Local adaptations to infectious diseases: curse or opportunity?

传染病在人类和野生动物中普遍存在。然而，毒力、流行、耐受性和耐药性的模式并不独特，往往依赖于环境，这使得对传播和潜在缓解的预测都成为一项挑战。我的研究计划的长期目标是在广泛的地理范围内评估疾病相关特征的变化，并揭示使我们对传染病及其在当地灭绝中的作用的理解复杂化的多种因素。在这种情况下，两栖动物是一个理想的模型，因为它们分布广泛，越来越多的证据表明，它们正面临全球衰退，近10%的两栖动物种群接近灭绝，另有32%的两栖动物被列为受威胁物种。此外，它们代表了一个非常好的研究系统，可以调查生态和进化过程之间的联系以及对调节宿主-寄生虫共同进化结果的机制的理解。在北美，林蛙（Rana sylvatica）和北豹蛙（Rana pipiens）是受一种病毒（Ranavirus）和一种壶菌（Batrachochytrium dendroatidis）影响的广泛物种，我将利用这两种宿主物种的现有种群网络，在从田纳西州到西北地区的纬度梯度上，研究它们对这些病原体的反应。

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.