Parasite-Mediated Competition: A Model of Directly Transmitted Macroparasites

Abstract

There is growing interest in host-parasite ecology, particularly with regard to the effect of parasites on host community structure, but few studies have explored the theory of parasite mediation of host competition. I developed a model to examine the impact of directly transmitted macroparasites on the competition and population dynamics of two sympatric host species. Several important features of macroparasite-mediated competition are considered in the model: the two host species compete in a classical Lotka-Volterra manner, the parasite influences the survivorship and reproduction of both hosts, and parasites exhibit aggregated distribution among host populations. The conditions for host coexistence were derived explicitly. The results suggest that host intrinsic growth rate, host carrying capacity, susceptibility, parasite pathogenicity, and the magnitude of parasite aggregation are important components influencing host coexistence. Parasites may enhance or disrupt host coexistence, depending on the r...