Meeting Abstract

S4-2.1  Jan. 5  Evolutionary implications for interactions between multiple strains of hosts and parasites ZHANG, P.; SANDLAND, G.; FENG, Z.*; XU, D.; MINCHELLA, D.; Purdue University

The interaction between multiple parasite strains within different host types may influence the evolutionary trajectories of parasites. We formulate a deterministic model with two strains of parasites and two host types in order to investigate how heterogeneities in parasite virulence and host life-history may affect the persistence and spread of diseases in natural systems.The reproductive number for each strain of parasites ($mathcal R_i$) as well as the ``invasion'' reproductive number for strains $i$ ($R_i^j$, $jneq i$) are computed and shown to determine the stability of various equilibria. We show that strain $i$ can invade strain $j$ when $mathcal R_i^j>1$. Subthreshold coexistence driven by co-infection is possible even when ${mathcal R}_i$ of one strain is below 1. Conditions are identified that determine the evolution of parasite specialism or generalism based on the life-history strategies employed by hosts, and investigate how host strains may influence parasite persistence.