Dissertation Research: Genetic and Environmental Mechanisms Mediating Disease Resistance and Tolerance in Amphibians

确定在野外反复爆发传染病的原因对于了解人类和生态系统健康至关重要。环境变化可能会降低宿主进化抗性的能力或保持在其耐受范围内，从而使病原体更有可能导致疾病和死亡。该项目调查热带两栖动物感染的季节性变化模式，并测试以下假设：疾病模式是对病原体具有遗传抗性的个体频率变化的结果，或者是环境压力导致的宿主条件减弱的结果。缺乏遗传决定因素的青蛙也可能依赖环境调节剂(例如共生细菌)来减轻病原体的损害。这些免疫策略如何以及何时相互作用，使两栖动物能够坚持新出现的疾病，目前尚不清楚。利用波多黎各下降的青蛙种群在感染动态中表现出高度的异质性和季节性，PI结合了种群基因组学和元基因组学来确定环境和宿主的适应性反应如何影响疾病的结果。两栖动物数量减少的话题及其对环境健康的影响已经引起了公众的关注；因此，这个项目为非科学家提供了一个很好的机会来教育他们关于遗传学、免疫学和疾病生态学的知识。两家私人投资机构都通过媒体、教育宣传和非政府组织向普通受众传播他们的科学发现。此外，该项目吸引了来自少数族裔的学生和研究人员，促进了美国和波多黎各机构之间的合作，并增加了对生态、进化和保护感兴趣的学生的多样性。这些结果可以被保护机构用于物种优先计划和圈养繁殖计划。

Identifying the causes of recurrent outbreaks of infectious diseases in the wild is critical to understanding human and ecosystem health. Environmental change may reduce the ability of hosts to evolve resistance or persist within their tolerance limits, thus making pathogens more likely to cause disease and mortality. This project investigates seasonally variable patterns of infection in tropical amphibians and tests the hypotheses that disease patterns are a consequence of changes in the frequency of individuals that have genetically-based resistance to the pathogen, or alternatively, a result of a weakened host condition caused by environmental stress. Frogs lacking genetic determinants may also rely on environmental modulators (e.g., symbiotic bacteria) to alleviate pathogen damage. How and when these immune strategies interact to allow amphibians to persist emergent diseases is unknown. Using declining frog populations in Puerto Rico that exhibit high heterogeneity and seasonality in infection dynamics, the PIs combine population genomics and metagenomics to determine how environmental and host adaptive responses affect the outcome of disease. The topic of amphibian declines, and its implications for environmental health, has reached public awareness; thus this project offers an excellent opportunity to educate non-scientists about genetics, immunity, and disease ecology. Both PIs disseminate their scientific findings to general audiences through media, educational outreach, and NGOs. In addition, the project involves students and researchers from underrepresented minorities, fosters collaborations between USA and Puerto Rican institutions, and increases diversity among students interested in ecology, evolution, and conservation. These results can be used by conservation agencies in species prioritization schemes and captive breeding programs.