Rapid genetic adaptation to a novel ecosystem despite a large founder event
Rapid genetic adaptation to a novel ecosystem despite a large founder event
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尽管发生了大型创始人事件，但基因仍能快速适应新的生态系统
DOI：
10.1111/mec.17121
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发表时间：
2023
影响因子：
4.9
通讯作者：
Christie, Mark R.
中科院分区：
文献类型：
--
作者：
Sparks, Morgan M.;Schraidt, Claire E.;Yin, Xiaoshen;Seeb, Lisa W.;Christie, Mark R.
外来物种和入侵物种是研究快速进化的极好的自然实验。在这里，我们描述的影响，遗传漂变和快速的遗传适应粉红鲑鱼（虹鳟gorbuscha），不小心引入到五大湖通过一个单一的引进事件31代前。通过对134条鱼进行全基因组重测序，跨越了原生和引进范围内的5个样本组，我们估计，在引进时，源种群的有效种群规模为146，886，而创始种群的有效种群规模仅为72-减少了2040倍。正如严重的创始人事件所预期的那样，我们发现全基因组遗传多样性的测量结果减少，特别是SNP数量减少37.7%，观察到的杂合性减少8.2%。尽管这种遗传多样性下降，我们提供的证据，在47个基因座的多条染色体的引进人口，包括与昼夜节律，免疫反应和成熟，这符合预期或已知的表型变化在五大湖的基因的错义变异的推定选择。对于其中一个基因，我们使用基于物种特异性代理的模型来排除遗传漂变，并得出结论，我们的结果支持对发生在周期基因（per 2）中的选择的强烈反应，该基因在确定生物体的每日生物钟中起着主导作用，与重要的物候期引入的鲑鱼所经历的大日长差异相匹配。总之，这些结果告诉我们，即使只有一小部分遗传变异，种群也可能迅速进化到新的环境。
Introduced and invasive species make excellent natural experiments for investigating rapid evolution. Here, we describe the effects of genetic drift and rapid genetic adaptation in pink salmon (Oncorhynchus gorbuscha) that were accidentally introduced to the Great Lakes via a single introduction event 31 generations ago. Using whole‐genome resequencing for 134 fish spanning five sample groups across the native and introduced range, we estimate that the source population's effective population size was 146,886 at the time of introduction, whereas the founding population's effective population size was just 72—a 2040‐fold decrease. As expected with a severe founder event, we show reductions in genome‐wide measures of genetic diversity, specifically a 37.7% reduction in the number of SNPs and an 8.2% reduction in observed heterozygosity. Despite this decline in genetic diversity, we provide evidence for putative selection at 47 loci across multiple chromosomes in the introduced populations, including missense variants in genes associated with circadian rhythm, immunological response and maturation, which match expected or known phenotypic changes in the Great Lakes. For one of these genes, we use a species‐specific agent‐based model to rule out genetic drift and conclude our results support a strong response to selection occurring in a period gene (per2) that plays a predominant role in determining an organism's daily clock, matching large day length differences experienced by introduced salmon during important phenological periods. Together, these results inform how populations might evolve rapidly to new environments, even with a small pool of standing genetic variation.