Sex ratio at mating does not modulate age fitness effects in D. melanogaster

Understanding the effects of male and female age on reproductive success is vital to explain the evolution of life history traits and sex-specific ageing. A general prediction is that pre/post-meiotic ageing processes will lead to a decline in the pre- and post-copulatory abilities of both males and females. However, inasmuch as sexes have different strategies to optimize their fitness, the decline of reproductive success late in life can be modulated by social context, such as sex ratio, in a sex-specific manner. In this study, we used Drosophila melanogaster to investigate whether sex ratio at mating modulates age effects on male and female reproductive success. As expected, male and female age caused a decrease in reproductive success across male-biased and female-biased social contexts but, contrary to previous findings, social context did not modulate such age-related fitness decline in either of the two sexes. We discuss these results in the light of how sex ratio might modulate p...