Coevolution and Local Adaptation in a Salamander-Virus System

传染病日益被认为是21世纪的主要健康挑战，并对生物多样性产生重大影响。疾病-宿主系统令人着迷的复杂性推动了共同进化，因为宿主始终面临进化防御的压力，病原体需要进化出新的方法来逃避它们。这个项目将采用一种实验方法来测试三个问题，这些问题对于在使用老虎火蜥蜴和一种新出现的病毒的模型系统中理解宿主和病原体的共同进化是基本的。首先，病原体是在当地适应的吗？病原体在本地宿主上的表现可能比外国宿主更好，因为病原体通常进化得更快。第二，病原体应该如何影响新的寄主物种？也许是因为病原体在当地适应了当地的宿主，所以它们在幼稚物种上的表现就不会那么好。或者，新的病原体可能表现良好，因为幼稚的宿主没有进化出防御系统。第三，东道主是否适应当地的情况？寄主的遗传变异性将被直接操纵，应该在抗病中发挥关键作用。这项工作的更广泛影响是巨大的，因为如果病原体在当地适应，那么在一个宿主群体中开发的潜在治疗方法可能对另一个宿主群体无效。此外，由于病原体的全球传播可能在几天内发生(如SARS)，并可能发生生物恐怖主义，因此模型系统的研究对于了解病原体对新宿主的影响至关重要。了解病原体对新寄主物种的影响可以导致对病原体传播和疾病出现的预测。此外，病原体与全球两栖动物的减少有关，从这项工作中获得的知识应该有助于保护计划。

Infectious diseases are increasingly acknowledged as a leading health challenge for the 21st Century and as having major affects on biodiversity. The fascinating complexity of disease-host systems drives coevolution, as hosts are consistently pressured to evolve defenses and pathogens need to evolve new ways to evade them. This project will employ an experimental approach to test three questions fundamental to understanding coevolution of hosts and pathogens in a model system using tiger salamanders and an emerging virus. First, are pathogens locally adapted? Pathogens may perform better on local than foreign hosts, because pathogens generally evolve more quickly. Second, how should pathogens affect novel host species? Perhaps because they are locally adapted to native hosts, pathogens will not perform as well on naive species. Alternatively, new pathogens may perform well because naive hosts have not evolved defenses. Third, are hosts locally adapted? Host genetic variability, which will be directly manipulated, should play a key role in disease resistance. The broader impacts of the work are substantial because if pathogens are locally adapted, then potential treatments developed in one host population may not be effective in another. In addition, as global transport of pathogens can occur in days (e.g., SARS), and possibly for bioterrorism, research in model systems is crucial to understand effects of pathogens on novel hosts. Understanding effects of pathogens on novel host species can then lead to predictions regarding pathogen spread and disease emergence. Further, pathogens are implicated in the global decline of amphibians, and the knowledge gained from this work should help conservation programs.