Center for Evolution & Medicine, School of Life Sciences, Arizona State University, Tempe, AZ, 85821, USA.
Heredity (Edinb). 2020 Feb;124(2):253-262. doi: 10.1038/s41437-019-0285-0. Epub 2019 Nov 27.
Recent advances in genomics have enabled researchers to shed light on the evolutionary processes driving human adaptation, by revealing the genetic architectures underlying traits ranging from lactase persistence, to skin pigmentation, to hypoxic response, to arsenic tolerance. Complicating the identification of targets of positive selection in modern human populations is their complex demographic history, characterized by population bottlenecks and expansions, population structure, migration, and admixture. In particular, founder effects and recent strong population size reductions, such as those experienced by the indigenous peoples of the Americas, have severe impacts on genetic variation that can lead to the accumulation of large allele frequency differences between populations due to genetic drift rather than natural selection. While distinguishing the effects of demographic history from selection remains challenging, neglecting neutral processes can lead to the incorrect identification of candidate loci. We here review the recent population genomic insights into the genetic basis of arsenic tolerance in Andean populations, and utilize this example to highlight both the difficulties pertaining to the identification of local adaptations in strongly bottlenecked populations, as well as the importance of controlling for demographic history in selection scans.
基因组学的最新进展使研究人员能够揭示从乳糖耐受、皮肤色素沉着、低氧反应到砷耐受等特征背后的遗传结构，从而深入了解人类适应的进化过程。在现代人类群体中识别正选择的目标变得复杂，其特点是人口瓶颈和扩张、人口结构、迁移和混合。特别是创始效应和近期强烈的人口减少，如美洲原住民所经历的，对遗传变异产生了严重影响，这可能导致由于遗传漂变而不是自然选择，种群之间的等位基因频率差异积累。尽管区分人口历史和选择的影响仍然具有挑战性，但忽视中性过程可能会导致候选基因座的错误识别。在这里，我们回顾了关于安第斯人群砷耐受遗传基础的最新群体基因组学研究进展，并利用这个例子突出了在强烈瓶颈化的种群中识别局部适应的困难，以及在选择扫描中控制人口历史的重要性。
