Department of Ecology, Evolution, and Organismal Biology, Iowa State University, 251 Bessey Hall, Ames, IA 50011, USA.
Mol Ecol. 2012 Jun;21(12):3078-93. doi: 10.1111/j.1365-294X.2012.05595.x. Epub 2012 Apr 30.
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 analysed 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 USA 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.
广泛存在的、具有移动能力的物种在没有明显地理屏障的情况下表现出遗传结构的潜力是一个日益受到关注的话题。然而，这些物种的结构模式和机制——尤其是在广泛的空间尺度上——仍然在很大程度上尚未得到探索。山猫分布于北美洲各地，具有许多促进基因流动的特征。为了测试历史、地形或生态因素是否影响了该物种的遗传分化，我们分析了来自其分布范围内的 1700 多个样本的 1kb 的 mtDNA 序列和 15 个微卫星位点。这两种标记类型的主要特征都涉及到一个具有明显过渡区（或缝合区）的纵向渐变，这个过渡区沿着大平原形成。因此，数据将美国东部和西部的山猫区分开来，基因流动没有明显的物理障碍。种群分析支持了一个从单独的更新世避难所扩张的情景，大平原代表了一个次要接触区。两个主要谱系内的亚结构可能反映了奠基者效应、生态因素、人为/地形效应或这些力量的组合。两条主要的地形特征，密西西比河和落基山脉，并没有被认为是显著的遗传障碍。生态区和环境相关性解释了一小部分但具有显著意义的遗传变异。总的来说，结果表明历史过程是导致广泛遗传分化的主要原因，但当代因素似乎也在促进和维持结构方面发挥了作用。尽管山猫具有移动性和广泛的生态位，但大规模的景观变化导致了显著而复杂的遗传结构模式。
