Meeting Abstract
Understanding how biodiversity influences pathogen occurrence has global implications for predicting disease outbreaks and preventing additional biodiversity loss. The dilution effect hypothesis suggests that more diverse communities constrain pathogen spread through several mechanisms and recent meta-analyses suggest that the dilution effect is common. However, few studies of diversity-disease relationships have addressed the role of physiochemical properties that can influence community assembly and affect host and pathogen physiology. We used a system characterized by a multi-host pathogen, Ranavirus (RV), and complex assemblages of amphibians residing in ephemeral wetlands to quantify the relative contributions of biotic and abiotic factors on infection risk. We characterized the amphibian communities for 20 ephemeral wetlands and investigated the relationship between amphibian communities and ranavirus prevalence. We captured over 30,000 individual amphibians representing 23 species and quantified presence of ranavirus in a subset. Ranavirus prevalence varied significantly across species and wetlands. Based on boosted regression tree analyses, environmental variables including canopy cover and water and air temperature are the most important factors driving ranavirus occurrence. We saw no evidence of a dilution effect and no measure related to community ecology had a relative influence greater than 5%. Numerous factors related to abundances of species each had low relative influence and their combined influence suggests a role for community ecology in ranavirus dynamics. Still, the influence of environmental factors appears to be more important in determining patterns of ranavirus infection on the landscape.
