Impacts of Infections and Predation on Dynamics of Sexually Reproducing Populations

Although sexual reproduction is ubiquitous, population models are commonly formulated as asexual. The major arguments behind this conceptual simplification are two: females are always able to secure a male for reproduction or both sexes share common life history. Whereas the first argument fails when females have increasing difficulty to mate when population density declines, the second argument does not apply when predators attack female and male prey at different rates. But even if both sexes share common life history, the conventional population models and models that start with explicit mating dynamics may eventually differ, and produce different predictions. Here I present some of my previous work to show how sexually transmitted infections and sex-specific predation may modify dynamics predicted by conventional asexual models. I start with sex-structured population models that I extend to include infections and predation, claiming that this practice can take one to a properly formulated population model, whether sexual or asexual.