Infectious disease is a ubiquitous aspect of life on earth; however, parasites and pathogens are not distributed equally among individual hosts. Due to its ability to shape the way that individuals interact with other potential hosts and the environment, behavior is one of the most salient ways through which host biology varies in the context of disease. Variation in animal behavior can impact both transmission and the extent of a host's pathogen acquisition, and thus can have important consequences for infectious disease dynamics. Additionally, in this world of rapid urbanization where landscapes and wildlife resources are being altered, it is important to understand the ways in which human activity impact wildlife behavior, and in turn, disease dynamics. Here, we used both observational and experimental studies in field and laboratory settings to investigate the relationships among host behavior and physiology, anthropogenic food sources, and disease transmission in a natural host-pathogen system. First, we examined the relationship between house finch (Haemorhous mexicanus) stress physiology, exploratory behaviors, and social behaviors in the wild. We provided evidence that more exploratory house finches interact with more individuals in the wild, and have higher baseline concentrations of circulating stress hormones. Next, we found evidence that the amount of time spent on bird feeders drives both the acquisition and transmission of the bacterial pathogen Mycoplasma gallisepticum (Mg), indicating that variation in host foraging behavior has important transmission consequences in this system. Lastly, we found that the density of bird feeders available to house finches predicts the extent of Mg transmission in captivity. Taken together, these results highlight the important role that behavioral heterogeneity can play in the acquisition and spread of pathogens, as well as the potential impacts of human behavior on wildlife disease dynamics. Future work should seek to identify specific physiological mechanisms driving Mg acquisition and transmission as they relate to variation in host behavior, and the ways in which bird feeders impact disease-relevant behaviors in the wild. / Ph. D. / Infectious disease impacts almost every living creature on earth; however, some individuals are more likely to become sick and spread disease than others. Animal behavior can strongly influence disease dynamics due to its ability to shape the way that individuals interact with one another and the environment. Behavior can impact an individual’s likelihood of both acquiring and spreading disease, and thus can have important consequences for disease outbreaks. Additionally, as urban areas are expanding, it is important to understand the ways in which human activity impact wildlife behavior, and in turn, disease dynamics. Through both laboratory and field studies, we investigate the relationships among host behavior and physiology, human-related food sources, and disease transmission in a natural wildlife disease system. First, we examined the relationships between stress hormones, exploratory behaviors, and social behaviors of house finches, a common songbird. We provided evidence that more exploratory house finches interact with more individuals in the wild, and have higher concentrations of stress hormones. Next, we found evidence that the amount of time that house finches spend on bird feeders drives both the likelihood of acquiring and spreading conjunctivitis (=pink eye). This means that certain individuals are more likely to get sick and pass the disease on to others than other individuals are. Lastly, we found that when the density of bird feeders available to house finches is high, we see more disease transmission. Taken together, these 5 results highlight the important role that variation in behavior can play in acquiring and spreading disease, as well as the potential impacts of human behavior on wildlife health.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/78216 |
| Date | 16 June 2017 |
| Creators | Moyers, Sahnzi C. |
| Contributors | Biological Sciences, Hawley, Dana M., Belden, Lisa K., Walters, Jeffrey R., Hopkins, William A. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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