Term of Award

Winter 2023

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.


Department of Biology

Committee Chair

Aaron Schrey

Committee Member 1

Jennifer Brofft-Bailey

Committee Member 2

Robert Mans


Epigenetics is the study of molecular modification of a genome without changing its base pairs. The most studied type of epigenetic mechanism is DNA methylation, which is capable of turning a gene “on” or “off.” Epigenetic potential is the capacity to which an individual can have methylation on its genome. The more CpGs available, the greater the epigenetic potential. In invasive species, genetic variation has been observed to be paradoxical: not much of it exists on a genomic level, but epigenetically, phenotypic variation can occur. The focus on shift in gene expression in this study is on Toll-Like Receptor 4 (TLR4). TLR4 is a gene responsible for microbial surveillance measured here in a controlled environment where house sparrows are challenged with Salmonella enterica. Utilizing Qiagen DNeasy kits and targeted enzymatic methyl-sequencing on 38 hepatic tissue samples from house sparrows, it was found that sex and body mass do not impact DNA methylation of an individual sparrow, but the acute stressor (Salmonella) does impact methylation. This is the first study to prove not only that DNA methylation is impacted by stress and not other biological factors in sparrows, but that epigenetic potential provides the potential for response, DNA methylation states actualize the response, and the response is mediated through changes in gene expression.

Research Data and Supplementary Material