Graduate Theses & Dissertations

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Neonatal Environment Influences Behavioural and Physiological Reactivity to Stressors, and Mammary Gland Development in BALB/c Mice
Using rodent models, it is possible to study the behavioural and physiological outcomes of early life stress and the influences on normal mammary gland development and carcinogenic risk. Results demonstrate that the experience of three weeks of prolonged maternal separation (LMS; 4 hrs/day) increased the susceptibility of adult, but not pubertal, female BALB/c mice to engage in higher levels of depressive-related immobility behaviour and lower levels of active floating (a suggested adaptive coping behaviour) in the acute forced swim test, than offspring that experienced three weeks of brief separation (BMS; 15 min/day) events. Despite the increased immobility behaviour, adult LMS female offspring demonstrated lower basal corticosterone levels relative to BMS females. However, the experience of chronic early-life stress, regardless of the length, results in greater changes between non-stressed and stressed corticosterone levels (i.e. stressor reactivity) in adult females compared to their male counterparts. These changes were associated with decreased glucocorticoid receptor and coactivator-associated arginine methyltransferase 1 protein expression in mammary gland of female LMS mice at young adulthood, highlighting potential mechanisms underlying their heightened risk of mammary tumourigenesis. These data suggest that early life environments can induce behavioural and physiological alterations observed in adulthood, which may have an influence on the likelihood of malignancies developing in the breast. Author Keywords: coping, early life stress, mammary gland development, mother-infant interactions, steroid receptors, stressor reactivity
Dimensions of socio-cultural sustainability
Social and cultural sustainability is increasingly discussed in a variety of disciplines and in the growing body of sustainability literature. However there is a lack of clarity in how the concept is defined and poor understanding as to how it relates to other aspects of sustainability. To address this issue, this research explored current definitions and representations of socio-cultural sustainability in the literature and community perspectives on this topic through a case study in Hopedale, Nunatsiavut, Labrador. This research identifies gaps in current understandings of this concept, as well as differences between community and academic perspectives. Case study results emphasized the importance of strong social relationships, cultural identity, and connection to place as central elements of socio-cultural sustainability in a northern, Indigenous context. These findings are valuable for policy and decision makers, regarding approaches to community planning and supporting the social and cultural aspects of sustainability. Author Keywords: cultural sustainability, Hopedale, Inuit, Nunatsiavut, social sustainability, socio-cultural sustainability
Evaluating the effects of landscape structure on genetic differentiation and diversity
The structure and composition of the landscape can facilitate or impede gene flow, which can have important consequences because genetically isolated groups of individuals may be prone to inbreeding depression and possible extinction. My dissertation examines how landscape structure influences spatial patterns of genetic differentiation and diversity of American marten (Martes americana) and Canada lynx (Lynx canadensis) in Ontario, Canada, and provides methodological advances useful for landscape geneticists. First, I identified the effects of map boundaries on estimates of landscape resistance, and proposed a solution to the bias: a buffer around the map boundary. Second, I assessed the sensitivity of a network-based estimate of genetic distance, conditional genetic distance, to incomplete sampling. I then used these landscape genetic tools in a pairwise, distance-based analysis of 653 martens genotyped at 12 microsatellite loci. I evaluated whether forest management in Ontario has influenced the genetic structure of martens. Although forest management practices had some impact, isolation by distance best described marten gene flow. Our results suggest that managed forests in Ontario are well connected for marten and do not impede marten gene flow. Finally, I used a site-based analysis of 702 lynx genotyped at 14 microsatellite loci to investigate spatial patterns of genetic diversity and differentiation at the trailing (contracting) edge of the lynx distribution in Ontario. I analyzed harvest records and found that the southern edge of lynx range has contracted by >175 km since the 1970s. I also found that neutral genetic diversity decreased towards the trailing edge, whereas genetic differentiation increased. Furthermore, I found strong correlations between gradients of lynx genetic structure and gradients of climate and land cover in Ontario. My findings suggest that increases in winter air temperature, decreases in snow depth, and loss of suitable habitat will result in further loss of genetic diversity in peripheral populations of lynx. Consequently, the adaptive potential of lynx populations on the southern range periphery could decline. In conclusion, my dissertation demonstrates the varying influences that contemporary landscape structure and climate gradients can have on genetic diversity and differentiation of different species. Author Keywords: Circuitscape, genetic network, landscape genetics, Lynx canadensis, Martes americana, range shift
An Emprirical Investigation into the Relationship Between Education and Health
Health literature has long noted a positive correlation between health and levels of education. Two competing theories have been advanced to explain this phenomenon: (1) education "causes" health by allowing individuals to process complex information and act on it; and, (2) education and health are merely correlated through some third underlying characteristic. Determining which of these two theories is correct is of importance to public policy. But that task is empirically difficult because, from the standard, static perspective, the theories are observationally equivalent. We exploit a way in which the two theories have different implications regarding the sort of behaviour we should observe over time. We use smoking as a measure of health behaviour and find that smoking rates between "high" and "low" educated individuals expand when information is hard to process, and then contract as it becomes more easily processable. This approach is then repeated using physical activity as a measure of health-related behaviour to address limitations of the smoking model. Our novel approach to estimating the differences in the behavioural responses to changes in the processability of health-related information, across education groups, provides strong evidence in support of the view that education and health are causally linked. Author Keywords: applied statistics, education, health economics, public health, public policy, smoking
Selection on functional genes across a flying squirrel (genus Glaucomys) hybrid zone
While hybridization between distinct taxa can have undesirable implications, it can also result in increased genetic variability and potentially, the exchange of adaptive genes or traits. Adaptive variation acquired through introgressive hybridization may be particularly advantageous for species facing rapid environmental change. I investigated a novel, climate change-induced hybrid zone between two flying squirrel species: the southern (Glaucomys volans) and northern (G. sabrinus) flying squirrel. I was interested in the occurrence of hybridization and introgression, the type of selective pressures maintaining the hybrid zone and the potential for adaptive introgression. I found relatively low hybridization and introgression frequencies (1.7% and 2.9% of the population, respectively) and no evidence of selection on hybrids or backcrosses in particular environments. I conclude that the data are more consistent with a hybrid zone maintained by endogenous (environment-independent) selection. I tested for adaptive introgression using two functional genes: IGF-1 and CLOCK. I documented intermediate functional allele frequencies in backcrosses compared to parental populations, suggesting the alleles do not confer fitness advantages in backcrosses. Despite lack of evidence for current adaptive introgression, genetic admixture between G. volans and G. sabrinus may provide adaptive potential should these species face more rapid or drastic environmental change in the future. Author Keywords: adaptive introgression, flying squirrel, Glaucomys sabrinus, Glaucomys volans, hybridization, introgression
Longitudinal trends of benthic invertebrates in regulated rivers
The Serial Discontinuity Concept describes the downstream recovery of key biophysical variables below an impoundment. With the proliferation of hydropower dams to meet increasing societal demands, further refinement and understanding of the Serial Discontinuity Concept is needed to accurately predict downstream impacts and ensure the proper management of rivers. In this study, I examine SDC predictions on physical, chemical and biological recovery in regulated rivers providing evidence from 1) a comprehensive literature review and 2) a formal test using two regulated rivers in Northern Ontario. I specifically address how these changes are reflected in benthic invertebrate abundance, diversity, and community composition. The literature review and case studies support the predicted recovery of temperature, periphyton, substrate, and drift. In addition, the study suggests that two recovery gradients exist in regulated rivers: 1) a longer, thermal gradient taking up to hundreds of kilometres downstream; and 2) a shorter, resource subsidy gradient recovering within 1-4 km downstream of an impoundment. Total benthic invertebrate abundance varies considerably and depends on the degree of flow alteration and resource subsidies from the upstream reservoir. In contrast, benthic diversity is reduced below dams irrespective of dam location and operation with little recovery observed downstream. Contrary to SDC predictions, the longitudinal gradient in regulated rivers is not a compaction of functional changes seen over several stream orders in natural rivers but a response to dam design and reservoir conditions. Stoneflies and dragonflies are particularly sensitive to regulation while filter feeding invertebrates are enhanced. Ward and Stanford's (1983) Serial Discontinuity Concept is still a useful framework for testing hypotheses. Future studies should further expand the SDC through empirical estimation within the context of the landscape to gain a better scientific understanding of regulated river ecology. Author Keywords: benthic invertebrates, dams, longitudinal, recovery, River Continuum Concept, Serial Discontinuity Concept
Songs We Share (and the Records We Steal)
This thesis explores the rhetoric of theft imposed on online music by comparing file sharing to shoplifting. Since the litigation between the music industry and Napster, file sharing has been perceived, both by the entertainment industry and by a music listening public, as a criminal act. However, file sharing has more in common with home taping and music archives than it does with music shoplifting. It differs from theft in terms of law, motivation and publicness. In reviewing three histories -- a history of petty theft, a history of policing online music, and a history of shoplifting narratives in popular music culture -- the implications for the cultural production of popular music and popular music identity become apparent. In the end, file sharing links itself more to parody and the concept of fairness than it does to youth rebellion and therefore is unsuitable for sustaining a traditional music industry and the values it has formed with its public. Author Keywords: copyright, cultural production, file sharing, mp3, popular music, shoplifting
Spatial dynamics of pollination in dioecious Shepherdia canadensis in Yukon, Canada
Sexual reproduction in flowering plants depends on investment in reproduction, the mode of pollen transfer, the availabilities of nutrient resources and potential mates, and the spatial scales over which these processes take place. In this thesis, I studied the general reproductive biology of Shepherdia canadensis (L.) Nutt. (Elaeagnaceae) and the suite of pollinators that visit the plants in Ivvavik National Park, Yukon, Canada. Across ten sites, I found that S. canadensis females were larger than males, but males produced more flowers than females at most sites. Males typically occurred at higher frequencies than females with the average male to female sex ratio being 1.19 ± 0.08 (mean ± SE, n = 10 sites). Both shrub size and flower production were significantly influenced by interactions between soil nitrogen and sex. Insect visitors to S. canadensis flowers were primarily ants and flower flies (Syrphidae), but exclusion experiments indicated that visitation by flying insects yielded greater fruit production than visitation by crawling insects. I found that fruit set was limited by the density of males within populations, but only over small distances (4-6 m). This is the first study to demonstrate that female reproductive success of a generalist-pollinated dioecious plant is limited by the density of males over small spatial scales. Author Keywords: dioecy, pollinators, sex ratio, sexual dimorphism, Shepherdia canadensis
THE EFFECTS OF ROTATIONAL GRAZING AND HAY MANAGEMENT ON THE REPRODUCTIVE SUCCESS OF BOBOLINK AND EASTERN MEADOWLARK IN EASTERN ONTARIO
I investigated the impact of beef-cattle farm management on the reproductive success of Bobolink (Dolichonyx oryzivorus) and Eastern Meadowlark (Sturnella magna) within Eastern Ontario. I monitored rotational grazing management regimes and hay cut dates while assessing breeding phenology and reproductive success of Bobolinks and Eastern Meadowlarks. In pasture paddocks the major factor determining Bobolink reproductive success was the date that cattle entered a paddock to graze, with earlier entries resulting in lower reproductive success. On a landscape scale, within a series of paddocks grazed by a single herd, as the number of paddocks grazed during the nesting season increased, the number of Bobolinks that reproduced successfully decreased. Experimental quantification of trampling showed that cattle exposure to clay pigeon targets, regardless of stocking rates, resulted in the majority of targets being trampled. In hayfields associated with beef- cattle operations, grassland birds had a higher likelihood of success when cutting occurred after 4 July. The best method to improve the reproductive success of Bobolinks and Eastern Meadowlarks is to leave some hayfields and pasture paddocks undisturbed until nesting is complete. Author Keywords: Bobolink, Dolichonyx oryzivorus, farm management, hayfield, pasture, rotational grazing
USE OF SALIVARY CORTISOL TO EVALUATE THE INFLUENCE OF RIDES ON THE STRESS PHYSIOLOGY OF DROMEDARY CAMELS (CAMELUS DROMEDARIUS)
Many facilities attempt to alleviate the risk of chronic stress in captivity by providing environmental enrichment shown to minimize behavioural disorders and stress in several species. One potential form of enrichment used in zoos is training animals to perform rides for guests, however, the effect of this activity on the welfare of individual animals has never been examined. I validated the use of saliva for assessing stress in dromedary camels (Camelus dromedarius) an animal commonly used for rides. I then measured variation in salivary cortisol in four male camels during animal rides for guests at the Toronto Zoo. The camels were sampled during the ride season (from June to August) using four treatments: 1) in their pasture, 2) at the ride area not performing rides, 3) performing a low number of rides (n=50/day) and 4) performing a high number of rides (n=150/day). Furthermore, samples were taken before and after the ride season for comparison. There was a significant difference between the post-ride season treatment and the three treatments involving guest presence during the ride season (ride area, low rides, high rides. This indicates that performing rides is not a stressful experience based on the stress metrics I used, and suggests that rides may be a form of enrichment for dromedary camels. Author Keywords: ACTH challenge, animal welfare, camels, environmental enrichment, salivary cortisol, stress
Sinaakssin (writing/picture)
Assimilative policies limit and disrupt the inclusion of Aboriginal values in most Aboriginal services today. This art-based, qualitative research study approaches that issue, and using symbolism and story a sample scenario was created to demonstrate the impact of assimilative policy on Aboriginal service delivery in a storyboard format. The storyboard was then presented to four traditional thinkers who contemplated the issues therein, and as they deconstructed, considered, and conferred they resolved the matter and produced four distinct models. Imagery is relied on as a traditional means of communication to capture and convey the research issue as a painted story. This research tested the viability of using imagery as a storyboard methodology for solving social issues. By using this approach this dissertation sought to answer the question, does Indigenous knowledge have the power to change the systemic structures that surround our services. For the analysis, did the three Indigenous knowledge paradigms effectively assist in determining the nature of the Indigenous knowledge applied? Author Keywords: collective community subjectivity, Indigenous methodology, paradigms, story, symbolic communication, symbolic representation
Pausing Encounters with Autism and Its Unruly Representation
This dissertation seeks to explore and understand how autism, asperger and the autistic spectrum is represented in Canadian culture. Acknowledging the role of films, television, literature and print media in the construction of autism in the consciousness of the Canadian public, this project seeks to critique representations of autism on the grounds that these representations have an ethical responsibility to autistic individuals and those who share their lives. This project raises questions about how autism is constructed in formal and popular texts; explores retrospective diagnosis and labelling in biography and fiction; questions the use of autism and Asperger's as metaphor for contemporary technology culture; examines autistic characterization in fiction; and argues that representations of autism need to be hospitable to autistic culture and difference. In carrying out this critique this project proposes and enacts a new interdisciplinary methodology for academic disability study that brings the academic researcher in contact with the perspectives of non-academic audiences working in the same subject area, and practices this approach through an unconventional focus group collaboration. Acknowledging the contribution of disability studies approaches to representation, this project will also challenge these methodologies on the grounds that the diverse voices of audiences are, at times, absent from discourse focused research. Chapter One offers an explanation of disability studies scholarship and the history of autism as a category of disability and difference. Chapter Two looks at how disability and specifically autistic representations have been understood academically and introduces the rationale and experiences of the focus group project. Chapter Three explores retrospective, biographical diagnosis, the role of autism as technological metaphor, and contemporary biography. Chapter Four looks at the construction of autistic characters in Canadian literature and film. Chapter Five interrogates documentary and news media responses to autism and the construction of autism as Canadian health crisis, and also explores how discourses that surround autism are implicated in interventions and therapeutic approaches to autistic individuals. Key Terms Autism; Autistic Spectrum; Asperger; Disability; Representation; Media; Interdisciplinary Research; Focus Group; Retrospective Diagnosis; Biography; Academic Method; Academic and Representational Responsibility; Literature; Film; Diagnosis; Disability Studies; Therapy Author Keywords: Academic Method, Autism Spectrum, Biography, Disability, Interdisciplinary Research, Representation

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Graduate student theses produced at Trent University. You may also browse theses and dissertations by year, program, or author.

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1974 - 2024
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