Date of Award

Summer 8-15-2016

Author's School

Graduate School of Arts and Sciences

Author's Department

Biology & Biomedical Sciences (Evolution, Ecology & Population Biology)

Degree Name

Doctor of Philosophy (PhD)

Degree Type



Climate is widely recognized as a primary factor contributing to species distribution limits. In turn, species’ geographic ranges have contracted and expanded in concert with Earth’s climatic history and are predicted to shift in response to future climate change. We investigated the ecological and genetic consequences of species distributions in flux with their historical, current, and projected future climatic environments. Chapter 1 introduces themes and background information related to the thesis research found in Chapters 2 through 4. In Chapter 2, we questioned the extent to which ancestral climate-related traits are conserved through vast periods of evolutionary time spanning the Cenozoic. We found a significant correlation between mean annual temperatures experienced by ancestral plant species and those of their modern descendants, supporting the theory that plant lineages have largely tracked suitable climates throughout Earth’s history. In Chapter 3, we used niche modeling applications to predict the locations where whitebark pine (Pinus albicaulis Engelm.), a threatened high elevation tree species, may seek refuge with future climate change. We found regions dominated by Wilderness Areas where whitebark pine is predicted to perform well, and our results supported the species future climatic niche shift with respect to elevation but not latitude. We suggested offsetting the species’ expected reduction in high elevation habitat by returning to a more prevalent fire regime, which was historically important to the species survival among competitive shade tolerant taxa at lower elevations. In Chapter 4, we examined the genetic consequences of the Last Glacial Maximum on phylogeographic patterns of whitebark pine. Significant patterns of isolation by distance were detected by latitude and longitude, and species population structure was poorly defined. Whitebark pine genetic partitioning was low within and among populations, which may benefit the species as it becomes increasingly endangered by pests, pathogens, climate change, and reduced fire frequency. As the threat of anthropogenic climate change is on the rise, future studies will benefit conservation efforts by further untangling the array of ecological and genetic impacts associated with a changing climate. Chapter 5 presents the thesis conclusion, tying together research findings from Chapters 2 through 4.


English (en)

Chair and Committee

Barbara A. Schaal

Committee Members

Kenneth M. Olsen, Peter H. Raven, Justin C. Fay, Jonathan A. Myers, Scott A. Mangan


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