence and 15 microsatellite loci from over 1700 samples collected across its range. The primary signature in both marker types involved a longitudinal cline with a sharp transition, or suture zone, occurring along the Great Plains. Thus, the data distinguished bobcats in the eastern U.S. from those in the western half, with no obvious physical barrier to gene flow. Demographic analyses supported a scenario of expansion from separate Pleistocene refugia, with the Great Plains representing a zone of secondary contact. Substructure within the two main lineages likely reflected founder effects, ecological factors, anthropogenic/topographic effects, or a combination of these forces. Two prominent topographic features, the Mississippi River and Rocky Mountains, were not supported as significant genetic barriers. Ecological regions and environmental correlates explained a small but significant proportion of genetic variation. Overall, results implicate historical processes as the primary cause of broad-scale genetic differentiation, but contemporary forces seem to also play a role in promoting and maintaining structure. Despite the bobcat’s mobility and broad niche, large-scale landscape changes have contributed to significant and complex patterns of genetic structure.

无明确地理屏障的广布移动物种展现遗传结构的可能性，是一个日益受到关注的研究议题。然而这类物种的遗传结构模式与形成机制，尤其是在大空间尺度下的相关研究，仍未得到充分探索。短尾猫（bobcat）广泛分布于北美大陆，具备诸多理论上可促进基因交流的生物学特征。为验证历史、地形或生态因素是否对该物种的遗传分化产生影响，我们对覆盖其整个分布范围的1700余份样本中的1千碱基对线粒体DNA（mtDNA）序列与15个微卫星位点（microsatellite loci）进行了分析。两类分子标记的核心信号均呈现沿经度梯度的渐变模式，且在美国大平原沿线存在一处尖锐的过渡区域——即缝合带（suture zone）。据此，本研究的数据将美国东部的短尾猫种群与西部种群区分开来，二者之间未发现阻碍基因交流的明显物理屏障。种群历史分析支持了"该物种从多个独立的更新世避难所（Pleistocene refugia）扩张，且大平原为次生接触带"的演化场景。两个主要支系内部的亚结构，可能源于奠基者效应（founder effects）、生态因素、人为活动或地形影响，或是这些因素共同作用的结果。密西西比河与落基山脉这两处典型地形特征，未被证实为显著的遗传屏障。生态区域与环境关联因子仅解释了一小部分但具有统计学显著性的遗传变异。总体而言，研究结果表明历史进程是该物种大尺度遗传分化的主要成因，但当代演化压力似乎也在推动并维持其遗传结构方面发挥了作用。尽管短尾猫具备较强的移动能力与广泛的生态位适应性，大规模的景观变化仍促成了复杂且显著的遗传结构模式。