Functional roles of Arctic foxes in tundra ecosystems: ecosystem engineering, nutrient transport, and consumptive and non-consumptive effects on prey
| dc.contributor.author | Johnson-Bice, Sean | |
| dc.contributor.examiningcommittee | Gillis, Darren (Biological Sciences) | |
| dc.contributor.examiningcommittee | Costamagna, Alejandro (Entomology) | |
| dc.contributor.examiningcommittee | Nol, Erica (Trent University) | |
| dc.contributor.supervisor | Roth, James | |
| dc.date.accessioned | 2024-08-26T20:36:29Z | |
| dc.date.available | 2024-08-26T20:36:29Z | |
| dc.date.issued | 2024-08-15 | |
| dc.date.submitted | 2024-08-15T21:55:31Z | en_US |
| dc.degree.discipline | Biological Sciences | |
| dc.degree.level | Doctor of Philosophy (Ph.D.) | |
| dc.description.abstract | Predators are widely recognized for their irreplaceable roles in influencing the abundance and traits of lower trophic levels. Yet, predators also shape community interactions and ecological processes via localized pathways, irrespective of their influence on prey density or behavior. I synthesized empirical and theoretical research and identified pathways by which predators have indirect ecological effects confined to discrete patches. This synthesis revealed how predators indirectly affect other species via patches – ranging from mediating scavenger interactions to influencing parasite/disease transmission risk – and ultimately provides a more holistic view of predation in ecosystems. I then demonstrated how satellite imagery could resolve whether Arctic foxes create biogeochemical hotspots via their denning behavior. Using satellite imagery, I showed that Arctic fox dens have greater plant productivity and green-up faster than reference sites, supporting the hypothesis that Arctic foxes cause the unique vegetation on their dens by concentrating nutrients derived from prey remains there. I then assessed how predators influence the reproductive ecology of Canada geese. Birds presumably select nest sites in areas they perceive are safer, but few links between spatial patterns of risk and nest habitat selection or nesting success exist. By comparing habitat selection models fit to goose nest locations and fox movement locations, I showed predator activity strongly affects the spatial distribution and reproductive success of geese. However, these effects were mediated by the date nest incubation started, revealing how nesting phenology and predator activity interact to shape bird reproduction. Finally, I assessed how fox predation affects goose reproductive success from an ecosystem-level perspective. I showed winter environmental conditions influence the abundance and availability of main winter foods for Arctic foxes, which in turn showed a numerical response to these foods and ultimately had a negative effect on goose reproductive success. These results demonstrate apparent competition between rodents and geese, and establish a link between the marine and terrestrial environments via Arctic fox use of marine subsidies. Given the importance of climate in mediating these trophic relationships, I contextualize the results of this thesis within ongoing climate change and highlight the vulnerability of coastal tundra ecosystems in a warming Arctic. | |
| dc.description.note | October 2024 | |
| dc.description.sponsorship | I and the research underlying this dissertation were supported financially by the Natural Sciences and Engineering Research Council of Canada, Natural Resources Canada Polar Continental Shelf Program, Environment and Climate Change Canada, the University of Manitoba, the CNSC, the American Museum of Natural History, National Geographic, the American Society of Mammalogists, and the Explorers Club. | |
| dc.identifier.uri | http://hdl.handle.net/1993/38428 | |
| dc.language.iso | eng | |
| dc.rights | open access | en_US |
| dc.subject | Arctic fox | |
| dc.subject | Ecology | |
| dc.subject | Climate change | |
| dc.subject | Arctic tundra | |
| dc.subject | Predator-prey ecology | |
| dc.subject | Ecosystem engineering | |
| dc.title | Functional roles of Arctic foxes in tundra ecosystems: ecosystem engineering, nutrient transport, and consumptive and non-consumptive effects on prey | |
| dc.type | doctoral thesis | en_US |
| local.subject.manitoba | yes | |
| project.funder.identifier | https://doi.org/10.13039/501100000038 | |
| project.funder.name | Natural Sciences and Engineering Research Council of Canada |