Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, QC G1V 0A6, Canada.
Genes (Basel). 2021 Apr 3;12(4):524. doi: 10.3390/genes12040524.
The interplay between recombination rate, genetic drift and selection modulates variation in genome-wide ancestry. Understanding the selective processes at play is of prime importance toward predicting potential beneficial or negative effects of supplementation with domestic strains (i.e., human-introduced strains). In a system of lacustrine populations supplemented with a single domestic strain, we documented how population genetic diversity and stocking intensity produced lake-specific patterns of domestic ancestry by taking the species' local recombination rate into consideration. We used 552 Brook Charr () from 22 small lacustrine populations, genotyped at ~32,400 mapped SNPs. We observed highly variable patterns of domestic ancestry between each of the 22 populations without any consistency in introgression patterns of the domestic ancestry. Our results suggest that such lake-specific ancestry patterns were mainly due to variable associative overdominance (AOD) effects among populations (i.e., potential positive effects due to the masking of possible deleterious alleles in low recombining regions). Signatures of AOD effects were also emphasized by highly variable patterns of genetic diversity among and within lakes, potentially driven by predominant genetic drift in those small isolated populations. Local negative effects such as negative epistasis (i.e., potential genetic incompatibilities between the native and the introduced population) potentially reflecting precursory signs of outbreeding depression were also observed at a chromosomal scale. Consequently, in order to improve conservation practices and management strategies, it became necessary to assess the consequences of supplementation at the population level by taking into account both genetic diversity and stocking intensity when available.
重组率、遗传漂变和选择之间的相互作用调节了全基因组祖先的变化。了解发挥作用的选择过程对于预测补充家养种群（即人类引入的种群）的潜在有益或负面影响至关重要。在一个补充了单一家养种群的湖泊种群系统中，我们记录了群体遗传多样性和放养强度如何通过考虑物种的局部重组率来产生特定于湖泊的家养祖先模式。我们使用了来自 22 个小湖泊种群的 552 条 Brook Charr（），这些种群在约 32400 个映射的 SNP 上进行了基因分型。我们观察到在 22 个种群中的每一个之间都存在高度可变的家养祖先模式，而没有任何内流模式的一致性。我们的结果表明，这种特定于湖泊的祖先模式主要是由于群体之间可变的关联超显性（AOD）效应（即由于在重组率低的区域中可能有害等位基因的掩盖而产生的潜在积极影响）。在湖泊内和湖泊之间遗传多样性的高度可变模式也强调了 AOD 效应的特征，这可能是由这些小隔离种群中主要的遗传漂变驱动的。在染色体水平上还观察到了局部负效应，例如负遗传相互作用（即本地种群和引入种群之间可能存在遗传不相容性），这可能反映了远缘杂交衰退的前兆迹象。因此，为了改善保护实践和管理策略，有必要在群体水平上评估补充的后果，在可行的情况下，同时考虑遗传多样性和放养强度。
