Sexual Transmission of Disease and Host Mating Systems: Within-Season Reproductive Success

Abstract

While there is an extensive literature on the evolution of mating systems in animals, little consideration has been given to the possible evolutionary interactions between sexually transmitted pathogens and the mating systems of their hosts. We use individual-based models that incorporate measurable per-contact probabilities of infection and fertilization to show that not only can the presence of sexually transmitted (and sterilizing) pathogen have significant effects on optimal within-season mating strategies for both males and females. We show that, contrary to expectations, monogamy is not always predicted to be the optimal strategy. The optimal strategy may also often differ between the two sexes, and the optimal strategy will not always be the one that minimizes disease transmission. Similarly, we show that the optimal level of virulence for a sexually transmitted pathogen is a function of the degree of promiscuity of its host. Overall, these results suggest that sexually transmitted diseases can impact host mating behavior, often in nonintuitive directions.