Frog and salamander species are declining worldwide, some apparently due to the emergence of new or more severe diseases. While the precise causes of these epidemics are unclear, they are likely to be influenced by human-induced environmental changes affecting both exposure and susceptibility of amphibians to pathogens. Temperature-dependent immunity may be particularly important to disease dynamics in amphibians, leading to increased susceptibility to infection in springtime or under changing climatic conditions. This project uses the Red-spotted newt, a common temperate salamander, as a model species for studying: (1) seasonality in infection and immunity in amphibians, (2) factors leading to outbreaks of an Ichthyophonus-like fungus implicated in recent amphibian die-offs, and (3) ecological processes structuring the newt parasite community. Capture-mark-recapture methods coupled with lab and field experiments will be used to test hypotheses which explain patterns observed in spatial and seasonal surveys of newt populations and their parasites. This research will provide insights into the effects of seasonal temperature fluctuations on amphibian immune defenses, the transmission dynamics of an important fungal pathogen, and the community ecology of amphibian parasites. Studying multiple immune parameters and parasite species in newts will lead to a broader impact on our understanding of how human-induced environmental changes affect disease dynamics in amphibian populations, by providing insight into general principles of amphibian disease ecology. This project will support the dissertation research of a doctoral candidate.
