Graduation Year

2019

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Biology (Integrative Biology)

Major Professor

Jason Rohr, Ph.D.

Committee Member

Loren Cassin Sackett, Ph.D.

Committee Member

Andrew Kramer, Ph.D.

Keywords

Anuran, Anorexia, Performance Metrics, Ecological Immunology, Helminth, Sickness Behavior

Abstract

Parasitic infections are ubiquitous in nature, and host-parasite dynamics can have powerful effects on wildlife populations. Many species have evolved behavioral responses to infection that can help mitigate damage from parasites. Anorexia is a common response to infection observed throughout the animal kingdom. Reducing nutrient intake can help shift host resources from digestion to immunity, as well as limit resources available to parasites. Reduced feeding can weaken the host, but in some host-parasite interactions, this cost is less than that of maintaining an infection. Here, I describe an experiment aimed to explore the effects of the parasitic nematode Aplectana hamatospicula on the Cuban treefrog (Osteopilus septentrionalis) across life stages. Tadpoles were exposed to A. hamatospicula larvae or a sham exposure and growth and behavior were quantified. After metamorphosis, the jumping performance of these frogs was assessed. I revealed that A. hamatospicula could infect and complete its lifecycle in tadpoles. This infection was unique in that it persisted through metamorphosis with the worm continuing to reproduce in the intestinal tract of the terrestrial frogs. These infections reduced the relative mass gain of tadpoles. However, post-metamorphic frogs were able to compensate for this lower growth when provided an ad libitum diet, and infection did not directly or indirectly impact jumping performance, perhaps because of this compensation. Tadpoles that prevented or cleared the infection had a higher rate of anorexia, suggesting that anorexia might be a successful disease-mitigation response to A. hamatospicula.

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