Ferguson Jake M, Buzbas Erkan Ozge
Center for Modeling Complex Interactions, University of Idaho, United States.
Department of Statistical Science, University of Idaho, United States.
Theor Popul Biol. 2018 Jul;122:78-87. doi: 10.1016/j.tpb.2018.03.004. Epub 2018 Mar 21.
The distribution of allele frequencies obtained from diffusion approximations to Wright-Fisher models is useful in developing intuition about the population level effects of evolutionary processes. The statistical properties of the stationary distributions of K-allele models have been extensively studied under neutrality or under selection. Here, we introduce a new family of Wright-Fisher models in which there are two hierarchical levels of genetic variability. The genotypes composed of alleles differing from each other at the selected level have fitness differences with respect to each other and evolve under selection. The genotypes composed of alleles differing from each other only at the neutral level have the same fitness and evolve under neutrality. We show that with an appropriate scaling of the mutation parameter with respect to the number of alleles at each level, the frequencies of alleles at the selected and the neutral level are conditionally independent of each other, conditional on knowing the number of alleles at all levels. This conditional independence allows us to simulate from the joint stationary distribution of the allele frequencies. We use these simulated frequencies to perform inference on parameters of the model with two levels of genetic variability using Approximate Bayesian Computation.
从对赖特 - 费希尔模型的扩散近似中获得的等位基因频率分布，有助于直观理解进化过程在种群水平上的影响。K等位基因模型的平稳分布的统计特性已在中性或选择条件下得到广泛研究。在此，我们引入一类新的赖特 - 费希尔模型，其中存在两个层次的遗传变异性。在选定层次上彼此不同的等位基因组成的基因型，相互之间具有适合度差异，并在选择作用下进化。仅在中性层次上彼此不同的等位基因组成的基因型具有相同的适合度，并在中性条件下进化。我们表明，通过对每个层次上等位基因数量进行适当的突变参数缩放，在知道所有层次上等位基因数量的条件下，选定层次和中性层次上等位基因的频率相互条件独立。这种条件独立性使我们能够从等位基因频率的联合平稳分布进行模拟。我们使用这些模拟频率，通过近似贝叶斯计算对具有两个遗传变异层次的模型参数进行推断。
