Department of Environmental Conservation, University of Massachusetts Amherst, Amherst, Massachusetts, United States.
Department of Life Sciences, Santa Monica College, Santa Monica, California, United States.
PeerJ. 2023 Sep 28;11:e15962. doi: 10.7717/peerj.15962. eCollection 2023.
Declines and extirpations of American pika ( populations at historically occupied sites started being documented in the literature during the early 2000s. Commensurate with global climate change, many of these losses at peripheral and lower elevation sites have been associated with changes in ambient air temperature and precipitation regimes. Here, we report on a decline in available genetic resources for an iconic American pika metapopulation, located at the southwestern edge of the species distribution in the Bodie Hills of eastern California, USA. Composed of highly fragmented habitat created by hard rock mining, the ore dumps at this site were likely colonized by pikas around the end of the 19 century from nearby natural talus outcrops. Genetic data extracted from both contemporary samples and archived natural history collections allowed us to track population and patch-level genetic diversity for Bodie pikas across three distinct sampling points during the last half- century (1948-1949, 1988-1991, 2013-2015). Reductions in within-population allelic diversity and expected heterozygosity were observed across the full time period. More extensive sampling of extant patches during the 1988-1991 and 2013-2015 periods revealed an increase in population structure and a reduction in effective population size. Furthermore, census records from the last 51 years as well as archived museum samples collected in 1947 from a nearby pika population in the Wassuk range (Nevada, USA) provide further support of the increasing isolation and genetic coalescence occurring in this region. This study highlights the importance of museum samples and long-term monitoring in contextualizing our understanding of population viability.
美国雪兔（Ochotona princeps）的数量减少和灭绝（自 21 世纪初以来，文献中开始记录历史上有其栖息地的种群数量减少和灭绝情况。与全球气候变化相一致，许多外围和低海拔地区的这些种群损失都与环境空气温度和降水模式的变化有关。在这里，我们报告了美国加利福尼亚州东部博迪山（Bodie Hills）物种分布区西南边缘一个标志性的美国雪兔复合种群的可用遗传资源减少的情况。该复合种群由硬岩采矿产生的高度碎片化栖息地组成，这些矿渣堆可能是在 19 世纪末，从附近的天然碎石露头由雪兔殖民的。从当代样本和存档的自然历史收藏中提取的遗传数据使我们能够在过去半个世纪的三个不同采样点（1948-1949 年、1988-1991 年和 2013-2015 年）跟踪博迪雪兔的种群和斑块水平遗传多样性。在整个时间段内，观察到种群内等位基因多样性和预期杂合度减少。在 1988-1991 年和 2013-2015 年期间对现存斑块进行更广泛的采样揭示了种群结构的增加和有效种群规模的减少。此外，过去 51 年的普查记录以及 1947 年从内华达州 Wassuk 山脉（美国）附近雪兔种群中收集的存档博物馆样本进一步支持了该地区正在发生的隔离和遗传融合的增加。这项研究强调了博物馆样本和长期监测在使我们对种群生存能力的理解背景化方面的重要性。
