Local and broad scale changes in North American small mammal community structure: the late Pleistocene through the late Holocene
Open Access
- Author:
- Pardi, Melissa Irene
- Graduate Program:
- Geosciences
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- November 11, 2009
- Committee Members:
- Russell W Graham, Thesis Advisor/Co-Advisor
Russell W Graham, Thesis Advisor/Co-Advisor - Keywords:
- multivariate analysis
paleoecology
Holocene
Pleistocene
glacial
small mammals
non-analog - Abstract:
- A new late Quaternary fauna from Don’s Gooseberry Pit in the Black Hills of South Dakota provides the first continuous late Pleistocene through late Holocene paleobiological record for the North American Northern Great Plains. A paleoecological history of the Black Hills was constructed using the small mammal remains from this cave. In addition, twelve radiocarbon dates were taken from dental elements of specific taxa to identify non-analog associations. A cluster analysis of samples indicate that Don’s Gooseberry Pit contains a fauna that is representative of a cold moist environment in the late Pleistocene, which then transitions into a drier and more open late Holocene environment. This over-all trend was accomplished through episodic changes from closed to open forest, and not a linear change from cold to warm. This finding is consistent with other climate records. Despite careful excavation procedures, mixing in the Don’s Gooseberry Pit is extensive, as evidenced by the twelve radiocarbon dates. More radiocarbon dates on individual taxa may reveal a non-analog fauna in the future. Plotting dated specimens in a chronology, however, revealed that organisms followed an individualistic response to climate change. This pattern is also consistent with the cluster analysis. To examine large scale patterns in small mammal community structure, 203 fossil faunas from 183 locations east of the Rocky Mountains in North America were compared using non-metric multidimensional scaling. These faunas ranged in age from the last Full Glacial to the late Holocene. Late Glacial faunas were more diverse than late Holocene faunas. Glacial sites were also more taxonomically similar along an East-West gradient. This finding suggests that this gradient steepened during the transition into the Holocene. Heterogeneous environments during the last glacial could produce such patterns, and are also consistent with the presence of late Pleistocene non-analog faunas. These results indicate that North America not only experienced extinctions of organisms at the end of the last glacial, but that some late Pleistocene habitats were also wiped from the modern landscape. These findings provide relevant details about how future climate change may affect patterns in terrestrial biodiversity.