Geographically peripheral populations are believed to be particularly important in a species' response to environmental change and for the conservation of intraspecific genetic diversity. It is expected that as a species' range limits are approached, productivity and reproduction will decline and populations will become less abundant and more isolated. Decreased genetic variability and increased genetic divergence of peripheral populations is predicted based on these patterns. Cirsium heterophyllum reaches a southern geographical limit in the UK, C. acaule and C. eriophorum reach a northern limit and C. arvense occurs throughout the UK. These species have been used to determine whether contemporary patterns of distribution, productivity and reproductive potential across a species' UK latitudinal range are reflected in the predicted patterns of population genetic structure (assessed using microsatellite markers). Population frequency declines approaching the periphery of Cirsium acaule and C. heterophyllum. A decline in abundance was found in C. heterophyllum only. Community surveys suggest that peripheral populations do not occur in atypical habitat. There is no latitudinal variation in morphological characters across the species range, whereas reproductive potential declines approaching the periphery of the species that reach a latitudinal limit in the UK. Population genetic analysis revealed a decline in genetic variation toward the latitudinal limit of C. acaule. This pattern is absent in C. heterophyllum despite a marked decline in seed production and increase in population - . isolation approaching its periphery. C. heterophyllum exhibits almost randomised geographical structure of genetic variation. The lack of agreement between patterns of reproductive potential and population frequency and population genetic structure suggests that contemporary patterns of population distribution and reproduction may be inadequate for indicating patterns of population genetic structure within a species. Interspecific differences in post-glacial history may be important in explaining this disparity.

Cephalopod populations typically display life-history traits such as semelparity, fast growth, and rapid response to environmental variation. The short lifespan of most squid species means that populations typically consist of single non-overlapping generations; the success of future generations therefore depends upon the ability of present generations to produce viable offspring. Pronounced inter-annual fluctuations in cephalopod population sizes reflect, at least in part, variability during the embryonic, hatchling and juvenile phases. As post-hatch survival is critically dependent upon the successful capture and consumption of zooplanktonic prey, variability in hatchling morphology (e.g. size, shape, presence of abnormality) and physiology (e.g. thermal tolerance) are likely to exert significant influence upon survival. This thesis investigates embryonic variability in two temperate loliginid squid: the Northern Hemisphere Loligo forbesi Steenstrup 1856 and the Southern Hemisphere Sepioteuthis australis Quoy and Gimard 1832. Developmental variability in L. forbesi and S. australis largely manifests via chromatophore pattern. The plasticity and thermal sensitivity of chromatophore characters exceed those of standard morphological characters (e.g. body shape and size). Elevation of incubation temperature is associated with reduced chromatophore number and heightened pattern asymmetry. Correlation between temperature and hatchling phenotype is sufficiently strong to permit estimation of mean thermal history from measure of multiple chromatophore and morphological characters. Increased water temperature is associated with increased frequency of morphological abnormality. In situ assessment of embryonic development in S. australis indicates ~89% egg viability within egg strands. Significant intra-seasonal differences in incidence of mortality and abnormality appear to reflect changes in environmental conditions. Embryos reared under fluctuating (field) thermal conditions grow faster than those reared under stable (aquaria) thermal conditions. Despite variation in size-at-hatch, no concomitant differences are observed in mantle muscle structure. The results of this thesis indicate no significant relationship between hatchling phenotype and underlying physiological processes (i.e. plasticity). I discuss the idea that quantification of embryonic development in cephalopods has relevance to both fisheries management and biomonitoring.

No description available.

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 53-58). Also available on the World Wide Web.

Adult dusky Canada geese (Branta canadensis occidentalis Baird) were banded with plastic neck bands and observed on the winter range during 1985-92. Annual survival rates of adult geese estimated from observation data ranged from 76% to 85%. A model of Canada goose population dynamics was developed to illustrate relationships between survival rates, harvest regulations, and recruitment parameters and to predict trends in population size. Model simulations using recent estimates of survival and recruitment indicated that without significant increases in recruitment, survival rates must remain at or above present levels for the dusky Canada goose population to maintain itself. Observations of geese banded with tarsal and neck bands were used to estimate within-year survival rates and rates of neck band loss during 1990-92. Average monthly survival was 97% and was not significantly different among harvest and nonharvest periods (X��, P = 0.3882). Neck band retention rates were 100% and 98% the first and second year after banding, respectively, for male and female geese. Resighting probabilities for neck and tarsal bands were significantly lower for female than for male geese (X��, P < 0.020). Midwinter population size was estimated using neck band observations and a capture-resighting model. Dusky Canada goose population estimates ranged from 12,400 to 19,800 during 1990-92. Population estimates generally agreed with the U.S. Fish and Wildlife Service midwinter inventory during this period. Subflocks of wintering dusky Canada geese were identified using a clustering algorithm and the number of weeks neck banded geese were observed in regions of the winter range. Over 65% of geese in subflocks affiliated with the northern and southern regions of the winter range were never observed outside their region of affiliation. Geese affiliated with the middle regions of the winter range exhibited greater movement, as most were seen at least once outside their region of affiliation. Although large groups could be identified based on regional use patterns, associations between group members could only be demonstrated for small groups of [less than or equal to] 10 geese and adult pairs. / Graduation date: 1993

Thesis (M.S.)--Oregon State University, 1983. / Typescript (photocopy). Includes bibliographical references (leaves 46-51). Also available via the World Wide Web.

Thesis (Ph. D.)--University of Washington, 1984. / Vita. Bibliography: leaves [167]-177.

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 157-172).

Thèse de doctorat : Biologie forestière : Orléans : 2009. / Titre provenant de l'écran-titre.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 66-71). Also available on the World Wide Web.