Understanding how biodiversity influences pathogens has global implications for predicting disease outbreaks and preventing additional biodiversity loss. The dilution effect hypothesis suggests that more diverse communities constrain pathogen infection due to an increased abundance of incompetent hosts. I investigated the relationships between spatial and temporal changes in amphibian biodiversity and prevalence of ranavirus, an important pathogen implicated in amphibian declines. I gathered amphibian community data for 20 ephemeral wetlands using standardized trapping methods. For a subset of individuals (2,210), I quantified presence and load of ranavirus using quantitative PCR. Results indicate wetland canopy cover and air and water temperature values are the most informative predictors of ranavirus occurrence. Daily ambient air temperature, anuran size, emergent vegetation and canopy, and prevalence were the best predictors of viral load. These results suggest rising temperatures could be very problematic for amphibians and the importance of community interactions may be masked by environmental factors.
