Department of Zoology, University of British Columbia, Vancouver, Canada V6T 1Z4
Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada.
Proc Biol Sci. 2018 Nov 7;285(1890):20181864. doi: 10.1098/rspb.2018.1864.
Despite decades of research, the factors that maintain genetic variation for fitness are poorly understood. It is unclear what fraction of the variance in a typical fitness component can be explained by mutation-selection balance (MSB) and whether fitness components differ in this respect. In theory, the level of standing variance in fitness due to MSB can be predicted using the rate of fitness decline under mutation accumulation, and this prediction can be directly compared to the standing variance observed. This approach allows for controlled statistical tests of the sufficiency of the MSB model, and could be used to identify traits or populations where genetic variance is maintained by other factors. For example, some traits may be influenced by sexually antagonistic balancing selection, resulting in an excess of standing variance beyond that generated by deleterious mutations. We describe the underlying theory and use it to test the MSB model for three traits in We find evidence for differences among traits, with MSB being sufficient to explain genetic variance in larval viability but not male mating success or female fecundity. Our results are consistent with balancing selection on sexual fitness components, and demonstrate the feasibility of rigorous statistical tests of the MSB model.
尽管已经进行了几十年的研究，但维持适合度遗传变异的因素仍知之甚少。目前尚不清楚典型适合度成分的方差中有多少可以用突变选择平衡（MSB）来解释，以及是否在这方面存在差异。从理论上讲，可以使用在突变积累下的适合度下降率来预测由于 MSB 而导致的适合度的固定方差水平，并且可以将此预测与观察到的固定方差直接进行比较。这种方法允许对 MSB 模型的充分性进行受控的统计检验，并可用于确定由其他因素维持遗传方差的特征或种群。例如，某些特征可能受到性拮抗平衡选择的影响，从而导致固定方差超出有害突变产生的方差。我们描述了基本理论，并将其用于检验三个特征的 MSB 模型，结果表明特征之间存在差异，MSB 足以解释幼虫存活率的遗传方差，但不足以解释雄性交配成功率或雌性繁殖力的遗传方差。我们的结果与性适合度成分的平衡选择一致，并证明了对 MSB 模型进行严格的统计检验是可行的。
