Graduate Theses & Dissertations


effects of heat dissipation capacity on avian physiology and behaviour
In endotherms, physiological functioning is optimized within a narrow range of tissue temperatures, meaning that the capacity to dissipate body heat is an important parameter for thermoregulation and organismal performance. Yet, experimental research has found mixed support for the importance of heat dissipation capacity as a constraint on reproductive performance. To investigate the effects of heat dissipation capacity on organismal performance, I experimentally manipulated heat dissipation capacity in free-living tree swallows, Tachycineta bicolor, by trimming feathers overlying the brood patch, and monitored parental provisioning performance, body temperature, and offspring growth. I found that individuals with an enhanced capacity to dissipate body heat (i.e., trimmed treatment) provisioned their offspring more frequently, and reared larger offspring that fledged more consistently. Although control birds typically reduced their nestling provisioning rate at the highest ambient temperatures to avoid overheating, at times they became hyperthermic. Additionally, I examined inter-individual variation in body temperature within each treatment, and discovered that body temperature is variable among all individuals. This variability is also consistent over time (i.e., is repeatable), irrespective of treatment. Further, I found that individuals consistently differed in how they adjusted their body temperature across ambient temperature, demonstrating that body temperature is a flexible and repeatable physiological trait. Finally, I used a bacterial endotoxin (lipopolysaccharide) to examine the regulation of body temperature of captive zebra finches (Taeniopygia guttata) during an immune challenge. Exposure to lipopolysaccharide induces sickness behaviours, and results in a fever, hypothermia, or a combination of the two, depending on species and dosage. I asked what the relative role of different regions of the body (bill, eye region, and leg) is in heat dissipation/retention during the sickness-induced body temperature response. I found that immune-challenged individuals modulated their subcutaneous temperature primarily through alterations in peripheral blood flow, particularly in the legs and feet, detectable as a drop in surface temperature. These results demonstrate that the importance of regional differences in regulating body temperature in different contexts. Taken together, my thesis demonstrates that heat dissipation capacity can affect performance and reproductive success in birds. Author Keywords: body temperature, heat dissipation, tree swallow, zebra finch
effects of environmental variables and dissolved organic matter characteristics on the diffusion coefficient of dissolved organic matter using diffusive gradients in thin films
The efficacy of the diffusive gradients in thin films (DGT) passive samplers to provide accurate measurements of free metal ions and those complexed with dissolved organic matter (DOM) was investigated. DOM controls the diffusive properties of DOM-complexed metal species in natural systems. Knowing the diffusion coeiffiecent (D) for DOM of different molecular weights (MW) and the major environmental variables influencing D is critical in developing the use of DGT passive samplers and understanding labile species. D and MW were determined for natural and standard DOM. No noticeable changes in DOM MW were observed during the diffusion process, suggesting that DOM remains intact following diffusion across the diffusive gel. Data analysis revealed that MW had the greatest influence on D, with a negative relationship between D and MW, except in tidal areas where ionic strength influence on D was significant. This study provides further characterization of the variables influencing D using the DGT technique. Author Keywords: Diffusion coefficient, Diffusive gradients in thin films, Dissolved organic matter, Flow field-flow fractionation, Principal Component Analysis, UV-Vis Spectroscopy
effects of Dissolved Organic Matter (DOM) sources on Pb2+, Zn2+ and Cd2+ binding
Metal binding to dissolved organic matter (DOM) determines metal speciation and strongly influences potential toxicity. The understanding of this process, however, is challenged by DOM source variation, which is not always considered by most existing metal speciation models. Source determines the molecular structure of DOM, including metal binding functional groups. This study has experimentally showed that the allochthonous-dominant DOM (i.e. more aromatic and humic) consistently has higher level of Pb binding than the autochthonous-dominant DOM (i.e. more aliphatic and proteinaceous) by more than two orders of magnitude. This source-discrimination, however, is less noticeable for Zn and Cd, although variation still exceeds a factor of four for both metals. The results indicate that metal binding is source-dependent, but the dependency is metal-specific. Accordingly, metal speciation models, such as the Windermere Humic Aqueous Model (WHAM), needs to consider DOM source variations. The WHAM input of active fraction of DOM participating in metal binding (f) is sensitive to DOM source. The commonly-used f = 0.65 substantially overestimated the Pb and Zn binding to autochthonous-dominant DOM, indicating f needs to be adjusted specifically. The optimal f value (fopt) linearly correlates with optical indexes, showing a potential to estimate fopt using simple absorbance and/or fluorescence measurements. Other DOM properties not optically-characterized may be also important to determine fopt, such as thiol, which shows strong affinity to most toxic metals and whose concentrations are appreciably high in natural waters (< 0.1 to 400 nmol L-1). Other analytical techniques rather than Cathodic Stripping Voltammetry (CSV) are required to accurately quantify thiol concentration for DOM with concentration > 1 mg L-1. To better explain the DOM-source effects, the conditional affinity spectrum (CAS) was calculated using a Fully Optimized ContinUous Spectrum (FOCUS) method. This method not only provides satisfactory goodness-of-fit, but also unique CAS solution. The allochthonous-dominant DOM consistently shows higher Pb affinity than autochthonous-dominant DOM. This source-discrimination is not clearly observed for Zn and Cd. Neither the variability of affinity nor capacity can be fully explained by the variability of individual DOM properties, indicating multiple properties may involve simultaneously. Together, the results help improve WHAM prediction of metal speciation, and consequently, benefit geochemical modelling of metal speciation, such as Biotic Ligand Model for predicting metal toxicity. Author Keywords: Dissolved organic matter, Metal binding, Source, Windermere Humic Aqueous Model
collaborative ecotoxicological risk assessment of in-place pollutants in Owen Sound Bay, Lake Huron within the Saugeen Ojibway Nation Territory
Owen Sound Bay, which is located within the traditional territory of the Saugeen Ojibway Nation (SON), is contaminated as a result of historical industrial and shipping activity. Gross contamination of the sediments in the inner part of the Bay (i.e., Owen Sound Harbour) includes high concentrations of polycyclic aromatic hydrocarbons (PAHs) and other organic compounds, as well as metals that may pose a risk to the SON fishery for lake whitefish (Coregonus clupeaformis). However, evaluating the environmental risks posed by contaminated sediments is a challenge, as these risks are dependent upon several factors and require multiple lines of evidence. Including Indigenous communities in environmental risk assessment and the management of those risks is vital for sustaining ecosystem integrity, as well as respecting Treaty Rights. In this study, a risk assessment framework was developed that included several risk assessment tools used in Western science and also encompassed the concerns and values of the SON, including the application of SON-ecological knowledge. Methods for risk evaluation included gathering lines of evidence though community workshops, as well as field sampling in the Bay to determine the concentrations of PAHs and other organic contaminants in sediments and in the water column. Laboratory studies of toxicity to early life stages of lake whitefish and Japanese medaka (Oryzias latipes) and sediment disturbance simulations to evaluate biological responses in juvenile lake whitefish were also completed as lines of evidence. The results indicate that leaving the harbour “as is” without a thorough analysis of remediation options fails to address the concerns of the people within the SON communities. Overall, this research demonstrated a successful process for developing a collaborative risk assessment framework that recognizes the sovereignty of Indigenous peoples and promotes Nation-to-Nation decision making. Author Keywords: biomarkers, Coregonus clupeaformis, Indigenous knowledge, polycyclic aromatic hydrocarbons, risk assessment, source tracking
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
Workplace Bullying in Ontario Healthcare Settings
This thesis builds on scholarship that highlights how expected gender roles serve to both normalize and obscure forms of violence and hostility in health care workplaces. An analysis of 25 labour arbitrations involving cases of bullying reveals how gender relations is a factor in these grievances and relevant policies in Ontario health care facilities. Reinforced by underlying expectations around women as nurturing and men as aggressive, responses to bullying are found to reflect and reproduce embedded gendered power inequalities in labour. While bullying in the workplace is often treated in policy discussions as an individual and identity-neutral phenomenon, this research provides evidence to the contrary. As a consequence, we must interrogate existing legislation and policies, asking how we can develop approaches that account for, respond to, and mitigate the causes of bullying rooted in unequal power relations, including gendered ones. Author Keywords: gender, health care, labour arbitration, policy, workplace bullying, workplace harassment
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


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Format: 2023/02/02