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.
