Individuals, energetics and infectious disease

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Infectious diseases of wildlife are an increasing concern as global travel and trade affect pathogen dispersal, and environmental change affects host susceptibility. There is growing realization that pathogens can cause species extinctions and loss of biodiversity and growing appreciation that wildlife diseases are relevant to human public health. Most recent emerging infectious diseases of humans (e.g., SARS, Hendra, Nipah, Marburg, Ebola) appear to have arisen when wildlife, specifically bats, were forced into contact with people due to human development. In North America, hibernating bats also face an urgent conservation threat from the novel fungal disease white-nose syndrome. Despite ecological, economic, public health and conservation implications of wildlife pathogens, we have limited experimental data about host-pathogen dynamics for most wildlife diseases. Therefore, over the long-term, I aim to test a broad hypothesis with theoretical but little experimental support: behavioural and physiological variation among individuals, social groups and populations of hosts affects host-pathogen dynamics and pathogen impacts. My short-term objectives are to use social species of bats to test three predictions arising from this hypothesis: (1) At the individual-scale, personality, and energetics affect individual risk of acquiring and spreading pathogens; (2) At the scale of social groups, personality composition of groups, and environmental characteristics (e.g., habitat quality, weather, climate) affect transmission via their influence on social dynamics; and (3) At the landscape scale, population and community characteristics (e.g., host density and genetic structure, host and parasite diversity) affect pathogen dynamics and disease impacts. Two key innovations underpin this proposal. First is our potential to manipulate social dynamics, energetic state and group composition of bats experimentally in large flight enclosures to assess how attributes of individuals and groups affect rates of pathogen invasion and transmission. Importantly, I will base experimental manipulations on real-world environmental changes. For example, climate change is likely to affect energetic status and use of torpor in heterotherms and urban and industrial development are likely to alter habitat in ways that affect social dynamics. Our experiments will imitate these changes. Second, is our preparedness for the imminent invasion of a wildlife pathogen causing massive population declines. To date we have marked over 10,000 free-ranging bats with passive transponders in central Canada. We will monitor arrival and departure of these animals at 10 hibernacula across the region, providing a unique opportunity to assess the role of host and environmental characteristics on pre- and post-infection mortality for a disease of tremendous conservation significance.