Strategic male mate choice minimizes ejaculate consumption

Reproduction can be costly for males, particularly when they provide nutrient-rich ejaculates in the form of spermatophores or secondary ejaculatory components. These costs may further increase if females reject or consume a male’s ejaculate rather than using it for egg fertilization. Males should, therefore, attempt to minimize these costs to maximize their reproductive payoffs. We examined male reproductive investment toward virgin females in the Southern Bottletail Squid, Sepiadarium austrinum. Specifically, we assessed whether the presence of unfertilized eggs inside females influenced male reproductive investment, whether females removed spermatophores postcopulation, and what phenotypic characteristics influenced spermatophore removal. We found that males were more likely to attempt mating with females that were proportionally larger, but mated for longer and were more likely to transfer spermatophores to egg-carrying females. Females consistently ate spermatophores transferred by males, with the smallest females eating the most. However, males did not vary spermatophore investment according to female size or the associated risk of spermatophore consumption.