Electronic Theses and Dissertations

Date

2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Biology

Committee Chair

Matthew Parris

Committee Member

Kimberly Terrell

Committee Member

Michael Ferkin

Committee Member

Omar Skalli

Abstract

Amphibians are declining globally, with the fungal pathogen Batrachochytrium dendrobatidis (Bd) implicated as a contributing factor. Bd infects keratinized tissue of amphibians, including the skin of post-metamorphic individuals. Susceptibility to Bd varies among species, with many carrying sublethal infections, which can alter growth, behavior, and reproduction. The goals of these experiments were to determine the impact that Bd has on growth and body condition, feeding behavior, performance, and reproductive investment in salamanders with sublethal infections. The impacts of Bd infection on growth were assessed in post-metamorphic spotted salamanders (Ambystoma maculatum). They were monitored for 12 weeks, and the amount of food that they consumed was recorded. Our results show that Bd infection leads to reduced growth in post-metamorphic spotted salamanders, though it did not alter the amount of food consumed. Bd loads in spotted salamanders 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. Exposure of adults to Bd resulted in low infection incidence. Bd-exposed adult salamanders did not exhibit differences in the amount of food consumed, feeding behavior, or body condition. Further, skin sloughing in Bd exposed individuals did not differ from uninfected controls. We examined the impacts of Bd infection on burst speed, activity levels, and feeding behavior in the red-spotted newt (Notophthalmus viridescens). Bd infection did not impact these variables. Additionally, there was no difference in percent change in body mass between infected and control newts after 95 days. To assess the impact of Bd on reproductive effort, the gonad mass of female red-spotted newts was examined. Bd infection did not impact reproductive investment, as the size-corrected ovary, oviduct, and fat body mass did not differ between groups. However, though some species of salamanders have decreasing infection loads and eventually lose infection, the infection loads of the red-spotted newts fluctuated. Further, infected female newts gained less mass than unexposed newts, though this effect took 16 weeks to become apparent. Overall, these results highlight the varied response of amphibians to Bd and demonstrate the importance of long-term studies.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to ProQuest

Notes

embargoed

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