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

A proposed benefit to sexual selection is that it promotes purging of
deleterious mutations from populations. For this benefit to be realised,
sexual selection, which is usually stronger on males, must purge mutations
deleterious to both sexes. Here, we experimentally test the hypothesis
that sexual selection on males purges deleterious mutations that affect
both male and female fitness. We measured male and female fitness in two
panels of spontaneous mutation-accumulation lines of the fly, Drosophila
serrata, each established from a common ancestor. One panel of mutation
accumulation lines limited both natural and sexual selection (LS lines),
whereas the other panel limited natural selection, but allowed sexual
selection to operate (SS lines). Although mutation accumulation caused a
significant reduction in male and female fitness in both the LS and SS
lines, sexual selection had no detectable effect on the extent of the
fitness reduction. Similarly, despite evidence of mutational variance for
fitness in males and females of both treatments, sexual selection had no
significant impact on the amount of mutational genetic variance for
fitness. However, sexual selection did reshape the between-sex correlation
for fitness: significantly strengthening it in the SS lines. After 25
generations, the between-sex correlation for fitness was positive but
considerably less than one in the LS lines, suggesting that, although most
mutations had sexually concordant fitness effects, sex-limited and/or
sex-biased mutations contributed substantially to the mutational variance.
In the SS lines this correlation was strong and could not be distinguished
from unity. Individual-based simulations that mimick the experimental
setup reveal two conditions that may drive our results: (1) a
modest-to-large fraction of mutations have sex-limited (or highly
sex-biased) fitness effects, and (2) the average fitness effect of
sex-limited mutations is larger than the average fitness effect of
mutations that affect both sexes similarly.

性选择的一个潜在益处在于它能促进种群中有害突变（deleterious mutations）的清除。若要实现这一益处，通常对雄性作用更强的性选择必须清除对雌雄两性均有害的突变。在此，我们通过实验验证如下假说：对雄性的性选择可清除影响雌雄两性适合度（fitness）的有害突变。我们测定了锯齿状果蝇（Drosophila serrata）两个自发突变累积品系组（spontaneous mutation-accumulation line panels）的雌雄适合度，每组品系均源自同一祖先。其中一组突变累积品系限制了自然选择与性选择（LS品系），另一组则仅限制自然选择，允许性选择发挥作用（SS品系）。尽管突变累积导致LS与SS品系的雌雄适合度均显著降低，但性选择对适合度降低的程度无显著影响。类似地，尽管两种处理下的雌雄个体均存在适合度的突变方差（mutational variance），但性选择对适合度的突变遗传方差（mutational genetic variance）量无显著影响。然而，性选择确实重塑了适合度的性别间相关性：在SS品系中显著增强了该相关性。经过25代后，LS品系中适合度的性别间相关性为正但远低于1，这表明尽管大多数突变具有性别一致的适合度效应，但限性突变（sex-limited mutations）和/或性偏向突变（sex-biased mutations）对突变方差的贡献显著。模拟实验设计的基于个体的模拟（individual-based simulations）结果揭示了可能导致上述结果的两个条件：（1）中等至较大比例的突变具有限性（或高度性偏向）适合度效应；（2）限性突变的平均适合度效应大于对雌雄两性影响相似的突变的平均适合度效应。