Graduate Theses & Dissertations

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cis-Cytokinins from the tRNA-degradation pathway impact the phenotype and metabolome of Arabidopsis thaliana
Cis-isomers of the cytokinin plant hormone family are thought to have low activity or impact on plant growth and development. Mutants with independent silencing of the pathway leading to cis-CK (cis-cytokinin) were investigated at the phenotype and metabolite levels. Phenotypic deviations were noted in trichome development, fresh weight, rosette diameter, number of non-rosette leaves, shoot height, delayed flowering, flower number, and carotenoids. Exploratory metabolomic analysis detected a number of metabolite features that have been associated with CK, auxin, and ABA (abscisic acid) activity. Evidence from both phenotype and metabolomic analysis support the hypothesis that cis-CK production is biologically important for plant growth and development. Author Keywords: arabidopsis, cytokinin, IPT, metabolmics
cascading effects of risk in the wild
Predation risk can elicit a range of responses in prey, but to date little is known about breadth of potential responses that may arise under realistic field conditions and how such responses are linked, leaving a fragmented picture of risk-related consequences on individuals. We increased predation risk in free-ranging snowshoe hares (Lepus americanus) during two consecutive summers by simulating natural chases using a model predator (i.e., domestic dog), and monitored hare stress physiology, energy expenditure, behaviour, condition, and habitat use. We show that higher levels of risk elicited marked changes in physiological stress metrics including sustained high levels of free plasma cortisol which had cascading effects on glucose, and immunology, but not condition. Risk-augmented hares also had lowered daily energy expenditure, spent more time foraging, and decreased rest, vigilance, and travel. It is possible that these alterations allowed risk-exposed hares to increase their condition at the same rate as controls. Additionally, risk-augmented hares selected, had high fidelity to, and were more mobile in structurally dense habitat (i.e., shrubs) which provided them additional cover from predators. They also used more open habitat (i.e., conifer) differently based on locale within the home range, using familiar conifer areas within cores for rest while moving through unfamiliar conifer areas in the periphery. Overall, these findings show that prey can have a multi-faceted, highly plastic response in the face of risk and can mitigate the effects of their stress physiology given the right environmental conditions. Author Keywords: behaviour, condition, daily energy expenditure, predator-prey interactions, snowshoe hare, stress physiology
Youth Justice in Canada
Strategies to reduce youth crime have been extensively researched and custody is not found to be effective. In the past, custody was a frequently used sentence, and while under the YOA the number of youth in custody was four times higher than that of adults in Canada. The use of custody sentences in Ontario has decreased in recent years, however; it remains above the Canadian average. Currently, alternatives to custody are also being implemented. This study aimed to gather lived experiences of those with firsthand experience in the youth justice system (offenders and staff). These individuals have working knowledge of effective practices for reducing recidivism. Eighteen semi-structured interviews were conducted. Interviews were coded and analysed using Interpretive Phenomenological Analysis. A number of themes emerged, including various views on the benefits of custody, the importance of relationships, challenges of the job and the need for increased focus on prevention. Author Keywords: Interpretive Phenomenology, Rehabilitation, Treatment, Youth Justice
Yearly variation in fall movements of adult female American black bears (Ursus americanus) in central Ontario, Canada
I investigated site fidelity and habitat selection of American black bears (Ursus americanus) from 15 GPS-collared adult females in central Ontario, Canada over nine years. I used generalized linear mixed models to determine the factors affecting between-year variation in fall fidelity and the habitat selection in movement paths. I assessed second and third-order habitat preference by female bears moving between seasonal home ranges. I found that 66% of bears returned to the same fall area between years, expressed as range overlap, influenced negatively by whether they had cubs. When moving between seasonal ranges, bears selected for mixedwood, hardwood and wetlands cover but selected ridge tops over other habitat features at both scales. With increases in climatic uncertainty and habitat fragmentation, these results emphasize the need for wildlife management to consider annual variation in seasonal movements and habitat use by wide-ranging, opportunistic animals. Author Keywords: American black bear, Habitat Selection, Logistic Regression, Site Fidelity
Women's Lived Experience of Risk in Pregnancy
Cardiovascular disease (CVD) prevention, treatment and outcomes in women remain largely inequitable globally. Unique sex-specific stages of life, including pregnancy conditions, and their influence on cardiac risk is a growing area of research (Norris et al., 2020). For example, preeclampsia is strongly associated with CVD risk. This connection has led to prevention interventions such as postpartum risk clinics. Research to date on pregnancy and chronic disease is rooted in the medical paradigm of risk and lacks women’s lived experience. The present study qualitatively explored illness and risk perceptions of women with risky pregnancy conditions. Some participants felt self-blame for their conditions. Consequences and severity were focused on “baby first”, while maternal risk was viewed in the distant future. Aspects of the pregnancy experience, including prompt access to mental health support, was viewed as a “blessing in disguise”. Risks, such as lack of agency, and benefits of healthcare risk communication and intervention and implications for practice were also explored. Author Keywords: communication, critical, health care, phenomenology, pregnancy, risk
Women as Gifts and the Triple Hecate Myth in Shakespeare’s Troilus and Cressida, Antony and Cleopatra, and Cymbeline
ABSTRACT Women as Gifts and the Triple Hecate Myth in Shakespeare’s Troilus and Cressida, Antony and Cleopatra, and Cymbeline Women are placed into sexual roles by the patriarchal system in which we live. Gayle Rubin terms this a “sex/gender system” and explains that within this system women are exchanged as “gifts” between men to form kinship ties. The sexual roles this system creates are embodied in the “Triple Hecate myth.” Hecate was the goddess of witchcraft in Ancient Greece and was known to have three faces: Maiden, Nymph and Crone. The Maiden is in girlhood and the label is applied to any woman before she becomes sexually active. The Nymph is a sexually active woman who lives within the norms of society. A sexually active woman who lives outside those norms is a Whore. A Crone is a woman who has passed menopause. She is seen as either a wise elder or a wicked stepmother figure. In Shakespeare’s plays Troilus and Cressida, Antony and Cleopatra, and Cymbeline, the female protagonists Cleopatra, Imogen and Cressida are all trying to control their own destinies and rise above or manipulate this patriarchal system of control. These three women are travelling through the “Triple Hecate Myth.” Cleopatra begins a Whore and ends a Nymph, Imogen begins a Maiden and ends a Nymph, and Cressida begins a Maiden and ends a Whore. They each also problematize the “gift” exchange system either by attempting to self-exchange (Cleopatra and Imogen) or by being exchanged multiple times (Cressida). Keywords: William Shakespeare, Triple Hecate Myth, Gift Exchange, Gayle Rubin, Cymbeline, Troilus and Cressida, Antony and Cleopatra, Feminist Criticism, Classical Studies Author Keywords: Antony and Cleopatra, Cymbeline, Gayle Rubin, Shakespeare, Triple Hecate, Troilus and Cressida
Witches and Bawds as Elderly Women in England, 1680-1730
Many print sources from 1680 to 1730 depicted bawds and witches as figures of transgressive elderly femininity. They were often described as having roughly the same anti-social behaviour, age, and gender. Both witches and bawds were seen as seducing innocents into a life of sin, associating with the devil, and acting lustful and unmotherly. Furthermore, they were connected with Catholicism and were thought to unite sinners against English Protestant society. The physical descriptions of the witch and procuress also bore significant patterns in presenting deformity, disfigurement, smelliness, rottenness, and death, traits generally connected with elderly women. Though historians have recognized the tendency of the witch or bawd to be characterized as an old woman, none have conducted a systematic comparison of the two stereotypes. Such an analysis can offer insight about the social anxieties around aging femininity in this period. Author Keywords: bawd, cheap print, elderly women, old age, witch, witchcraft
Widespread changes in growth, diet and depth distribution of lake whitefish (Coregonus clupeaformis) in the Great Lakes are linked to invasive dreissenid mussels
Recent declines in growth and condition of Great Lakes' lake whitefish (Coregonus clupeaformis) have been linked to ecosystem-wide changes stemming from the invasion of dreissenid mussels. To test the influence of invasive mussels on this commercially important coregonid species, we collected archived scale samples from ten Great Lake locations and analyzed long-term changes in growth rates, delta 13C and delta 15N stable isotope ratios before and after mussel establishment. There was a decrease in pre-maturation growth after establishment in all four locations where we examined back-calculated growths. In six of the seven locations with dreissenid populations, a significant increase in delta 13C and a significant decrease in delta 15N was found. In dreissenid-absent locations of Lake Superior, we did not see changes in growth or isotope ratios indicative of a major regime shift. Observed shifts in isotopic signatures provide evidence for an increased reliance on nearshore food sources and shallower depth distribution as a result of dreissenids, which likely contributed to lowered growth of lake whitefish. Author Keywords: Diporeia, Dreissenids, food web, Great Lakes, invasive species, lake whitefish
Why not give up? A study on the role of resourcefulness in goal pursuit
Past research suggests that taking a process oriented approach, setting clear and concrete goals, and using both conscious planning and proactive coping are the best methods to be successful with goal pursuit. Also the literature has found that individuals scoring higher in general resourcefulness tend to be more successful at achieving goals than their less resourceful counterparts. My thesis looked at these goal pursuit behaviours under the lens of resourcefulness using a mixed methods approach. After completing Rosenbaum’s self-control scale (1980) assessing general resourcefulness, participants took part in a semi-structured interview asking them about a recent goal they had set and how they dealt with interfering obstacles. The hope was hearing differences about how highly and less resourceful people discuss their goals and setbacks would give a deeper understanding about the characteristics of success. The themes emerging from the interviews were: blame and excuses versus understanding and growth, internal versus external factors, living in the moment versus conscious planning and magical versus realistic thinking. In contrast to low-scoring participants, highly resourceful individuals grew from their setbacks, were internally driven, consciously planned, and thought realistically about their goals. Less resourceful individual, on the other hand blamed outside factors and made excuses, were only motivated externally, didn’t plan out their goals and believed their goals would just magically materialize over time. My discussion focuses on the ability to train lower resourceful individuals over longer interventions, and the applications of understanding and using resourcefulness as a lens in future studies. Author Keywords: Goal, Habits, Quitting, Resourcefulness, Self-Control, Success
Why do landowners restore wetlands? A case study from east central Ontario
Wetlands were once widespread in southern Ontario, but many have been drained through land use changes. Using a case study of twelve landowners in the Kawartha region, I explored motivations for restoring wetlands. Psychological research suggests that people who are more connected to nature and attached to place are more likely to behave sustainably. Results showed that having land available and receiving funding were necessary preconditions. Connectedness to nature and place attachment were motivations, as were personal benefits and having a supportive social community. Challenges included: the Permit to Take Water, paperwork and bureaucracy, delays and timing, and economic restrictions. Positive outcomes were: increased property value and crop productivity; personal enjoyment of wetlands; and improved wildlife habitat and water quality. Negative outcomes were: `nuisance' wildlife, trespassing, and a lack or excess of water. This is a novel study exploring nature connectedness, place attachment and wetland restoration qualitatively in southern Ontario. Author Keywords: agriculture, connection to nature, motivation, southern Ontario, stewardship, wetland restoration
Who Cares? Examining associations between caregiving sensitivity and parent-peer attachment
Although years of research have established that attachment representations are not consistently transmitted from parent to child (also known as the transmission gap), the reasons for this gap remain relatively unknown. This transmission gap exists between parents and peers as well. The purpose of this thesis was to examine the role of caregiving sensitivity in the relationship between parent attachment and peer attachment and to test if caregiving sensitivity helps explains the relationship between parent attachment and peer attachment. This study found support for the transmission of attachment from parent to peers, but not that caregiving sensitivity explains this transmission. Results indicate that parenting caregiving sensitivity questionnaires are inconsistent in assessing the construct of sensitivity. Parenting caregiving sensitivity questionnaires also do not measure the same concepts as peer caregiving sensitivity questionnaires. These findings suggest that assessing caregiving sensitivity in parents differently may help close the transmission gap. Author Keywords: attachment, caregiving, parenting, peer, sensitivity
White-Tailed Fear
The primary method used to maintain white-tailed deer (Odocoileus virginianus) populations at densities that are ecologically, economically, socially, and culturally sustainable is hunter harvest. This method considers only the removal of animals from the population (the direct effect) and does not conventionally consider the costs imposed on deer as they adopt hunter avoidance strategies (the risk effect). The impact of risk effects on prey can exceed that of direct effects and there is interest in applying this concept to wildlife management. Deer are potential candidates as they have demonstrated behavioural responses to hunters. I explored the potential of such a management practice by quantifying how human decisions around hunting create a landscape of fear for deer and how deer alter their space use and behaviour in response. I used a social survey to explore the attitudes of rural landowners in southern and eastern Ontario towards deer and deer hunting to understand why landowners limited hunting on their property. I used GPS tracking devices to quantify habitat selection by hunters and hunting dogs (Canis familiaris) to better understand the distribution of hunting effort across the landscape. I used GPS collars to quantify the habitat selection of deer as they responded to this hunting pressure. I used trail cameras to quantify a fine-scale behavioural response, vigilance, by deer in areas with and without hunting. Human actions created a highly heterogeneous landscape of fear for deer. Landowner decisions excluded hunters from over half of the rural and exurban landscape in southern and eastern Ontario, a pattern predicted by landowner hunting participation and not landcover composition. Hunter decisions on whether to hunt with or without dogs resulted in dramatically different distributions of hunting effort across the landscape. Deer showed a high degree of behavioural plasticity and, rather than adopting uniform hunter avoidance strategies, tailored their response to the local conditions. The incorporation of risk effects into white-tailed deer management is feasible and could be done by capitalizing on a better understanding of deer behaviour to improve current management practices or by designing targeted hunting practices to elicit a landscape of fear with specific management objectives. Author Keywords: Brownian bridge movement models, hunting, landscape of fear, resource utilization functions, risk effects, white-tailed deer

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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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1973 - 2033
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