Honors Theses
Date of Award
Spring 5-10-2025
Document Type
Undergraduate Thesis
Department
Biology
First Advisor
Michel Ohmer
Second Advisor
Isis da Costa Arantes
Third Advisor
John Samonds
Relational Format
Dissertation/Thesis
Abstract
Climate change and the disease chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), are the two main drivers of amphibian decline worldwide, but it is difficult to predict the outcomes of these interacting stressors. Amphibians are ectotherms meaning they are dependent on environmental temperature for the maintenance of physiological processes, and they rely on behavioral thermoregulation to maintain body temperatures within their thermal limits. As the climate becomes more variable, amphibians are also potentially more susceptible to diseases such as Bd, as their immune defenses, such as antimicrobial peptide (AMP) defenses of the skin, take longer to acclimate to temperature shifts. This study sets out to investigate the impact of AMP-depletion and Bd infection on the thermal preference of a widespread North American amphibian, the green frog, Rana clamitans. Thermal preference was measured before and after treatment, which consisted of injection with norepinephrine (low or high dose) to deplete AMP stores from the granular glands, a control injection (APBS), or only handling. Treatment had no effect on thermal preference, but norepinephrine injection did result in increased Bd infection in those groups. In addition, infected frogs selected lower temperatures overall, and this was load dependent, with selected temperature decreasing as load increased. This was opposite to predictions, as warmer temperatures can help amphibians clear Bd infections. However, infected amphibians' continual movement throughout the thermal gradient can result in reduced body temperatures overall. This study was a first step in understanding the links between AMPs, Bd infection, and thermal physiology in amphibians, in order to better understand the complex interactions between climate change and disease in this imperiled taxon.
Recommended Citation
Salvador, Kim M., "The Impact of Antimicrobial Peptide Depletion and Fungal Infection On Thermal Preference In Green Frogs, Rana Clamitans" (2025). Honors Theses. 3351.
https://egrove.olemiss.edu/hon_thesis/3351
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