Mutation load is a key parameter in evolutionary theories, but relatively little empirical information exists on the mutation load of populations, or the elimination of this load through selection. We manipulated the opportunity for sexual selection within a mutation accumulation divergence experiment to determine how sexual selection on males affected the accumulation of mutations contributing to sexual and non-sexual fitness. Sexual selection prevented the accumulation of mutations affecting male mating success, the target trait, as well as reducing mutation load on productivity, a non-sexual fitness component. Mutational correlations between mating success and productivity (estimated in the absence of sexual selection) were positive. Sexual selection significantly reduced these fitness component correlations. Male mating success significantly diverged between sexual selection treatments, consistent with the fixation of genetic differences. However, the rank of the treatments was not consistent across assays, indicating that the mutational effects on mating success were conditional on biotic and abiotic context. Our experiment suggests that greater insight into the genetic targets of natural and sexual selection can be gained by focusing on mutational rather than standing genetic variation, and on the behavior of trait variances rather than means.
Female harm viability data
This data is associated with the supplementary results, and file was created in Excel. It is the count of individual adults (M=males; F=females) emerging from single pair matings. Females from Control MA lines (not subjected to sexual selection) were paired with random males from either Control or Selection MA lines. Approximately 20 females per MA line were mated with males from the Selection treatment and 20 with males from the Control treatment. Male treatment (C=Control; S=Selection) is recorded. Approximately 10 males per MA line were assayed (MaleMALine, with numbers nested within Treatment). The mating pairs were set-up over 3 days.
Viability data
This data is the count of the number of individual adults (M=Male; F=Female) emerging from single brother-sister mating pairs. These pairs came from different selection treatments (C=Control; S=Selection), with individual MA lines nested within treatment. File was created in Excel.
Male Mating Success
This data file was created in Excel. It is the mating success of males in assays in generations 1, 3, 7, 11 and 23 of a mutation accumulation experiment in which one set of 100 lines were subjected to sexual selection on male mating success (Treatment = S) and the other set of 100 lines were not (Treatment = C; Controls). Except in generation 1, C and S males were competed against one another, and half of the assayed males per line had their wings clipped for identification (Clip = 1; males without clip, Clip=0). Trials were conducted over 2 days each generation. The choosing female in these trials came from the stock population. Males were either successful in gaining a mating (choice=1) or unsuccessful (choice=0).
Gen 20 male mating success
This data file was created in Excel. It is the mating success of males assayed in generation 20, where females from the MA lines choose between a stock male and a male from a MA line. MA lines were divided into two treatments: Controls (C), without sexual selection and Selection (S) with sexual selection. Trials were conducted over 2 days. . Males were either successful in gaining a mating (choice=1) or unsuccessful (choice=0).