The Genetic Basis of Phenotypic Adaptation I: Fixation of Beneficial Mutations in the Moving Optimum Model
The Genetic Basis of Phenotypic Adaptation I: Fixation of Beneficial Mutations in the Moving Optimum Model
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DOI：
10.1534/genetics.108.099820
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发表时间：
2009-05-01
期刊：
影响因子：
3.3
通讯作者：
Hermisson, Joachim
中科院分区：
文献类型：
--
作者：
Kopp, Michael;Hermisson, Joachim
我们研究的遗传基础的适应在一个移动的最佳模型，其中的数量性状的最佳值随着时间的推移以恒定的速度增加。我们首先分析了一个单位点两等位基因模型与复发突变，我们得到准确的分析近似（i）的时间，在此之前有害的等位基因变得有益的，（ii）等待时间为一个成功的新的突变，（iii）的时间的mu等位基因需要达到固定。在这些结果的基础上，我们表明，最短的总固定时间是等位基因与中间表型效应。我们推导出一个近似的这种“最佳”的效果，我们表明，它依赖于一个简单的方式上的复合参数，它集成了生态参数和遗传结构的特点。在第二步中，我们使用多位点模型的随机计算机模拟来研究具有不同影响的突变等位基因固定的顺序。与单基因座结果一致，具有中间效应的等位基因倾向于比具有小或大效应的等位基因更早固定。然而，效果。最快突变的大小与单基因座模型中预测的不同。我们展示了这些差异如何通过多位点遗传学的两种特定效应来解释。最后，我们讨论了我们的结果在光的三个相关的时间尺度在系统中的环境，突变和固定的时间尺度，定义三个参数制度导致轮胎自适应替代模式的定性差异。
We study the genetic basis of adaptation in a moving optimum model, in which the optimal value for a quantitative trait increases over time at a constant rate. We first analyze a one-locus two-allele model with recurrent mutation, for which we derive accurate analytical approximations for (i) the time at which a previously deleterious allele becomes beneficial, (ii) the waiting time for a successful new mutation, and (iii) the time the mutantallele needs to reach fixation. On the basis of these results, we show that the shortest total time to fixation is for alleles with intermediate phenotypic effect. We derive an approximation for this "optimal" effect, and we show that it depends in a simple way on a composite parameter which integrates the ecological parameters and the genetic architecture of the trait. In a second step, we use stochastic computer simulations of a multilocus model to study the order in which mutant alleles with different effects go to fixation. In agreement with the one-locus results, alleles with intermediate effect tend to become fixed earlier than those with either small or large effects. However, the effect. size of the fastest mutations differs from the one predicted in the one-locus model. We show how these differences can be explained by two specific effects of multilocus genetics. Finally, we discuss our results in the light of three relevant timescales acting in the system-the environmental, mutation, and fixation timescales-which define three parameter regimes leading to qualitative differences in tire adaptive substitution pattern.