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

新出现的传染病的爆发越来越被认为是对野生动物种群的主要威胁。新病原体最初侵入易感宿主群体可引起疾病爆发，导致高水平的死亡率和群体规模的下降。当这种情况发生时，在疾病爆发期间，宿主和病原体群体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的进化变化。它还可以改变病原体破坏宿主的能力（毒力）。这些变化反过来又可以决定宿主种群是否能够持续存在并从疾病中恢复。 了解这些进化过程是至关重要的保护战略的发展受到威胁的物种。这个项目将检查这些过程的情况下，真菌病原体，导致疾病壶菌病的青蛙和蝾螈。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。研究人员将调查病原体和宿主（山地黄腿蛙）的进化变化模式，这些疾病入侵了加州塞拉内华达州的数百个高海拔湖泊。该项目将有助于理解传染病的作用，如壶菌病，作为自然种群进化变化的媒介。它将为州和联邦机构提供关键信息。它还将培训和教育众多的本科生和研究生以及公众。这项研究建立在对加州内华达山脉内华达州复杂景观中的山地黄腿蛙（Rana sierleum和Rana muscosa）的种群动态进行长期研究的数据基础上，以及Batrachochytrium dendrobatim（Bd）的影响，因为它已经入侵并传播到数百个青蛙种群。在大多数情况下，Bd的入侵导致壶菌病的爆发，青蛙种群的迅速下降和局部的灭绝。然而，在某些情况下，青蛙种群的长期持续性发生在Bd的地方病状态下，其中病原体的影响大大降低。这项研究将利用分子方法的最新进展，以及来自R。锡耶尔特河muscosa-Bd系统，以调查在从病原体到达前到疾病爆发，到地方病，到疾病前宿主种群丰度的潜在恢复的过渡期间，宿主和病原体的种群如何变化。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继续调查野外种群相结合，以确定新的疾病爆发，并描述从爆发到地方流行状态的转变，从野外种群收集Bd培养物和青蛙粘膜样本，并对Bd毒力和青蛙进行实验室实验。

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