Hoekstra R F
Department of Plant Sciences, Wageningen University, The Netherlands.
Hum Reprod. 2000 Jul;15 Suppl 2:102-11. doi: 10.1093/humrep/15.suppl_2.102.
In the great majority of sexual organisms, cytoplasmic genomes such as the mitochondrial genome are inherited (almost) exclusively through only one, usually the maternal, parent. This rule probably evolved to minimize the potential spread of selfish cytoplasmic genomic mutations through a species. Maternal inheritance creates an asymmetry between the sexes from which several evolutionary consequences follow. Because natural selection on mitochondria operates only in females, mitochondrial mutations may have more deleterious effects in males than in females. Strictly uniparental inheritance creates asexual mitochondrial lineages that are vulnerable to mutation accumulation (Muller's ratchet). There is evidence that over evolutionary time mitochondrial genomes have indeed accumulated slightly deleterious mutations. Mutation accumulation in animal mitochondrial genomes is probably slowed down mainly by two processes: a severe reduction in germline mitochondrial genome copy number at some point in the life cycle, enabling more effective elimination of mutations by natural selection, and occasional recombination between maternal and paternal mitochondrial genomes following paternal leakage.
在绝大多数有性生殖生物中，细胞质基因组（如线粒体基因组）几乎完全仅通过一方亲本遗传，通常是母本。这条规则的演化可能是为了尽量减少自私的细胞质基因组突变在一个物种中的潜在传播。母系遗传造成了两性之间的不对称，由此产生了一些进化后果。由于对线粒体的自然选择仅在雌性中起作用，线粒体突变对雄性可能比对雌性具有更多有害影响。严格的单亲遗传产生了易受突变积累影响的无性线粒体谱系（缪勒棘轮效应）。有证据表明，随着时间的推移，线粒体基因组确实积累了一些轻微有害的突变。动物线粒体基因组中的突变积累可能主要通过两个过程减缓：在生命周期的某个阶段，生殖系线粒体基因组拷贝数大幅减少，从而使自然选择能够更有效地消除突变；以及在父系渗漏后，母本和父本线粒体基因组偶尔发生重组。
