Meeting Abstract

P3.2  Sunday, Jan. 6  The Effects of Size Hierarchies on Infection and Transmission of Ranavirus in Amphibians EGDORF, T.C.*; KIRSCHMAN, L; CRESPI, E; BRUNNER, J; WARNE, R; Southern Illinois University Carbondale tcegdorf7@yahoo.com

The mechanisms that contribute to high variation in pathogenic infection dynamics among individuals in structured populations are poorly understood. Individual variation in exposure, susceptibility and recovery to infection are fundamental drivers of pathogen and disease dynamics in host populations. Yet, the physiological and behavioral determinants that underlie such individual variation in structured animal population have not been well examined. Here we use ranavirus, an emerging and directly transmitted disease of ectothermic vertebrates, to test the effects of size dependent physiology and behavior on disease susceptibility and transmission in wood frog larvae. Wood frog tadpoles naturally form large size hierarchies in which growth, development, stress physiology and immune function vary consistently with size. Presumably, these size dependent traits are also likely reflected in differences in behaviors as well. In this study, we hypothesized that larger individuals within a hierarchy would display more aggressive behaviors with higher contact rates that would increase the transmission rates of ranavirus within a population than their smaller counterparts. Counter to this process, however, we also hypothesized that smaller tadpoles would be more susceptible infection because of consistently higher concentrations of glucocorticoid hormones; an immunosuppressive hormone under chronic elevated levels. Through these efforts this study can provide insight into how population structuring and individual traits contribute to epidemic outbreaks of disease.