Department of Biology, Stanford University, Stanford, CA 94305-5020, USA.
Mol Ecol. 2009 Dec;18(23):4775-89. doi: 10.1111/j.1365-294X.2009.04382.x. Epub 2009 Oct 27.
Assessing the relative role of evolutionary processes on genetic diversity is critical for understanding species response to climatic change. However, many processes, independent of climate, can lead to the same genetic pattern. Because effective population size and gene flow are affected directly by abundance and dispersal, population ecology has the potential to profoundly influence patterns of genetic variation over microevolutionary timescales. Here, we use aDNA data and simulations to explore the influence of population ecology and Holocene climate change on genetic diversity of the Uinta ground squirrel (Spermophilus armatus). We examined phylochronology from three modern and two ancient populations spanning the climate transitions of the last 3000 years. Population genetic analyses based on summary statistics suggest that changes in genetic diversity and structure coincided with the Medieval Warm Period (MWP), c. 1000 years ago. Serial coalescent simulations allowed us to move beyond correlation with climate to statistically compare the likelihoods of alternative population histories given the observed data. The data best fit source-sink models that include large, mid-elevation populations that exchange many migrants and small populations at the elevational extremes. While the MWP is likely to have reduced genetic diversity, our model-testing approach revealed that MWP-driven changes in genetic structure were not better supported for the range of models explored. Our results point to the importance of species ecology in understanding responses to climate, and showcase the use of ancient genetic data and simulation-based inference for unraveling the relative roles of microevolutionary processes.
评估进化过程对遗传多样性的相对作用对于理解物种对气候变化的响应至关重要。然而，许多与气候无关的过程可能导致相同的遗传模式。由于有效种群大小和基因流直接受到丰度和扩散的影响，种群生态学有可能在微观进化时间尺度上深刻影响遗传变异模式。在这里，我们使用 aDNA 数据和模拟来探索种群生态学和全新世气候变化对犹他囊地鼠（Spermophilus armatus）遗传多样性的影响。我们检查了跨越过去 3000 年气候转变的三个现代和两个古代种群的系统发育年代学。基于汇总统计数据的群体遗传分析表明，遗传多样性和结构的变化与中世纪暖期（MWP）相吻合，大约在 1000 年前。连续的合并模拟使我们能够超越与气候的相关性，根据观察到的数据统计比较替代种群历史的可能性。数据最符合包括许多移民和高海拔极端地区小种群在内的大型中海拔源汇模型。虽然 MWP 可能降低了遗传多样性，但我们的模型测试方法表明，在探索的模型范围内，MWP 驱动的遗传结构变化并没有得到更好的支持。我们的研究结果表明，物种生态学在理解对气候的响应方面非常重要，并展示了使用古代遗传数据和基于模拟的推理来揭示微观进化过程的相对作用。
