1] College of Life Science and State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, Shaanxi, China [2] Bioinformatics Center, Northwest A&F University, Yangling, Shaanxi, China.
Heredity (Edinb). 2013 Dec;111(6):505-12. doi: 10.1038/hdy.2013.72. Epub 2013 Jul 31.
The mechanism of reproducing more viable offspring in response to selection is a major factor influencing the advantages of sex. In diploids, sexual reproduction combines genotype by recombination and segregation. Theoretical studies of sexual reproduction have investigated the advantage of recombination in haploids. However, the potential advantage of segregation in diploids is less studied. This study aimed to quantify the relative contribution of recombination and segregation to the evolution of sex in finite diploids by using multilocus simulations. The mean fitness of a sexually or asexually reproduced population was calculated to describe the long-term effects of sex. The evolutionary fate of a sex or recombination modifier was also monitored to investigate the short-term effects of sex. Two different scenarios of mutations were considered: (1) only deleterious mutations were present and (2) a combination of deleterious and beneficial mutations. Results showed that the combined effects of segregation and recombination strongly contributed to the evolution of sex in diploids. If deleterious mutations were only present, segregation efficiently slowed down the speed of Muller's ratchet. As the recombination level was increased, the accumulation of deleterious mutations was totally inhibited and recombination substantially contributed to the evolution of sex. The presence of beneficial mutations evidently increased the fixation rate of a recombination modifier. We also observed that the twofold cost of sex was easily to overcome in diploids if a sex modifier caused a moderate frequency of sex.
为了应对自然选择而产生更多有活力后代的机制是影响性别的主要因素。在二倍体中，有性生殖通过重组和分离来组合基因型。有性生殖的理论研究已经调查了单倍体中重组的优势。然而，对二倍体中分离的潜在优势的研究较少。本研究旨在通过多点模拟来量化重组和分离对有限二倍体中性进化的相对贡献。通过计算有性或无性繁殖群体的平均适合度来描述性的长期影响。还监测了性或重组修饰体的进化命运，以研究性的短期影响。考虑了两种不同的突变情景：(1)仅存在有害突变，(2)有害和有益突变的组合。结果表明，分离和重组的综合作用强烈促进了二倍体中性的进化。如果仅存在有害突变，分离有效地减缓了 Muller 的棘轮的速度。随着重组水平的增加，有害突变的积累完全被抑制，重组对性的进化做出了重大贡献。有益突变的存在明显增加了重组修饰体的固定率。我们还观察到，如果性修饰体导致适度的性发生频率，那么二倍体中两倍的性成本很容易克服。
