LTREB : Collaborative Research: Long-term dynamics of amphibian populations following disease-driven declines

新出现的传染病的爆发日益被认为是对野生动物种群的主要威胁。一种新型病原体最初侵入易感宿主种群可引起疾病暴发，导致高死亡率和种群规模下降。当这种情况发生时，在疾病爆发期间，宿主和病原体种群都可能发生自然选择。这可能导致宿主对病原体感染的易感性和耐受性发生进化变化。它还可以改变病原体破坏宿主的能力（毒力）。这些变化可反过来决定宿主种群能否持续存在并从疾病中恢复。了解这些进化过程对于制定保护濒危物种的策略至关重要。这个项目将检查这些过程的真菌病原体的情况下，导致疾病壶菌病在青蛙和蝾螈。这种疾病对全世界的两栖动物造成了灾难性的影响，近几十年来记录了许多物种的灭绝，还有更多的物种处于危险之中。在这种疾病侵入加州内华达山脉的数百个高海拔湖泊之后，研究人员将调查病原体和宿主（山黄腿蛙）的进化变化模式。这个项目将有助于了解诸如壶菌病等传染病作为自然种群进化变化的媒介的作用。它将为州和联邦机构提供关键信息。它还将培养和教育大量的本科生和研究生以及公众。这项研究建立在对加利福尼亚内华达山脉复杂景观中山黄腿蛙（Rana sierrae和Rana muscosa）种群动态的长期研究数据的基础上，以及Batrachochytrium dendroatidis （Bd）的影响，因为它已经入侵并传播到数百个青蛙种群中。在大多数情况下，Bd的入侵导致壶菌病的爆发，青蛙数量迅速下降和局部灭绝。然而，在某些情况下，蛙种群的长期持续存在发生在一种地方病状态下，在这种状态下病原体的影响大大降低。该研究将利用分子方法的最新进展，以及来自R. sierra /R.的广泛数据集和样本档案。研究宿主和病原体种群在从病原体到来前到疾病爆发、到地方病、到疾病前宿主种群丰度可能恢复的过渡过程中是如何变化的。该数据集将用于研究宿主抗性/耐受性和病原体毒力差异的遗传基础。现有拭子样本的尖端基因组分析将与对野外种群的持续调查相结合，以确定新的疾病暴发并描述从暴发到地方性动物疾病状态的转变，收集野外种群的Bd培养物和青蛙粘膜样本，以及对Bd毒力和青蛙的实验室实验

Outbreaks of emerging infectious diseases are increasingly recognized as major threats to wildlife populations. The initial invasion of a novel pathogen into a susceptible host population can cause a disease outbreak resulting in high levels of mortality and declines in population size. When this happens, natural selection can occur on both the host and pathogen populations during the disease outbreak. This can result in evolutionary changes in the host's susceptibility and tolerance to infection by the pathogen. It can also change the pathogen's ability to damage the host (virulence). These changes can in turn determine whether the host population can persist and recover from the disease. Understanding these evolutionary processes is crucial in development of conservation strategies for threatened species. This project will examine these processes for the case of a fungal pathogen that causes the disease Chytridiomycosis in frogs and salamanders. This disease has had catastrophic effects on amphibians worldwide, with numerous species extinctions documented in recent decades and many more species at risk. The researchers will investigate the patterns of evolutionary change in both the pathogen and the host (mountain yellow-legged frogs), following the invasion of the disease into hundreds of high elevation lakes in the California Sierra Nevada. This project will contribute to the understanding of the role of infectious diseases, such as Chytridiomycosis, as agents of evolutionary change in natural populations. It will provide critical information to state and federal agencies. It will also train and educate numerous, undergraduates and graduate students as well as the general public. This research builds on data from a long-term study of the population dynamics of mountain yellow-legged frogs (Rana sierrae and Rana muscosa) in the complex landscape of the California Sierra Nevada, and the impacts of Batrachochytrium dendrobatidis (Bd), as it has invaded and spread through hundreds of frog populations. In most cases, invasion of Bd results in outbreaks of the disease Chytridiomycosis, rapid frog population declines, and local extinctions. In some cases however long-term persistence of frog populations occurs with Bd in an enzootic state in which the impact of the pathogen is greatly reduced. The research will make use of recent advances in molecular approaches, and the extensive dataset and archive of samples from the R. sierrae/R. muscosa - Bd system, to investigate how populations of both host and pathogen change during the transition from pre-pathogen arrival, to disease outbreak, to enzootic disease, to potential recovery of the pre-disease host population abundances. This dataset will be used to investigate the genetic basis for differences in host resistance/tolerance and pathogen virulence. Cutting-edge genomic analysis of existing swab samples will be combined with continued surveys of field populations to identify new disease outbreaks and describe the transition from outbreak to enzootic state, collection of Bd cultures and frog mucosal samples from field populations, and laboratory experiments on Bd virulence and frog