Selective sweeps of mitochondrial DNA can drive the evolution of uniparental inheritance

While the uniparental (or maternal) inheritance of mitochondrial DNA (mtDNA) is widespread, the reasons for its evolution remain unclear. Two main hypotheses have been proposed: selection against individuals containing different mtDNAs (heteroplasmy) and selection against “selfish” mtDNA mutations. Recently, uniparental inheritance was shown to promote adaptive evolution in mtDNA, potentially providing a third hypothesis for its evolution. Here we explore this hypothesis theoretically and ask if the accumulation of beneficial mutations provides a sufficient fitness advantage for uniparental inheritance to invade a population in which mtDNA is inherited biparentally. In a deterministic model, uniparental inheritance increases in frequency but cannot replace biparental inheritance if only a single beneficial mtDNA mutation sweeps through the population. When we allow successive selective sweeps of mtDNA, however, uniparental inheritance can replace biparental inheritance. Using a stochast...尽管线粒体DNA（mitochondrial DNA, mtDNA）的单亲（或称母系）遗传模式广泛存在，但其演化的背后动因仍未明晰。目前已提出两种主流假说：一是针对携带异质性（heteroplasmy，即个体内存在多种线粒体DNA类型）的个体的选择压力，二是针对“自私”mtDNA突变的选择压力。近期研究表明，单亲遗传可促进mtDNA的适应性演化，这或许为解释其演化机制提供了第三种假说。本文从理论层面探究该假说，并探讨有益突变的积累是否能为单亲遗传带来足够的适合度优势，使其能够入侵以双亲方式遗传mtDNA的种群。在确定性模型（deterministic model）中，若仅存在单个有利mtDNA突变在种群中发生选择性清除（selective sweep），则单亲遗传的频率会上升，但无法完全取代双亲遗传。然而，当允许mtDNA发生多轮选择性清除时，单亲遗传便可彻底取代双亲遗传。我们采用随机（原文未完整）……