Smith Shane R T, Connallon Tim
School of Biological Sciences, Monash University, Clayton, VIC, 3800, Australia.
Evolution. 2017 May;71(5):1417-1424. doi: 10.1111/evo.13238. Epub 2017 Apr 10.
Maternal inheritance of mitochondrial DNA (mtDNA) facilitates the evolutionary accumulation of mutations with sex-biased fitness effects. Whereas maternal inheritance closely aligns mtDNA evolution with natural selection in females, it makes it indifferent to evolutionary changes that exclusively benefit males. The constrained response of mtDNA to selection in males can lead to asymmetries in the relative contributions of mitochondrial genes to female versus male fitness variation. Here, we examine the impact of genetic drift and the distribution of fitness effects (DFE) among mutations-including the correlation of mutant fitness effects between the sexes-on mitochondrial genetic variation for fitness. We show how drift, genetic correlations, and skewness of the DFE determine the relative contributions of mitochondrial genes to male versus female fitness variance. When mutant fitness effects are weakly correlated between the sexes, and the effective population size is large, mitochondrial genes should contribute much more to male than to female fitness variance. In contrast, high fitness correlations and small population sizes tend to equalize the contributions of mitochondrial genes to female versus male variance. We discuss implications of these results for the evolution of mitochondrial genome diversity and the genetic architecture of female and male fitness.
线粒体DNA（mtDNA）的母系遗传促进了具有性别偏向适应性效应的突变的进化积累。虽然母系遗传使mtDNA的进化与雌性的自然选择紧密相关，但它对仅有利于雄性的进化变化却无动于衷。mtDNA对雄性选择的受限反应可能导致线粒体基因对雌性与雄性适应性变异的相对贡献出现不对称性。在此，我们研究了遗传漂变以及突变之间的适应性效应分布（DFE），包括两性间突变适应性效应的相关性，对线粒体适应性遗传变异的影响。我们展示了漂变、遗传相关性和DFE的偏度如何决定线粒体基因对雄性与雌性适应性方差的相对贡献。当两性间突变适应性效应的相关性较弱且有效种群规模较大时，线粒体基因对雄性适应性方差的贡献应远大于对雌性的贡献。相反，高适应性相关性和小种群规模倾向于使线粒体基因对雌性与雄性方差的贡献趋于相等。我们讨论了这些结果对线粒体基因组多样性进化以及雌性和雄性适应性遗传结构的影响。
