Local Adaptation by Alleles of Small Effect
Local Adaptation by Alleles of Small Effect
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DOI：
10.1086/682405
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发表时间：
2015-10-01
影响因子：
2.9
通讯作者：
Yeaman, Sam
中科院分区：
文献类型：
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作者：
Yeaman, Sam
种群遗传模型预测，选择系数小的等位基因可能会被迁移淹没，不会有助于当地的适应。但是，如果大多数等位基因对立木变异的影响很小，那么局部适应又是如何进行的呢？在这里，我回顾预测的人口和定量遗传模型，并使用基于个人的模拟来说明如何架构的本地适应依赖于遗传冗余的性状，维持常设遗传变异（V-G），和易感性的等位基因沼泽。即使群体遗传模型预测个别等位基因的沼泽化，如果有足够的V-G，相当大的局部适应可以在表型水平上进化。然而，在这种情况下，分歧的基础架构是短暂的：F-ST在所有基因座上都很低，并且没有基因座在很长时间内做出重要贡献。由于这种局部适应主要是由于瞬时频率变化和等位基因协方差，这些架构将是困难的，甚至不可能使用目前的方法来研究适应的基因组基础。即使当等位基因很大并且对沼泽有抵抗力时，如果遗传冗余和突变率很高，那么结构也可以是高度暂时的。这些结果表明，漂移可以发挥关键作用，在塑造本地适应的架构，无论是通过侵蚀V-G和影响周转率的多态性与冗余的表型效应。
Population genetic models predict that alleles with small selection coefficients may be swamped by migration and will not contribute to local adaptation. But if most alleles contributing to standing variation are of small effect, how does local adaptation proceed? Here I review predictions of population and quantitative genetic models and use individual-based simulations to illustrate how the architecture of local adaptation depends on the genetic redundancy of the trait, the maintenance of standing genetic variation (V-G), and the susceptibility of alleles to swamping. Even when population genetic models predict swamping for individual alleles, considerable local adaptation can evolve at the phenotypic level if there is sufficient V-G. However, in such cases the underlying architecture of divergence is transient: F-ST is low across all loci, and no locus makes an important contribution for very long. Because this kind of local adaptation is mainly due to transient frequency changes and allelic covariances, these architectures will be difficultif not impossibleto detect using current approaches to studying the genomic basis of adaptation. Even when alleles are large and resistant to swamping, architectures can be highly transient if genetic redundancy and mutation rates are high. These results suggest that drift can play a critical role in shaping the architecture of local adaptation, both through eroding V-G and affecting the rate of turnover of polymorphisms with redundant phenotypic effects.