| Sperm competition is a powerful selective force in nature. Post-copulatory interactions between male ejaculates, and ejaculates and females, influence a variety of reproductive processes with important consequences for the fitness of both sexes. There is a considerable amount of evidence suggesting that both sperm and non-sperm elements in ejaculates are important in mediating many of these effects. Seminal substances transferred during copulation can play an important role in stimulating female responses, sustaining stored sperm and affecting male fertilization success. In spite of this, models of sperm competition have generally focused only on the sperm-containing portion of the ejaculate. Furthermore, although a considerable amount of attention has recently been paid to male seminal substances, we still know relatively little about the extent of standing genetic variance in many of these reproductive proteins and almost nothing about their effects on the predictions of sperm competition models. Both the theory and experiments described in this thesis explore the role of ejaculate characters in post-copulatory interaction. (Abstract shortened by UMI.)... |
