Dissertation Defense Announcement
College of Arts and Sciences announces the Final Dissertation Defense of
for the Degree of Doctor of Philosophy
March 28, 2019 at 1:00 PM in Ellington Hall,Room 105
Advisor: Matthew Parris
Investigating the impacts of the fungal pathogen, Batrachochytrium dendrobatidis, on growth, behavior, and reproductive investment in salamanders.
ABSTRACT: The fungal pathogen Batrachochytrium dendrobatidis (Bd) has been implicated in amphibian declines. Bd infects the skin of post-metamorphic individuals, leading to disruption of epidermal function and death from cardiac arrest. However, susceptibility to Bd varies among species. Many species carry sublethal infections, which can alter growth, behavior, and reproduction. The goals of these experiments were to determine the impact of Bd on growth and body condition, feeding behavior, performance, and reproductive investment in salamanders. Post-metamorphic spotted salamanders (Ambystoma maculatum) were monitored for 12 weeks to examine growth, and the amount of food that they consumed was recorded. Bd infection lead to reduced growth in post-metamorphic spotted salamanders but did not alter the amount of food consumed. Though all exposed salamanders became infected, Bd loads decreased over time, with most individuals clearing infection. Susceptibility of adult spotted salamanders was assessed, and the impacts of Bd on feeding behavior and skin sloughing were determined. In adult spotted salamanders, exposure to Bd results in low infection prevalence and load. Adult salamanders did not exhibit differences in the amount of food consumed, nor did they differ in feeding behavior. Body condition was not impacted by exposure to Bd, nor was the amount of skin slough produced. We also determined the impacts of Bd on burst speed, activity levels, and feeding behavior in red-spotted newts, a species with high Bd prevalence in the wild. 75% of exposed newts had detectable infections 4 weeks post-exposure. Infected newts did not differ from controls in burst speed, activity levels, or feeding behavior. Additionally, there was no difference in percent change in body mass after 95 days. To assess the impact of Bd on reproductive effort, the gonad mass of female red-spotted newts was examined. Newts infected with Bd did not differ in reproductive investment, as the size corrected ovary, oviduct, and fat body mass did not differ between groups. However, though some species of salamanders experience decreasing infection loads and eventually lose infection, the infection loads of red-spotted newts increased from 4 to 8 weeks post-exposure. Overall, these results highlight the varied response of amphibians to Bd.