Department of Ecology and Evolutionary Biology, The University of Toronto, Toronto, ON, Canada.
Department of Biology, University of North Carolina, Chapel Hill, NC, United States.
Evolution. 2024 May 1;78(5):879-893. doi: 10.1093/evolut/qpae016.
Plants exhibit diverse breeding systems, with populations capable of outcrossing, selfing, and/or asexual reproduction. However, interactions between the three reproductive pathways remain not fully clear. Sexual reproduction introduces segregation and recombination, but incurs several costs. Selfing can affect the relative costs and benefits of sexual vs. asexual reproduction. Building population genetic models, I explore how selfing affects the evolution of a sexual reproduction rate modifier via (a) indirect selection due to segregation, (b) indirect selection from changes in recombination rates, and (c) selection from the cost of meiosis and mate limitation. The dominant selective force mediating the evolution of sex is found to vary with the rate of sexual reproduction and selfing, but selective force (a) and (c) are generally stronger than selective force (b). A modifier enhancing sexual reproduction tends to be favored by indirect selection generated by partially recessive, small-effect deleterious mutations, while hindered by highly recessive lethal mutations. Overall, evolution toward higher sexual reproduction is hindered at low sexual reproduction rates and intermediate selfing rates, but favored under high selfing rates. The results suggest that asexual reproduction may precede the evolution of selfing and offer insights into the evolution of mechanisms reducing geitonogamy in partially clonal populations.
植物表现出多样化的繁殖系统，其种群能够进行异交、自交和/或无性繁殖。然而，三种繁殖途径之间的相互作用仍不完全清楚。有性繁殖会引入分离和重组，但会带来一些成本。自交会影响有性繁殖与无性繁殖的相对成本和收益。通过构建种群遗传模型，我探讨了自交如何通过（a）由于分离导致的间接选择、（b）重组率变化的间接选择和（c）减数分裂和配偶限制的成本选择来影响性生殖率修饰因子的进化。介导性繁殖进化的主要选择力随有性繁殖和自交率的变化而变化，但选择力（a）和（c）通常比选择力（b）更强。增强有性繁殖的修饰因子往往会受到部分隐性、小效应有害突变产生的间接选择的青睐，而受到高度隐性致死突变的阻碍。总的来说，在低有性繁殖率和中等自交率下，向更高有性繁殖的进化受到阻碍，但在高自交率下则受到青睐。研究结果表明，无性繁殖可能先于自交的进化，并为部分克隆种群中减少同系交配机制的进化提供了见解。
