The conversion of variance and the evolutionary potential of restricted recombination

Genetic recombination is usually considered to facilitate adaptive evolution. However, recombination prevents the reliable cotransmission of interacting gene combinations and can disrupt complexes of coadapted genes. If interactions between genes have important fitness effects, restricted recombination may lead to evolutionary responses that are different from those predicted from a purely additive model and could even aid adaptation. Theory and data have demonstrated that phenomena that limit the effectiveness of recombination via increasing homozygosity, such as inbreeding and population subdivision and bottlenecks, can temporarily increase the additive genetic variance available to these populations. This effect has been attributed to the conversion of nonadditive to additive genetic variance. Analogously, phenomena such as chromosomal inversions and apomictic parthenogenesis that physically restrict recombination in part or all of the genome may also result in a release of additive variance. Here, we review and synthesize literature concerning the evolutionary potential of populations with effectively or physically restricted recombination. Our goal is to emphasize the common theme of increased short-term access to additive genetic variance in all of these situations and to motivate research directed towards a more complete characterization of the relevance of the conversion of variance to the evolutionary process.

基因重组通常被认为有助于适应性进化。然而，重组会阻碍相互作用的基因组合的可靠共传递，并可能破坏协同适应的基因复合体。如果基因之间的相互作用对适应性有重要影响，受限的重组可能导致与纯加性模型所预测的不同的进化反应，甚至可能有助于适应。理论和数据表明，通过增加纯合性来限制重组效果的现象，例如近亲繁殖、种群细分和瓶颈效应，可以暂时增加这些种群可利用的加性遗传方差。这种效应归因于非加性遗传方差向加性遗传方差的转化。类似地，像染色体倒位和无融合生殖的孤雌生殖等在部分或全部基因组中物理性限制重组的现象，也可能导致加性方差的释放。在此，我们回顾并综合了有关有效或物理性限制重组的种群的进化潜力的文献。我们的目标是强调在所有这些情况下短期增加获得加性遗传方差这一共同主题，并推动旨在更全面地描述方差转化对进化过程的相关性的研究。