PDF(Pubmed)
Abstract：
Declines and extirpations of American pika (Ochotona princeps) 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 19th 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.
摘要：
在2000年代初期，文献中开始记录了历史上被占领的地点的美国鼠兔（Ochotonaprinceps）种群的减少和灭绝。与全球气候变化相称，外围和低海拔地区的许多损失与环境空气温度和降水状况的变化有关。这里,我们报告了美国标志性鼠兔群体的可用遗传资源下降，位于加利福尼亚州东部的BodieHills物种分布的西南边缘，美国。由坚硬岩石开采造成的高度分散的栖息地组成，大约在19世纪末，该地点的矿石堆放场可能被附近的天然距骨露头的鼠兔所占领。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（1948-1949，1988-1991，2013-2015）的三个不同采样点跟踪Bodiepikas的种群和斑块级遗传多样性。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性的降低。在1988-1991年和2013-2015年期间，对现有斑块进行了更广泛的采样，表明人口结构增加，有效人口规模减少。此外，过去51年的人口普查记录以及1947年从Wassuk山脉附近的鼠兔种群中收集的存档博物馆样本（内华达州，美国）为该地区发生的隔离和遗传合并增加提供了进一步的支持。这项研究强调了博物馆样本和长期监测在我们对人口生存能力的理解中的重要性。
