Symposium: Insect Behavioral Ecology--85: Prezygotic Male Reproductive Effort in Insects: Why do Males Provide More Than Sperm?

Abstract

Males' incentives for providing benefits to females and/or their offspring are ambiguous during the period prior to zygote formation. The benefits may function to increase the number of available eggs fertilized by a male and/or enhance the production and survival of his offspring. In some cases, male prezygotic investment may be an adaptation to secure fertilizations despite the fact that it incidentally benefits the female or her offspring. More often, the benefits to offspring production and survival are not simply incidental and probably account, in part, for the magnitude of the male investment. Regardless of the adaptive significance of male provided benefits, they typically reduce the females' costs of producing surviving offspring while raising the males' costs. The extent to which provisioning of benefits increases males' costs and decreases females' costs will affect the degree to which females limit male reproduction (or vice versa). If male-provided benefits (prezygotic or otherwise) are more costly than female costs of offspring production, reproductively-ready males will act as resources limiting female reproduction. From an evolutionary perspective it is important to consider the effect of male-provided benefits. The primary function of the investment (e.g., to maximize sperm transfer) is irrelevant in terms of the degree to which one sex limits the other's reproduction.