碩士 / 國立臺灣師範大學 / 生命科學研究所 / 102 / Ambient temperature is one of the key mechanisms determining species range limits. Small mammals in Taiwan are known for their distinct elevational distribution. For example, of the two Apodemus species, A. agrarius distributes at lower elevation and A. semotus distributes at higher elevation. Given the close relationship between temperature and elevation, species’ elevational distribution may reflect their thermal niche. Previous studies showed that the two Apodemus species are different in their thermal physiology in that A. agrarius has lower tolerance for low temperature whereas A. semotus has more difficulties to dissipate their body heat in high temperature. In this study, I used the pair of A. agrarius and A. semotus as a model system to investigate if thermal niche influences elevational distribution of closely related small mammal species. I used laboratory experiments to establish their thermal niche by subjecting them to low (15oC-21oC), intermediate (21oC-27oC) or high (27oC-33oC) temperature environment, and monitoring their body condition. I predicted their geographic distribution based on the fundamental thermal niche established in the laboratory. In addition, I used ecological niche modeling to predict habitat suitability of these two species, which was then used to extract temperature data that represent their realized thermal niche. The laboratory experiment showed that A. agrarius lost weight under low temperature treatment whereas A. semotus were not influenced by temperature treatments. For A. agrarius, the laboratory experiment and ecological niche model showed consistent patterns in predicted distribution and thermal niche, suggesting this species’ geographic distribution is likely limited by its own thermal niche. In contrast, according to the fundamental thermal niche from the current laboratory experiment as well as a previous experiment, A. semotus should be widely distributed across the entire Taiwan, which was inconsistent with the predicted distribution from the ecological niche model. For A. agrarius, the thermal niches established by extracting temperature data of the predicted distribution were similar whether the prediction distribution was based on the laboratory experiment or ecological niche model. In contrast, the thermal niches based on the laboratory experiment and ecological niche model were dissimilar for A. semotus. Therefore, this study suggests that the geographic distribution of A. agrarius is primarily restricted by its fundamental thermal niche, but that of A. semotus may be further restricted by factors other than temperature.
| Identifer | oai:union.ndltd.org:TW/102NTNU5112035 |
| Date | January 2014 |
| Creators | 李苡柔 |
| Contributors | 李佩珍 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 60 |
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