Local adaptations to infectious diseases: curse or opportunity?

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Infectious diseases are prevalent worldwide in humans and wildlife. Yet, patterns of virulence, prevalence, tolerance, and resistance are not unique, often environment-dependent and make both predictions regarding spread and potential mitigations a challenge. The long-term goal of my Research Program is to assess variation in disease-related traits across a wide geographic range and uncover the multiple factors that complicate our understanding of infectious diseases and their role in local extinctions. In this context, Amphibians are an ideal model as they are widely distributed and increasing evidence suggests that they are facing global declines with nearly 10% of the populations of all amphibian species close to extinction and a further 32% classified as threatened. Additionally, they represent a very good study system to investigate questions around the links between ecological and evolutionary processes and the understanding of mechanisms that modulate host-parasite coevolutionary outcomes. In North-America, the Wood frog, Rana sylvatica, and the Northern Leopard frog, Rana pipiens, are widespread species affected by a virus (Ranavirus) and a chytrid fungus (Batrachochytrium dendrobatidis) and I will investigate the responses to these pathogens across the host geographic ranges, using an existing network of populations from these two host species across a latitudinal gradient spanning from Tennessee to the Northwest-Territories.***Using a combination of field and lab-based observations and experiments and considering the current knowledge on host-parasite evolutionary ecology, my short-term objectives for this five year grant cycle will be addressed through the following questions:******1. How does environmental heterogeneity modulate the host-pathogen interactions, and how this may affect frog population dynamics?***2. Is variation in the host phenotype associated with infection levels and how this may reflect local adaptation to pathogens? ***3. How does the variation in pathogen genotype shape local adaptation of frog populations? ******Whether hosts have been and will continue to adapt to these fast-evolving pathogens, or be under the considerable threat associated with an overall change in their environment, including pandemics remains an important question in evolutionary ecology. Ultimately, the results from this research will help reaching my long-term objectives to develop a theoretical and empirical framework for a better understanding of infectious diseases in wildlife as well as provide epidemiological tools for the conservation of wildlife.