The Impact of Late Quaternary Climate Change on Mammals Along an Elevational Gradient

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This study investigates the response of Neotoma (woodrats) to climatic change over the last 15,000 years along a severe elevational and environmental gradient. During the Pleistocene, lake Manly covered much of Death Valley; its abrupt draining in the mid-Holocene led to dramatic shifts in temperature and aridity. Today this area is the hottest and driest in the Western Hemisphere. By combining fieldwork, examination of museum specimens, and collection of paleofossils, this project will reconstruct the divergent evolutionary histories of animals from the Valley floor and along a nearby mountain gradient (-84 to 3400m). The investigators predict fundamental differences in the adaptive abilities of woodrat species related to elevation of the site and local microclimate. Predicted responses include: i) local extirpation when temperature thresholds are exceeded, ii) generation of novel adaptations, such as new life histories, and iii) morphological alterations, such as phenotypic changes in body size. The broader impacts of the work include the ability to characterize the relationship between the magnitude and rapidity of temperature shifts, the position in the geographic range, and the type of elucidated response. Such information about the responses of organisms to past climate change is invaluable for scientists studying anthropogenic warming. Moreover, the project will generate a high quality spatial and temporally resolved climate proxy that can be integrated with other paleodata. The characterization and interpretation of late Quaternary climates is a major research effort of governmental and geoscience agencies.