Polygenic selection within a single generation leads to subtle divergence among ecological niches

Selection on standing genetic variation may be effective enough to allow for adaptation to distinct niche environments within a single generation. Minor allele frequency changes at multiple, redundant loci of small effect can produce remarkable phenotypic shifts. Yet, demonstrating rapid adaptation via polygenic selection in the wild remains challenging. Here we harness natural replicate populations that experience similar selection pressures and harbor high within-, yet negligible among-population genetic variation. Such populations can be found among the teleost Fundulus heteroclitus which inhabits marine estuaries characterized by high environmental heterogeneity. We identify 10,861 single nucleotide polymorphisms in F. heteroclitus that belong to a single, panmictic population yet reside in environmentally distinct niches (one coastal basin and three replicate tidal ponds). By sampling at two time-points within a single generation we quantify both allele frequency change within as w...基于现存遗传变异的选择或许具备足够效力，可使生物在单一代际内适应不同的生态位环境。多个微效冗余基因座上的次要等位基因频率改变，可引发显著的表型转变。然而，在野生环境中通过多基因选择验证快速适应性演化仍颇具挑战。本研究利用了一类自然重复种群：这类种群承受相似的选择压力，且种群内部遗传变异水平较高，但种群间遗传变异可忽略不计。这类种群可见于栖息于环境异质性极高的海洋河口的硬骨鱼类——底鳉（Fundulus heteroclitus）种群中。我们在底鳉（F. heteroclitus）中鉴定出10861个单核苷酸多态性位点（single nucleotide polymorphisms，SNPs），这些位点所属的种群为单一泛交种群，但这些位点所处的生态位环境各不相同（包含1个沿海海湾与3个重复潮汐池塘）。我们在单一代际内选取两个时间点开展采样，以此量化种群内的等位基因频率变化及相关指标（原文此处存在截断）