The cost of mating rises nonlinearly with copulation frequency in a laboratory population of Drosophila melanogaster

Abstract

Previous studies of Drosophila melanogaster have demonstrated a cost to females from male courtship and mating, but two critically important parameters remain unresolved: (i) the degree to which harm from multiple‐mating reduces lifetime fitness and (ii) how harm from mating might change with successive matings (rematings). Here we use ‘laboratory island analysis’ to quantify the costs that females incur with each remating, in the currency of lifetime fitness and under conditions that closely match those to which the flies have adapted for hundreds of generations. We experimentally manipulated the number of female matings by varying the order of daily 2‐h exposures of females to either sperm‐less males (XO) or intact males (XY). Females that mated more often had substantially reduced lifetime fecundity, and importantly, the fitness cost from remating rapidly accelerated.

Interactive effects of sex, social environment, dietary restriction, and methionine on survival and reproduction in fruit flies

“…This tradeoff was largely unaffected by social environment in females. Female fruit flies in the two social environments differed in the mean of their survival and reproductive fitness response across all diets, with females in separate-sex groups having higher survival and reproductive fitness, compared to females in mixed-sex groups (corroborating previous findings; Kuijper et al 2006), but there were no interactions between the effects of social environment and diet. Our data thus suggest that fecundity and lifespan patterns from studies of aging using similar experimental diets, conducted on once-mated female flies kept without males, would not differ fundamentally from the results gained from females in mixed-sex groups, when patterns of dietdependent survival and fecundity are concerned.…”

Direct observation of female mating frequency using time-lapse photography

“…Thus, our data suggests that not only is the opportunity for postcopulatory processes of sexual selection in the laboratory environment comparable with that found in natural populations of D. melanogaster, but that female resistance to mating approximately doubles with each additional mating. This latter result is particularly interesting given that it is known that mating costs for females also rise (nonlinearly) with each additional mating, 22 suggesting either that part of these costs may derive from increases in the level of female behavioral resistance to male advances, or that female reluctance to remate is due in part to these accelerating costs. An alternative explanation is that the increasing mating interval is due to an increase in male (or female) reluctance to remate the same partner, a phenomenon known as the Coolidge effect.…”

Proteomics enhances evolutionary and functional analysis of reproductive proteins

“…Nonetheless, sexual conflict may be an important diversifying force in many situations, given the prevalence of documented conflicts in model systems. (85,86,90,91) Appealingly, the hypothesis does not depend on external factors, such as the presence of related species or pathogens, to explain rapid evolution in non-monogamous mating systems. However, measurements of the costs and benefits accrued by each sex during mating are necessary to assess the opportunities for conflict.…”

“…(58,77,83) Under sexual conflict, males and females have different optima for a particular reproductive trait, and the rapid coevolution of reproductive proteins may represent each sex's effort to achieve its own optimum, at a fitness cost to the opposite sex. (65,(84)(85)(86)(87) Another hypothesis is selection that reinforces against hybrid formation. Reinforcement operates when two species occupying the same area interbreed, and the resulting hybrids have reduced fitness.…”