Thesis (M.SC.) - Carleton University, 2007. / Includes bibliographical references (p. 92-103). Also available in electronic format on the Internet.

Thesis (M. Sc.)--Carleton University, 1996. / Also available in electronic format on the Internet.

Thesis (Ph. D.)--Carleton University, 1997. / Also available in electronic format on the Internet.

Thesis (Ph. D.)--Illinois State University, 1999. / Title from title page screen, viewed July 24, 2006. Dissertation Committee: Steven A. Juliano (chair), Wayne A. Riddle, Scott K. Sakaluk, Charles F. Thompson, Douglas W. Whitman. Includes bibliographical references (leaves 126-133) and abstract. Also available in print.

Thesis (Ph. D.)--University of Washington, 1986. / Vita. Bibliography: leaves [174]-187.

No description available.

In 1960-63 populations of the song sparrow (Melospiza melodia (Wilson)) were studied on some of the islands along the Pacific Coast of southern British Columbia. The general problem was to find the factors that might be responsible for the regulation of numbers of any small passerine species. A more specific problem was to explain the extremely high population density of the song sparrows on Mandarte Island compared with densities elsewhere. Most individuals on Mandarte Island were colour marked, and changes in population density and behaviour were observed throughout the breeding season and at intervals during the rest of the year. Environmental conditions on Mandarte Island were compared with those on other islands in the area. All islands were alike in having similar weather and few predators; they differed in the kind of vegetation. The high density of the Mandarte Island population seems to have been a result of the simplicity of the habitat, which favours song sparrows and not their potential competitors, and of the adaptability of song sparrows in utilizing common feeding grounds in undefended areas outside their usual habitat. The critical period in the regulation of numbers was the autumnal territorialism, when increased territorial activities resulted in heavy losses and emigration of the young to areas with lower densities. / Science, Faculty of / Zoology, Department of / Graduate

Polygenic adaptation in response to selection on quantitative traits is thought to be ubiquitous in humans and other species, yet this mode of adaptation remains poorly understood. We investigate the dynamics of this process, assuming that a sudden change in environment shifts the optimal value of a highly polygenic quantitative trait. We find that when the shift is not too large relative to the genetic variance in the trait and this variance arises from segregating loci with small to moderate effect sizes (defined in terms of the selection acting on them before the shift), the mean phenotype's approach to the new optimum is well approximated by a rapid exponential process first described by Lande (1976). In contrast, when the shift is larger or large effect loci contribute substantially to genetic variance, the initially rapid approach is succeeded by a much slower one. In either case, the underlying changes to allele frequencies exhibit different behaviors short and long-term. Over the short term, strong directional selection on the trait introduces small differences between the frequencies of minor alleles whose effects are aligned with the shift in optimum versus those with effects in the opposite direction. The phenotypic effects of these differences are dominated by contributions from alleles with moderate and large effects, and cumulatively, these effects push the mean phenotype close to the new optimum. Over the longer term, weak directional selection on the trait can amplify the expected frequency differences between opposite alleles; however, since the mean phenotype is close to the new optimum, alleles are mainly affected by stabilizing selection on the trait. Consequently, the frequency differences between opposite alleles translate into small differences in their probabilities of fixation, and the short-term phenotypic contributions of large effect alleles are largely supplanted by contributions of fixed, moderate ones.

No description available.

No description available.