Testing Mechanistic Models to Explain How Variation in Host Susceptibility Arises and Why It Shifts Across Thermal Gradients.

气候变化导致的环境条件变化有可能改变已建立的生态相互作用，包括病原体和宿主之间的动态。因此，深入了解驱动宿主-病原菌动态变化的机制以及环境条件对这些机制的影响，对于预测和准备未来环境变化的影响至关重要。这项工作测试了关于温度影响太平洋鲱鱼病原体敏感性的一般机制的新假设，太平洋鲱鱼是一种具有重要生态和经济价值的海洋饲料鱼。通过将数学模型与实验室和现场收集的数据进行匹配，评估鲱鱼和适应冷水和温水的病原体在温度梯度上的反应，正在对假设进行检验。这项工作产生的基本信息增加了预测能力，以评估气候变化对宿主-病原体相互作用的长期稳定性的影响，并在基本进化过程和疾病生态之间建立联系。此外，结果使渔业管理者了解水温升高对鲱鱼家畜的影响；从而允许在鲱鱼种群评估模型中更细微地使用疾病信息，并有助于可持续的水产资源管理。除了这项研究与渔业的相关性之外，更广泛的影响集中在创建和评估多语言外展材料上，这些材料教育高中生和大学生关于气候和疾病如何相互作用影响农业和野生动物物种。研究人员还开发了一个简单的交互式网络应用程序，供管理人员探索该模型。宿主人群的易感性分布决定了短期和长期的流行特征。然而，人们对产生磁化率变化的机制知之甚少，目前的理论假设磁化率的分布在不同的环境条件下是固定的。因此，我们理解和预测气候变化下的流行病后果的能力是有限的。这一建议的中心假设试图通过假设病原体敏感性的变化作为一个随机过程来检验这一假设，该随机过程由给定温度条件下寄主和病原体特性的相对表现定义。或者，敏感性的变异可以用寄主感受性的热反应标准的遗传变异来解释。这些假说在太平洋鲱鱼中使用适应温水和冷水的病原体进行了检验，并将使用数学模型将宿主内的感染动力学与宿主间的传播动力学联系起来。根据实验室和野外家畜实验获得的实验数据，正在进一步审查已开发的理论。通过根据收集的数据严格测试理论，该项目提供了对导致疾病易感性变化的一般机制的见解，并量化了温度梯度在塑造易感性分布中所起的作用。因此，该项目有可能提供新的方法来评估气候变化对宿主-病原体相互作用的长期稳定性的影响。此外，通过描述敏感度和温度分布之间的相互作用，该项目确定了在气候变化下可能成为疾病缓解焦点的基本机制过程。该传染病生态和进化项目由生物海洋学计划和既定的刺激竞争研究计划(EPSCoR)联合资助。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Shifting environmental conditions resulting from climate change have the potential to alter established ecological interactions, including the dynamics between pathogens and hosts. As a result, developing a thorough understanding of both the mechanisms that drive host-pathogen dynamics and the influence of environmental conditions on these mechanisms is of paramount importance to predicting and preparing for the effects of future environmental change. This work tests novel hypotheses about the general mechanisms by which temperature influences pathogen susceptibility in Pacific herring, an ecologically and economically important marine forage fish. Hypotheses are being tested by fitting mathematical models to laboratory and field-collected data that evaluate the responses of herring and cold- and warm-water adapted pathogens across thermal gradients. The foundational information resulting from this work increases predictive capacities to assess the effects of a changing climate on the long-term stability of host-pathogen interactions and to build links between fundamental evolutionary processes and disease ecology. Further, results inform fisheries managers about impacts of increased water temperatures on herring epizootics; thereby allowing for a more nuanced use of disease information in herring stock assessment models and contributing to sustainable aquatic resource management. Beyond the study’s relevance to fisheries, the broader impacts focus on creating and evaluating multi-lingual outreach materials that educate high school and university students on how climate and disease interact to affect agricultural and wildlife species. The investigators are also developing a simple, interactive web application for managers to explore the model.The distribution of susceptibility in a host population determines short- and long-term epidemic characteristics. However, little is known about the mechanisms that generate variation in susceptibility, and current theory assumes that the distribution of susceptibility is fixed across environmental conditions. Our capacity to understand and predict epidemic outcomes under climate change is therefore limited. The central hypothesis of this proposal seeks to test this assumption by positing that the variation in pathogen susceptibility arises as a stochastic process defined by the relative performance of host and pathogen traits under a given temperature condition. Alternatively, variation in susceptibility may be explained by genetic variation in the thermal reaction norms of host susceptibility. These hypotheses are tested using warm- and cold-water adapted pathogens in Pacific herring and will involve the use of mathematical models to link the within-host infection dynamics to among-host transmission dynamics. Developed theory is being further scrutinized against experimental data obtained from laboratory and field epizootic experiments. By rigorously testing theory against collected data, this project provides insights into general mechanisms that generate variation in disease susceptibility and quantifies the roles that thermal gradients play in shaping susceptibility distributions. As a result, this project has the potential to provide new approaches to assess the consequences of a changing climate on the long-term stability of host-pathogen interactions. Furthermore, by describing the interplay between the distribution of susceptibility and temperature, this project identifies basic mechanistic processes that could be the foci of disease mitigation under climate change.This Ecology and Evolution of Infectious Diseases project is jointly funded by the Biological Oceanography Program and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.