Department of Fisheries and Wildlife, Oregon State University, Corvallis, Oregon, United States of America.
Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, United States of America.
PLoS One. 2018 Jul 11;13(7):e0199032. doi: 10.1371/journal.pone.0199032. eCollection 2018.
Genetic variation is the basis upon which natural selection acts to yield evolutionary change. In a rapidly changing environment, increasing genetic variation should increase evolutionary potential, particularly for small, isolated populations. However, the introduction of new alleles, either through natural or human-mediated processes, may have unpredictable consequences such as outbreeding depression. In this study, we identified a contact zone and limited gene flow between historically separated genetic lineages of American pikas (Ochotona princeps), representing the northern and southern Rocky Mountain subspecies, within Rocky Mountain National Park. The limited spatial extent of gene flow observed may be the result of geographic barriers to dispersal, selection against hybrid individuals, or both. Our fine-scale population genetic analysis suggests gene flow is limited but not completely obstructed by extreme topography such as glacial valleys, as well as streams including the Colorado River. The discovery of two subspecies within this single protected area has implications for monitoring and management, particularly in the light of recent analyses suggesting that the pikas in this park are vulnerable to fragmentation and local extinction under future projected climates. Future research should focus on the fitness consequences of introgression among distinct genetic lineages in this location and elsewhere, as well as within the context of genetic rescue as a conservation and management strategy for a climate sensitive species.
遗传变异是自然选择产生进化变化的基础。在快速变化的环境中，增加遗传变异应该会增加进化潜力，特别是对于小型、孤立的种群。然而，新等位基因的引入，无论是通过自然还是人为的过程，都可能产生不可预测的后果，如杂交衰退。在这项研究中，我们在落基山国家公园内确定了一个接触区和历史上分离的北美草原榛鼠（Ochotona princeps）遗传谱系之间有限的基因流，这些遗传谱系代表了落基山北部和南部的亚种。观察到的有限空间基因流可能是由于扩散的地理障碍、对杂交个体的选择，或两者兼而有之。我们的精细种群遗传分析表明，基因流虽然受到限制，但并没有被冰川谷等极端地形以及包括科罗拉多河在内的溪流完全阻断。在这个单一的保护区内发现了两个亚种，这对监测和管理具有重要意义，特别是考虑到最近的分析表明，该公园的草原榛鼠在未来预测的气候下容易受到碎片化和局部灭绝的影响。未来的研究应该集中在这个地点和其他地方不同遗传谱系之间基因渗入的适应后果，以及作为一个对气候敏感物种的保护和管理策略的遗传拯救方面。
