Department of Biology, Stanford University, Stanford, California 94305.
Genetics. 2013 Sep;195(1):231-42. doi: 10.1534/genetics.113.152496. Epub 2013 Jul 12.
Frequency-dependent selection (FDS) remains a common heuristic explanation for the maintenance of genetic variation in natural populations. The pairwise-interaction model (PIM) is a well-studied general model of frequency-dependent selection, which assumes that a genotype's fitness is a function of within-population intergenotypic interactions. Previous theoretical work indicated that this type of model is able to sustain large numbers of alleles at a single locus when it incorporates recurrent mutation. These studies, however, have ignored the impact of the distribution of fitness effects of new mutations on the dynamics and end results of polymorphism construction. We suggest that a natural way to model mutation would be to assume mutant fitness is related to the fitness of the parental allele, i.e., the existing allele from which the mutant arose. Here we examine the numbers and distributions of fitnesses and alleles produced by construction under the PIM with mutation from parental alleles and the impacts on such measures due to different methods of generating mutant fitnesses. We find that, in comparison with previous results, generating mutants from existing alleles lowers the average number of alleles likely to be observed in a system subject to FDS, but produces polymorphisms that are highly stable and have realistic allele-frequency distributions.
频率依赖选择（FDS）仍然是解释自然种群中遗传变异维持的常见启发式解释。成对相互作用模型（PIM）是一种研究充分的频率依赖选择的通用模型，它假设基因型的适合度是种群内基因型间相互作用的函数。先前的理论工作表明，当这种模型包含反复突变时，它能够在单个基因座上维持大量的等位基因。然而，这些研究忽略了新突变的适应度效应分布对多态性构建的动态和最终结果的影响。我们认为，模拟突变的一种自然方式是假设突变体的适合度与亲本等位基因的适合度有关，即突变体产生的现有等位基因。在这里，我们研究了在 PIM 下从亲本等位基因产生突变的情况下构建的适合度和等位基因的数量和分布，以及突变适合度生成方法对这些度量的影响。我们发现，与以前的结果相比，从现有等位基因产生突变体降低了在受 FDS 影响的系统中可能观察到的等位基因的平均数量，但产生了高度稳定且具有现实等位基因频率分布的多态性。
