<p>Many endotherms use torpor on a seasonal or daily basis to conserve metabolic resources during difficult conditions, but the capacity to do so has never been recognized as varying intraspecifically. I hypothesized that populations that are exposed to prolonged cold, snow, or scarcity of food resources relative to other conspecifics may express torpor despite the fact that other conspecifics may not use, or even be capable of, torpor. I studied thermoregulation of black-tailed prairie dogs (<I>Cynomys ludovicianus</I>) and Ords kangaroo rats (<I>Dipodomys ordii</I>) at the extreme northernmost periphery of each species range to determine whether there is evidence for geographic variation in torpor patterns.</p><p>Contrary to previous studies of black-tailed prairie dogs near the centre of the species range, I found that northern prairie dogs hibernate during winter, spending up to 95 days per year in torpor. Synchrony of body temperature patterns of some individuals suggests that northern prairie dogs hibernate communally. Similarly, in contrast to previous studies of kangaroo rats in more southern localities, I found that northern Ords kangaroo rats use daily torpor during winter, entering torpor on up to 70 days per year. Kangaroo rats that use deep torpor exhibit comparable survival and pre-winter body mass, but poorer spring body condition, than kangaroo rats that do not use deep torpor. I reported the details of my procedures for studying thermoregulation of small mammals in the wild, to encourage comparable studies that would provide additional insights on intraspecific variation in torpor patterns. My findings are the first to demonstrate that the capacity for torpor varies predictably on a geographic basis.</p>
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:SSU.etd-04142005-071703 |
| Date | 14 April 2005 |
| Creators | Gummer, David Lee |
| Contributors | Michener, Gail R., Messier, François, Flood, Peter F., Clark, Robert G., Chivers, Douglas P., Bortolotti, Gary R. |
| Publisher | University of Saskatchewan |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-04142005-071703/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Saskatchewan or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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