Host-parasite population dynamics in experimental arenas

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My long-term research objective is to identify factors that affect host-parasite population dynamics in order to anticipate the consequences of control interventions. One of the challenges of understanding how parasitic organisms affect their host population is that research is done either in the field (where many factors influence the results) or in tightly controlled laboratory experiments (where conditions are far from those of the real world). To overcome this, I use 2 experimental systems where the parasite and host interact together in a semi-natural setting: (1) an ectoparasite that lives on the skin and fin of guppies and spreads through the population when fish come in contact with each other, and (2) a nematode parasite that lives in the intestine of mice and releases eggs in the faeces that hatch into larval stages that are then ingested by other mice in the population. This proposal addresses 3 questions. (1) We will compare the pattern of epidemic spread of the ectoparasite through guppy populations that are living in different concentrations of waterborne zinc. Zinc is a common pollutant, especially around aquaculture sites, and our results will indicate whether the presence of zinc is likely to increase the frequency of disease outbreaks. (2) Our second set of experiments will be used to explain why strains of mice that are genetically susceptible to the nematode parasite become more resistant to infection if the transmission rates are low, but that the genetically resistant mice don't become more resistant. In animal and human populations, control programs attempt to reduce rates of transmission, and design of these programs will benefit if we better understand the link between transmission rate and resistance to infection. (3) Finally, we will attempt to understand which biological processes take precedence when mice have limited energetic resources. We will measure how well mice grow, reproduce and maintain a functional immune response when they are malnourished and also infected with a nematode parasite. With ever expanding human activities, wild animals are increasingly stressed. Our work to understand how they handle competing demands may guide biologists as they try to better manage wild animal populations.