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dc.contributor.advisor Manos, Paul S en_US
dc.contributor.author Burge, Dylan O. en_US
dc.date.accessioned 2011-06-09T12:59:56Z
dc.date.available 2011-12-05T05:30:04Z
dc.date.issued 2011 en_US
dc.identifier.uri http://hdl.handle.net/10161/3924
dc.description Dissertation en_US
dc.description.abstract <p>Edaphic factors--those pertaining to the substrate or soil--are thought to play an important role in the diversification of flowering plants. Although edaphic factors are widely interpreted as causal agents in plant diversification, little is known about the evolutionary origin of most edaphic endemic plants, preventing inference of potential mechanisms by which substrate properties may influence speciation. The North American plant genus Ceanothus (Rhamnaceae) contains 9 edaphic-endemic species, taxa restricted to soils derived from specific geological materials. The three components of my dissertation research aim to improve understanding of how edaphic ecology has influenced the diversification of Ceanothus. First, I use DNA sequence data from the low-copy nuclear gene nitrate reductase to reconstruct the phylogeny of Ceanothus and elucidate diversification of this group into the California Floristic Province (CFP) of western North America, including the evolution of edaphic endemism. This research indicates that diversification of the two Ceanothus subgenera (Cerastes and Ceanothus) is centered on the CFP and is characterized by shallow divergence and phylogenetic relationships defined predominantly by geography. Divergence time estimation suggests that diversification of both Ceanothus subgenera began approximately 6 Ma. The nine edaphic-endemic taxa are not phylogenetically clustered in my analyses, suggesting that the origin of edaphic endemism has occurred on multiple occasions, including multiple examples of serpentine endemism. The second chapter of my dissertation uses soil chemistry data in combination with a more detailed examination of genetic variation in nitrate reductase to elucidate the evolution of a single edaphic endemic species.</p> en_US
dc.subject Biology en_US
dc.subject Systematic biology en_US
dc.subject Ecology en_US
dc.subject Ceanothus en_US
dc.subject edaphic en_US
dc.subject gabbro en_US
dc.subject phylogeny en_US
dc.subject Rhamnaceae en_US
dc.subject soil en_US
dc.title Evolution of Edaphic Ecology in Ceanothus (Rhamnaceae) en_US
dc.type Dissertation en_US
dc.department Biology en_US
duke.embargo.months 6 en_US

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