Mating with a large male yellow dung fly: costs or benefits in terms of clutch size?

Abstract

Mating, and mate choice, typically carry benefits as well as costs for the female, which can be manifested in certain fitness components but not others. Both fecundity benefits and costs have been reported in some speciesfor females that mate with larger males. The former has been interpreted as cryptic female choice, whereas the latter indicates sexual conflict. Using four independent data sets, we examined whether female clutch size varies with the size of her mate in the yellow dung fly Scathophaga stercoraria, a classic model species for studies of sexual selection and conflict. We found that clutch size depends strongly on female size but not male size, revealing neither costs nor benefits. It is possible that female dung flies are constrained in modifying their clutch size, or that this sort of strategic oviposition does not pay in this species. We suggest that mating costs or benefits in terms of fecundity may be relatively rare compared with corresponding effects on survivorship.