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Development and utilization of molecular tools to understand invasion biology in Centaurea maculosa (spotted knapweed)


My doctoral research at Colorado State University was designed to create and utilize molecular tools to help understand ecological phenomena in the invasive weed, spotted knapweed (Centaurea maculosa Lam.). In this dissertation, I first introduce the need for research at multiple scales and the potential benefits of collectively examining molecular, physiological and ecological phenomena in an invasive plant. I then give a brief overview of the life history characteristics of spotted knapweed and report on the development and characterization of a spotted knapweed gene library. By utilizing sequence information from the gene library, I determined that both ploidy (diploid or tetraploid) and origin (native or invasive) influence expression of genes that may be important for plant defense in spotted knapweed populations. I found that spotted knapweed can differentially respond to strong or weak competitors at the level of gene expression by using existing molecular tools from a model plant coupled with sequence information from the gene library. In addition, I found that plant neighbor identity, simulated herbivory and resource availability are all important factors that influence accumulation of biomass and secondary metabolites in both spotted knapweed and a native grass species. I utilized molecular tools to demonstrate that spotted knapweed infestation alters the composition of North American soil fungal communities; however, the ecological ramifications of this observation remain undetermined. The major goal of my research was to better understand spotted knapweed invasion biology by utilizing molecular tools. I believe this approach was successful in that it led to a variety of interesting results. However, more research is required to fully link these molecular findings with ecological and physiological aspects of spotted knapweed invasion biology. It is my hope that the chapters of this dissertation highlight both the opportunities and limitations associated with using molecular tools to understand invasion biology in this system.


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Centaurea maculosa
EST library
gene expression
invasive weeds
soil microbiology
spotted knapweed
molecular biology


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