Dynamics of Neutral and Selected Alleles When the Offspring Distribution Is Skewed
Dynamics of Neutral and Selected Alleles When the Offspring Distribution Is Skewed
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DOI：
10.1534/genetics.112.140038
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发表时间：
2012-08-01
期刊：
影响因子：
3.3
通讯作者：
Plotkin, Joshua B.
中科院分区：
文献类型：
--
作者：
Der, Ricky;Epstein, Charles;Plotkin, Joshua B.
我们在一个简单的种群模型中分析了两个可选等位基因的动态，该模型允许在后代数量分布上的大家庭规模。这种人口模型首先由Eldon和Wakeley提出，他们在假设中立的情况下描述了抽样个体之间的回溯时间谱系关系。我们研究了等位基因频率在有或没有选择的情况下相应的前向动态。我们推导了一个连续近似，类似于Kimura的扩散近似，我们描述了三种不同的行为机制，这些行为机制对应于Eldon和Wakeley的凝聚过程中的不同机制。我们证明，与具有相同方差的有效种群大小的Wright-Fisher模型相比，Eldon-Wakeley模型中的选择效应被强烈放大。值得注意的是，尽管存在遗传漂变，但在Eldon-Wakeley模型中，一个有利的等位基因甚至可以被保证固定。根据对太平洋牡蛎家庭规模的估计，我们计算了这种行为在太平洋牡蛎种群中所需的选择系数。我们的分析强调，具有相同有效种群规模的种群可能会经历完全不同形式的遗传漂变，这取决于生殖机制，并对由此产生的等位基因动态产生重大影响。
We analyze the dynamics of two alternative alleles in a simple model of a population that allows for large family sizes in the distribution of offspring number. This population model was first introduced by Eldon and Wakeley, who described the backward-time genealogical relationships among sampled individuals, assuming neutrality. We study the corresponding forward-time dynamics of allele frequencies, with or without selection. We derive a continuum approximation, analogous to Kimura's diffusion approximation, and we describe three distinct regimes of behavior that correspond to distinct regimes in the coalescent processes of Eldon and Wakeley. We demonstrate that the effect of selection is strongly amplified in the Eldon-Wakeley model, compared to the Wright-Fisher model with the same variance effective population size. Remarkably, an advantageous allele can even be guaranteed to fix in the Eldon-Wakeley model, despite the presence of genetic drift. We compute the selection coefficient required for such behavior in populations of Pacific oysters, based on estimates of their family sizes. Our analysis underscores that populations with the same effective population size may nevertheless experience radically different forms of genetic drift, depending on the reproductive mechanism, with significant consequences for the resulting allele dynamics.