Northrup, Joseph M.

DNA methylation (DNAm) is a useful indicator of phenotypic expression and diversity, and can potentially inform adaptations to environmental changes. This thesis uses epigenetic techniques to investigate the mechanisms underlying phenotypic variation in white-tailed deer, black bear, and mountain goat, with a particular focus on age and body size. In the second chapter, we aimed to contribute to wildlife monitoring by developing epigenetic clocks, or predictive models of age, and diagnostic markers of age class and sex. In the third chapter, we aimed to investigate the involvement of DNAm in body size variation of white-tailed deer by developing a model predictive of hindfoot length, and by identifying CpGs and genes that may be involved in hindfoot length variation. My results indicate that DNAm is an effective predictive marker of various phenotypes in these North American large mammals, and that epigenetic methods offer valuable insights for managing human impacts on wildlife.

Author Keywords: Age, Body Size, DNA Methylation, Epigenetics, Phenotypes, Population Genetics

Assessments of the adaptive potential of natural populations are essential for understanding and predicting responses to environmental stressors like climate change and infectious disease. The range of stressors species face in a human-dominated landscape, often have contrasting effects. White-tailed deer (Odocoileus virginianus, deer) are expanding in the northern part of their range following decreasing winter severity and increasing forage availability, caused by climate change. Chronic wasting disease (CWD), a prion disease affecting cervids, is likewise expanding and represents a major threat to deer and other cervids We obtained tissue samples from free-ranging deer across their native range in Ontario, Canada which has yet to detect CWD in wild populations of cervids. High throughput sequencing was used to assess neutral genomic variation and variation in the gene responsible for the protein that misfolds into prions when deer contract CWD, known as the PRNP gene. Neutral variation revealed a high number of rare alleles and no population structure, consistent with an expanding population of deer. Functional genetic variation revealed that the frequencies of variants associated to CWD susceptibility and disease progression were evenly distributed across the landscape and the frequencies were consistent with deer populations not infected with CWD. These findings suggest that an observable shift in PRNP allele frequencies likely coincides with the start of a novel CWD epidemic. Sustained surveillance of genomic and genetic variation can be a useful tool for CWD-free regions where deer are managed for ecological and economic benefits.

Author Keywords: Canadian wildlife, population genetics, prion, PRNP, RADseq, ungulate