Extrinsic and intrinsic factors impacting Cape ground squirrels’ hair cortisol
| dc.contributor.author | Williams, Jenna | |
| dc.contributor.examiningcommittee | Anderson, Gary (Biological Sciences) | |
| dc.contributor.examiningcommittee | Koper, Nicola (Natural Resources Institute) | |
| dc.contributor.supervisor | Waterman, Jane | |
| dc.date.accessioned | 2025-01-15T15:29:31Z | |
| dc.date.available | 2025-01-15T15:29:31Z | |
| dc.date.issued | 2024-12-19 | |
| dc.date.submitted | 2024-12-19T21:45:35Z | en_US |
| dc.date.submitted | 2025-01-14T17:29:15Z | en_US |
| dc.date.submitted | 2025-01-14T21:57:31Z | en_US |
| dc.degree.discipline | Biological Sciences | |
| dc.degree.level | Master of Science (M.Sc.) | |
| dc.description.abstract | Glucocorticoids (GCs) increase during the stress response, so they are commonly studied to measure the chronic stressors an animal experiences. However, GCs can also decrease in response to stimuli they are adapted to, also known as harsh conditions, as a mechanism to conserve energy. Because GCs are closely linked to fitness and survival, understanding how animals' GC levels respond to their environment is crucial. Therefore, this thesis aims to study the changes in hair cortisol, a common GC studied in mammals, of an arid-adapted, egalitarian social species, Cape ground squirrels (Xerus inauris), due to extrinsic and intrinsic factors. We also explored the impact of GCs on reproductive success in adult females. We first examined cortisol responses to temperature, rainfall, and group size in adult female Cape ground squirrels across eight years. We found that squirrels illustrate a decrease in cortisol with increasing temperature maximums, suggesting that Cape ground squirrels are adapted to hot temperatures (harsh conditions) that require a metabolic response. There was no significant relationship between hair cortisol and temperature minimums, rainfall, or group size. We then examined hair cortisol and its relationship with intrinsic factors and reproductive success in adult female Cape ground squirrels. Age, body condition, ectoparasite abundance, and prevalence of nits did not have a significant relationship with cortisol. We also found that decreases in cortisol were associated with a lower reproductive success rate, also supporting that cortisol in these squirrels reflects metabolic energy needed for reproduction. Cape ground squirrels are income breeders, so they spend energy on reproduction when it becomes available. Overall, our research supports the hypothesis that hair cortisol in Cape ground squirrels reflects their metabolism and allocation of resources rather than chronic stress. This research is particularly relevant in the context of climate change, as understanding the relationships between GCs, reproduction, and environmental factors will become increasingly important as Cape ground squirrels' habitats continue to change. | |
| dc.description.note | February 2025 | |
| dc.identifier.uri | http://hdl.handle.net/1993/38813 | |
| dc.language.iso | eng | |
| dc.subject | Harshness | |
| dc.subject | Stress | |
| dc.subject | South Africa | |
| dc.subject | Metabolism | |
| dc.subject | Reproductive success | |
| dc.subject | Temperature | |
| dc.title | Extrinsic and intrinsic factors impacting Cape ground squirrels’ hair cortisol | |
| local.subject.manitoba | no | |
| oaire.awardNumber | 47338 | |
| oaire.awardTitle | R.G. and E.M. Knight Graduate Fellowship | |
| project.funder.identifier | http://dx.doi.org/10.13039/100010318 | |
| project.funder.name | University of Manitoba |