Effects of Host Sexual Selection on the Population Biology of Parasites

Parasites have been hypothesized to play an important role in sexual selection of their hosts, and a considerable body of evidence supports parasite-mediated sexual selection. However, there has hardly been any emphasis on the effects of host sexual selection on the ecology and evolution of parasites. Coevolution between hosts and parasites r..ay result in important differences between parasites exploiting more and less sexually selected hosts. I suggest that parasites of intensely sexually selected hosts should affect a small proportion of hosts with intensities being more skewed than among hosts that are less sexually selected. Intraand intersexual interactions among hosts give rise to ample opportunities for horizontal transmission and hence select for increased virulence. Rapid coevolution between parasites and their hosts should select for increased host specificity among parasites of highly sexually selected hosts. Sexual selection has been hypothesized to play an important role in speciation, and rapid divergence among hosts may also result in rapid divergence among host-specific parasites.