Data from: Rapid evolution of cheating mitochondrial genomes in small yeast populations

Outcrossed sex exposes genes to competition with their homologues, allowing alleles that transmit more often than their competitors to spread despite organismal fitness costs. Mitochondrial populations in species with biparental inheritance are thought to be especially susceptible to such cheaters because they lack strict transmission rules like meiosis or maternal inheritance. Yet the interaction between mutation and natural selection in the evolution of cheating mitochondrial genomes has not been tested experimentally. Using yeast experimental populations, we show that although cheaters were rare in a large sample of spontaneous respiratory-deficient mitochondrial mutations (petites), cheaters evolve under experimentally enforced outcrossing even when mutation supply and selection are restricted by repeatedly bottlenecking populations.

异交有性生殖会使基因与其同源染色体产生竞争，使得那些传递频率高于竞争等位基因的等位基因，即便会带来个体适合度成本，也能够得以扩散。学界普遍认为，具有双亲遗传特性的物种类群的线粒体种群，尤其容易受到这类作弊型遗传元件的侵扰，因为它们缺乏减数分裂或母系遗传这类严格的传递规则。然而，目前尚未有实验验证突变与自然选择之间的相互作用，对作弊型线粒体基因组演化的影响。本研究以酵母实验种群为模型开展实验，结果显示：尽管在大量自发呼吸缺陷型线粒体突变（petites，即小菌落突变）的样本中，作弊型线粒体基因组较为罕见，但即便通过反复实施种群瓶颈操作以限制突变供应与自然选择强度，在实验强制施加异交的条件下，作弊型线粒体基因组仍会发生演化。