| Summary: | 79 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006. Plant response to climate change can occur through a variety of mechanisms including population migration and phenotypic evolution. The effects of migration are often preserved in genetic patterns of contemporary forests, and can include genetic drift during population fragmentation as well as genetic bottlenecks during founder events. Besides migration, populations often change phenotypically in response to shifting climates. In this study I quantify genetic and morphological patterns of central and western North American white spruce populations. Specifically I have (1) provided evidence supporting Hulten's long standing hypothesis that ice-free areas of Beringia served as northern refugia for arctic and boreal biota during the last Quaternary glaciation using cpDNA markers, (2) provided evidence for multiple refugia in Alaska and uncovered the roles of gene flow and drift in structuring the patterns we see today and (3) teased apart the controlling mechanisms behind morphological expression (genetics, environment, or genetic x environmental interactions) in traits by comparing needle morphologies of common garden and naturally grown individuals.
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