Stability and Response of Polygenic Traits to Stabilizing Selection and Mutation
Stability and Response of Polygenic Traits to Stabilizing Selection and Mutation
复制标题
DOI：
10.1534/genetics.113.159111
复制
发表时间：
2014-06-01
期刊：
影响因子：
3.3
通讯作者：
Barton, Nick
中科院分区：
文献类型：
--
作者：
de Vladar, Harold P.;Barton, Nick
当多基因性状处于稳定选择下时，许多不同的等位基因组合允许接近最佳适应。如果等位基因具有相同的效应，则导致与最优值的相同偏差的所有组合都是等效的。此外，由突变选择平衡维持的遗传方差为每个位点2 μ/S，其中P1是突变率，S是稳定选择的强度。实际上，等位基因的作用各不相同，这使得适应度景观不对称，并使均衡分析复杂化。我们表明，由此产生的遗传方差取决于固定附近的等位基因的分数，这有助于2亩/S，并在总的突变效应的等位基因是在中间频率。稳定选择和突变之间的相互作用导致了一个急剧的转变：等位基因的影响小于2根亩/S的阈值保持多态性，而那些具有较大的影响是固定的。平衡中的遗传负荷小于相同效应的性状，适应度平衡更相似。我们发现，如果最佳的是位移，等位基因的影响接近阈值扫描第一，和他们的增长率是有界的根μ S。长期反应通常会导致适应良好的性状，而不像同等效应的情况下，往往最终在一个次优的健身高峰。然而，种群收敛到的特定峰值对初始状态和最优性状值的移动速度非常敏感。
When polygenic traits are under stabilizing selection, many different combinations of alleles allow close adaptation to the optimum. If alleles have equal effects, all combinations that result in the same deviation from the optimum are equivalent. Furthermore, the genetic variance that is maintained by mutation selection balance is 2 mu/S per locus, where p, is the mutation rate and S the strength of stabilizing selection. In reality, alleles vary in their effects, making the fitness landscape asymmetric and complicating analysis of the equilibria. We show that that the resulting genetic variance depends on the fraction of alleles near fixation, which contribute by 2 mu/S, and on the total mutational effects of alleles that are at intermediate frequency. The interplay between stabilizing selection and mutation leads to a sharp transition: alleles with effects smaller than a threshold value of 2 root mu/S remain polymorphic, whereas those with larger effects are fixed. The genetic load in equilibrium is less than for traits of equal effects, and the fitness equilibria are more similar. We find that if the optimum is displaced, alleles with effects close to the threshold value sweep first, and their rate of increase is bounded by root mu S. Long-term response leads in general to well-adapted traits, unlike the case of equal effects that often end up at a suboptimal fitness peak. However, the particular peaks to which the populations converge are extremely sensitive to the initial states and to the speed of the shift of the optimum trait value.