We will characterize the linkage between the within-host microbial interactions and the transmission dynamics of the multi-parasite assemblage. We hypothesize that a key component of this linkage between the levels of host individuals and the host population is heterogeneity among parasite individuals.

We propose to address three major research questions.

Question 1: To what degree are epidemic dynamics driven by responses of parasite community structure to microbial interactions?

Question 2: To what degree are epidemic dynamics driven by population genetic responses of parasites to microbial interactions?

Question 3: To what degree are epidemic dynamics driven by plastic responses of individual parasites to microbial interactions?

To answer our research questions, we will conduct two major field activities, an observational survey and a manipulative experiment. Each of these activities will be used to answer at least two research questions, so for simplicity we here outline the general approaches in common across questions. In addition to these two major field activities, we will also conduct several other experiments and surveys that are more limited in scope, each of which is detailed under the question that it will answer.