Data from: Sexual selection on spontaneous mutations strengthens the between-sex genetic correlation for fitness

One hypothesised benefit to sexual selection is that it reduces mutation load. Here, we experimentally tested this idea, assaying male and female fitness in an experiment previously conducted on the fly, Drosophila serrata, where two panels of spontaneous accumulation lines were established from a common ancestor. In one panel, both natural and sexual selection were limited (LS), and in the other sexual selection was allowed to operate while natural selection was limited (SS). The effects of the sexual selection treatment were surprising. Although mutation accumulation reduced male and female fitness in both sets of lines, sexual selection had no detectable effect on the extent of fitness reduction or the amount of mutational variance for fitness in either sex. Sexual selection did however reshape the between-sex correlation for fitness, rM(m,f); significantly strengthening it. After 25 generations, rM(m,f) was positive but considerably less than one in the LS lines, suggesting although most mutations had sexually concordant fitness effects, sex-limited and/or sex-biased mutations also accumulated. In the SS lines rM(m,f) was strong and could not be distinguished from one. Simulations of the experimental setup revealed that this result may be due to sexual selection targeting relatively large effect mutations with male-limited fitness effects.有假说指出，性选择（sexual selection）的一项潜在益处是能够降低突变负荷（mutation load）。本研究通过实验验证了这一假说，我们对此前以锯果蝇（Drosophila serrata）为研究对象的实验中的雌雄适合度（fitness）进行了测定：该实验以一个共同祖先为起始，构建了两组自发突变积累品系（spontaneous accumulation lines）。其中一组同时限制了自然选择（natural selection）与性选择，记为LS组；另一组则允许性选择发挥作用，同时限制自然选择，记为SS组。性选择处理所带来的效应出人意料。尽管突变积累在两组品系中均降低了雌雄个体的适合度，但性选择并未对雌雄个体的适合度降低幅度，或是适合度相关的突变方差（mutational variance）产生可检测到的影响。不过，性选择确实重塑了雌雄适合度间的相关系数（r_M(m,f)），使其显著增强。在历经25代培养后，LS组中的r_M(m,f)为正值，但显著小于1，这表明尽管多数突变具有性别一致的适合度效应，但性别限制型和/或性别偏倚型突变也发生了积累。而在SS组中，r_M(m,f)数值极高，与1无显著差异。对实验设置的模拟分析显示，这一结果可能源于性选择靶向作用于那些具有雄性限制型适合度效应的大效应突变。