Meeting Abstract
P3.121 Monday, Jan. 6 15:30 Differences in susceptibility to the amphibian pathogen Batrachochytrium dendrobatidis across host age BRADLEY, P. W.*; BLAUSTEIN, A. R.; Oregon State University; Oregon State University paul.bradley@science.oregonstate.edu
Metamorphosis can be a stressful period for amphibians with the transition from an aquatic and herbivorous lifestyle to that of a more terrestrial and carnivorous lifestyle. The amphibian immune system is believed to be down-regulated during and through this period of transition leaving recently-post-metamorphic frogs in an immunosuppressed state. One ecologically important disease of amphibians is chytridiomycosis, which is caused by the fungal pathogen Batrachochytrium dendrobatidis. Negative effects of infection are believed to be stronger in the post-metamorphic life stage, and there is some evidence to suggest that recently-post-metamorphic frogs are at the most risk to the negative effects of the disease. Our experiment was designed to test the hypothesis that susceptibility to infection, and survival after infection, vary as recently-post-metamorphic frogs age. We raised two species of amphibians (Pseudacris regilla and Rana aurora) to metamorphosis and subsampled a portion of these individuals at various time points following metamorphosis: approximately 1, 2, and 3 weeks post-metamorphosis and 1, 3, 5, 7, and 9 months post-metamorphosis. At each time point, we exposed individuals to the pathogen and monitored survival and infection load. We exposed individuals to one of two concentrations of the pathogen: a fixed number of infectious particles across all ages, or a mass-specific concentration based upon the average mass of the individuals at that time point. Counter to our initial predictions, in both species survival was highest at the earliest time points and only at the later time points did we observe the expected levels of mortality. Additionally, this trend of increased pathogen-induced mortality with age was consistent across both pathogen-exposure concentrations.
