This thesis investigates the molecular evolution of the cytosolic glyceraldehyde 3-phosphate dehydrogenase (GapC) gene family in two varieties of Amsinckia spectabilis (Boraginaceae) that differ in mating system. Examination of sequence variation suggests that the gene family consists of three or four members. Compared with GapC in Arabidopsis thaliana, the GapC locus in A. spectabilis has at least two fewer introns and one intron that is double in length. Strong purifying selection was detected at each putative locus since the divergence of the Amsinckia spectabilis lineage from species in the allied family Solanaceae. Mean nucleotide diversity across all observed loci is 0.0036 for the inbreeding variety spectabilis, and 0.0049 for the outbreeding variety microcarpa . Outbreeding populations were systematically more diverse than inbreeding populations at GapC-IV. These results are discussed in the context of theory for the fate of duplicate genes, and the background selection hypothesis.

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Thesis (M.S.) in Resource Economics and Policy--University of Maine, 2004. / Includes vita. Includes bibliographical references (leaves 133-134).

Thesis (M.S.) in Forestry--University of Maine, 2006. / Includes vita. Includes bibliographical references (leaves 53-58).

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A greenhouse study was undertaken to investigate some relationships between nutrition of the host tree, Abies amabilis, as influenced by soil fertility and nitrogen fertilizers, and biology of the balsam woolly aphid, Adelges piceae (Ratz.). Seedlings were reared in two soil regimes - nutrient-deficient mineral soil and enriched humic soil. All trees were infested with aphid larvae, and observations made to determine the influence of soil fertility on the establishment rate of larvae on host trees. Subsequently, groups of 10 trees were treated with foliar nutrients, using ammonium nitrate and urea in various concentrations. The establishment rate of larvae on humic soil host trees was 2.5 times greater than on mineral soil trees. In addition, growth rate of the aphid population on humic soil trees was 37% greater than on mineral soil trees over a four week period. Soil fertility also influenced the life history of the insect. One foliar nutrient adversely affected the aphid population. Over a 10 week period, the aphid population on trees treated with 1% ammonium nitrate decreased by 23%, whereas the control population Increased 30.9%. It is postulated that this foliar treatment manifests its adverse effect primarily by inhibiting initial settling of larvae on the host trees. This inhibition may be related to fertilizer-induced alterations in the amino acid composition of feeding tissue. / Science, Faculty of / Zoology, Department of / Graduate

Thesis (M.S.)--Oregon State University, 2005. / Printout. Includes bibliographical references (leaves 45-49). Also available on the World Wide Web.

Thesis (M.S.) in Forestry--University of Maine, 2008. / Includes vita. Includes bibliographical references (leaves 59-67).

Thesis (M.S.)--West Virginia University, 2010. / Title from document title page. Document formatted into pages; contains x, 78 p. : ill. (some col.), col. maps. Includes abstract. Includes bibliographical references.