Graduate Theses & Dissertations

Pages

Assessing the population genetic structure of the endangered Cucumber tree (Magnolia acuminata) in southwestern Ontario using nuclear and chloroplast genetic markers.
Magnolia acuminata (Cucumber tree) is the only native Magnolia in Canada, where it is both federally and provincially listed as endangered.Magnolia acuminata in Canada can be found inhabiting pockets of Carolinian forest within Norfolk and Niagara regions of southwestern Ontario. Using a combination of nuclear and chloroplast markers, this study assessed the genetic diversity and differentiation of M. acuminata in Canada, compared to samples from the core distribution of this species across the United States. Analyses revealed evidence of barriers to dispersal and gene flow among Ontario populations, although genetic diversity remains high and is in fact comparable to levels of diversity estimated across the much broader range of M. acuminata in the USA. When examining temporal differences in genetic diversity, our study found that seedlings were far fewer than mature trees in Ontario, and in one site in particular, diversity was lower in seedlings than that of the adult trees. This study raises concern regarding the future viability of M. acuminata in Ontario, and conservation managers should factor in the need to maintain genetic diversity in young trees for the long-term sustainability of M. acuminata in Ontario. Author Keywords: conservation genetics, cpDNA, forest fragmentation, Magnolia acuminata, microsatellites, population genetic structure
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
CO2 dynamics of tundra ponds in the low-Arctic Northwest Territories, Canada
Extensive research has gone into measuring changes to the carbon storage capacity of Arctic terrestrial environments as well as large water bodies in order to determine a carbon budget for many regions across the Arctic. Inland Arctic waters such as small lakes and ponds are often excluded from these carbon budgets, however a handful of studies have demonstrated that they can often be significant sources of carbon to the atmosphere. This study investigated the CO2 cycling of tundra ponds in the Daring Lake area, Northwest Territories, Canada (64°52'N, 111°35'W), to determine the role ponds have in the local carbon cycle. Floating chambers, nondispersive infrared (NDIR) sensors and headspace samples were used to estimate carbon fluxes from four selected local ponds. Multiple environmental, chemical and meteorological parameters were also monitored for the duration of the study, which took place during the snow free season of 2013. Average CO2 emissions for the two-month growing season ranged from approximately -0.0035 g CO2-C m-2 d-1 to 0.12 g CO2-C m-2 d-1. The losses of CO2 from the water bodies in the Daring Lake area were approximately 2-7% of the CO2 uptake over vegetated terrestrial tundra during the same two-month period. Results from this study indicated that the production of CO2 in tundra ponds was positively influenced by both increases in air temperature, and the delivery of carbon from their catchments. The relationship found between temperature and carbon emissions suggests that warming Arctic temperatures have the potential to increase carbon emissions from ponds in the future. The findings in this study did not include ebullition gas emissions nor plant mediated transport, therefore these findings are likely underestimates of the total carbon emissions from water bodies in the Daring Lake area. This study emphasizes the need for more research on inland waters in order to improve our understanding of the total impact these waters may have on the Arctic's atmospheric CO2 concentrations now and in the future. Author Keywords: Arctic, Arctic Ponds, Carbon dioxide, Carbon Fluxes, Climate Change, NDIR sensor
Help Wanted
The purpose of this thesis was to explore the role of attachment in university students’ help-seeking process using both a cross-sectional and mixed methods study. In the cross-sectional study, I explored whether help-seeking attitudes mediated the relationship between attachment and help-seeking behaviour. As expected, the relationship between secure and preoccupied attachment and greater help-seeking behaviour from both informal and self-help sources was partially mediated by positive attitudes toward seeking non-professional personal help. However, unexpectedly, attitudes toward professional psychological help did not mediate the relationship between attachment and formal help-seeking behaviour. In the mixed-methods study, secure students reported positive help-seeking experiences and discussed facilitators of help-seeking. On the other hand, fearful and dismissing students reported more negative help-seeking experiences and discussed barriers to help-seeking. Discussion of findings focus on how university staff can use attachment theory to develop interventions to increase student help-seeking. Author Keywords: Attachment, attitudes, Help-seeking, Relationships, Transitions, University students
Nietzsche and Deleuze
Gilles Deleuze claims that understanding the eternal recurrence as a recurrence of the same is a misreading of Friedrich Nietzsche, yet, this assertion is not supported by Nietzsche’s texts. In all instances where Nietzsche describes the eternal recurrence, he emphasizes that it is one of the same events. One’s willingness to love one’s fate and to will the eternal recurrence of the same represents the psychological state of the Overman and his achievement of joyousness. However, this is at odds with Deleuze and Felix Guattari’s conception of the nomad. Consequently, the nomad and the Overman are not congruous at all. Rather, the nomad is Nietzsche’s lion. The eternal return of the different then describes the psychological state of the lion as a precursor to the psychological state of the Overman. The lion cannot will the eternal recurrence of the same; he must will the eternal recurrence of the different. When the lion becomes the child, he has the psychological perspective within which to will the eternal recurrence of the same. It is in this sense that Nietzsche and Deleuze’s versions of the eternal recurrence are not antithetical – they are complementary and represent a progression of psychological thought. Author Keywords: Eternal Recurrence, Friedrich Nietzsche, Gilles Deleuze, Nihilism, Nomad, Overman
SPAF-network with Saturating Pretraining Neurons
In this work, various aspects of neural networks, pre-trained with denoising autoencoders (DAE) are explored. To saturate neurons more quickly for feature learning in DAE, an activation function that offers higher gradients is introduced. Moreover, the introduction of sparsity functions applied to the hidden layer representations is studied. More importantly, a technique that swaps the activation functions of fully trained DAE to logistic functions is studied, networks trained using this technique are reffered to as SPAF-networks. For evaluation, the popular MNIST dataset as well as all \(3\) sub-datasets of the Chars74k dataset are used for classification purposes. The SPAF-network is also analyzed for the features it learns with a logistic, ReLU and a custom activation function. Lastly future roadmap is proposed for enhancements to the SPAF-network. Author Keywords: Artificial Neural Network, AutoEncoder, Machine Learning, Neural Networks, SPAF network, Unsupervised Learning
regional comparison of the structure and function of benthic macroinvertebrate communities within Precambrian Shield and St. Lawrence lowland lakes in south-central Ontario
Benthic macroinvertebrtes (BMI) are functionally important in aquatic ecosystems; as such, knowledge of their community structure and function is critical for understanding these systems. BMI were sampled from ten lakes in each of two regions of south-central Ontario to investigate which chemical and physical variables could be shaping their community structure and function. Ten Precambrian Shield lakes in the Muskoka-Haliburton region, and ten St Lawrence lowland lakes in the Kawartha lakes region were sampled. These lakes are geologically and chemically distinct, creating natural chemical and physical gradients within and between both regions. Community function was assessed using stable isotope analysis to elucidate carbon transfer dynamics (δ13C) and food web interactions (δ15N). It was predicted that the BMI from Shield lakes would have a δ13C signature indicative of allochthonous carbon subsidies, whereas the lowland lake BMI signatures would reflect autochthonous production. Additionally, it was predicted that the food web length (measured in δ15N units) would be different in Shield and lowland lakes. Both of these predictions were supported; however, the data indicate that δ13C signatures are more likely influenced by catchment geology (represented by bicarbonate concentration) than the extent of allochthony. The best predictor of food web length was found to be region. To assess BMI community structure, taxonomic richness, %EPT (% Ephemeroptera, Plecoptera, Trichoptera; a water quality index), and distribution of functional feeding groups were examined. Based on chemistry it was expected that the Shield lakes would be more speciose, and of greater water quality (relatively lower nutrient levels). These predictions were rejected; since there were no significant regional differences in taxonomic richness or biologically inferred water quality (%EPT). However, sediment size was found to best explain the variability in both metrics, with greater richness and %EPT found at sites with medium and small substrates than those with large substrates. Significant regional differences were found in the distribution of functional feeding groups. Most notably, there were significantly greater proportions of scrapers and shredders in the lowland and Shield lakes, respectively. Based on the feeding mechanisms of these invertebrates it can be inferred that allochthonous subsidies are likely of greater importance to Shield lake BMI communities than those of the lowland lakes; supporting the carbon transfer prediction. These findings provide insight about the structure and function of BMI communities from two dominant lake types in Ontario, and could be useful when determining how future chemical and physical changes will impact these communities. Author Keywords: benthic macroinvertebrates, community function, community structure, Precambrian Shield, stable isotopes, St. Lawrence lowlands
Bank Swallow (Riparia riparia) Breeding in Aggregate Pits and Natural Habitats
I examined Bank Swallow (Riparia riparia) colony persistence and occupancy, in lakeshore, river and man-made aggregate pit habitat. Habitat persistence was highest on the lakeshore and lowest in aggregate pits, likely due to annual removal and relocation of aggregate resources. Bank Swallow colonies in aggregate pit sites were more likely to persist if a colony was larger or if burrows were located higher on the nesting face. I also compared nest productivity and health factors of Bank Swallows in lakeshore and aggregate pit habitats. While clutch size was the same in both habitat types, the number of fledglings from successfully hatched nests was significantly higher in aggregate pit sites than from lakeshore sites. Mass of fledgling Bank Swallows did not differ significantly between habitat types, however mass of adults from aggregate pits decreased significantly over the nesting season. Parasite loads on fledgling Bank Swallows were significantly lower in aggregate pits than in lakeshore sites. According to these indicators, aggregate pits appear to provide equivalent or higher quality habitat for Bank Swallows than the natural lakeshore sites, making them adequate and potentially key for this species’ recovery. Aggregate pit operators can manage for swallows by (1) creating longer, taller faces to attract birds and decrease predation, and (2) supplementing their habitat with water sources to encourage food availability. Author Keywords: Aerial insectivore, aggregate pits, Bank Swallow, colony persistence, ectoparasites, substitute habitat
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
Archaeological Investigation of the North Group at Pacbitun, Belize
This thesis reports on the 2010 excavations of the North Group and Eastern Court at the ancient Lowland Maya site of Pacbitun. It provides a construction history of the architecture and an analysis of associated artifacts, burials, and caches. The archaeological investigations demonstrate that the seven structures (Strs. 34-40) of this restricted access plazuela group were built in the Early Classic period, and renewed in the Late Classic period. Based on analyses of artifacts (ceramics and lithics), skeletal and faunal remains, and intra- and inter-site comparisons, the North Group functioned as a secondary elite domestic residential group. Reconstruction suggests that the inhabitants here were not commoners; instead, the occupants probably were related to the ruling elite of Pacbitun. Some of the evidence includes the central location and elevation of the North Group, the presence of red painted plaster surfacing, a burial with multiple ceramic musical instruments, and multiple dedicatory caches with exotic goods (e.g., marine shell, jadeite, "Charlie Chaplin" figures). Author Keywords: Ancient Maya, ceramic musical instruments, Charlie Chaplin figurines, Pacbitun, North Group, Eastern Court, Belize River Valley, Belize, restrictive access plazuela group, secondary elite
Determinants of Deviance
Background: Researchers have provided evidence that attachment may be independently linked to early adversity and criminal behaviour. In this study, I examined the combined associations among these variables in a student and community sample. Method: The first study consisted of undergraduate students (n = 590) who completed surveys to assess early adversity (Felitti, et al., 1988), attachment (Scharfe, 2016), and criminal behaviours. Participants were grouped based on their reports of adverse experiences and engagement in criminal behaviour. The second study was a replication of the first using a community sample (n = 294). Results: My hypotheses were partially supported, and my findings were consistent across Study 1 and Study 2. As I expected, there was a significant main effect for adversity when examining the mean scores of the attachment representations for attachment to mothers (Study 1 F (16, 1763.402) = 3.61, p < .001; Study 2 (F (16, 849.942) = 2.377, p = .002) and attachment to fathers (Study 1 F (16, 1763.402) = 4. 349, p < .001; Study 2 (F (16, 840.776) = 3.067 p < .001)). From examining the means, I concluded that participants who reported greater adversity reported higher insecure-avoidant and lower secure attachment to mothers and fathers. There were no significant main effects for criminal behaviour or significant interaction effects. Impact: To date, no study has explored all three variables explicitly. My findings are able to highlight the critical importance of secure attachment relationships and add further comprehension to exploring factors associated to criminal behaviour. Author Keywords: Attachment, Criminal Behaviour, Early Adversity
Using Fluorescent Carbon Dots for Biosensing Applications of Amino Acids
Amino acids make up proteins, which are the building blocks of life. A balance of amino acids is needed to maintain a healthy state. Tyrosine (Tyr) is synthesized from the metabolism of phenylalanine, which is an essential amino acid, meaning it can only be obtained from the diet. It is related to many metabolic and neurodegenerative diseases. Tyr can undergo post-translational modifications such as phosphorylation and nitration, which are implicated in cancer and nitrative stress, respectively. Although there are many methods to detect Tyr and its analogues, phosphotyrosine (pTyr) and nitrotyrosine (nTyr), these methods are time-consuming, involve expensive instruments and involve tedious process. This research proposes a new type of nanomaterials, carbon dots (CDs), to detect these amnio acids. Data indicate that CDs can be used to detect nTyr with a limit of detection of 34 μM in the linear range of 20 - 105 μM. The amenability of CD-nTyr assay was also tested in various biological matrices and biological molecules and was shown to be sensitive to nTyr. Nitration of Tyr was carried out in the presence of sodium nitrite and hydrogen peroxide catalyzed by either Cu(II) or Fe(III) to mimic biological reactions and CDs were tested as both inhibitors and indicators of Tyr nitration. Although CDs did not inhibit the nitration reaction of Tyr, they did not serve as indicators of Tyr nitration due to the quenching of CDs by the nitrating agents. This shows the importance of using CDs to detect nTyr and further use it for biological applications to detect diseased states. Author Keywords: amino acids, carbon dots, nanomaterials, sensor, spectroscopy, tyrosine

Pages

Search Our Digital Collections

Query

Enabled Filters

Filter Results

Date

1974 - 2024
(decades)
Specify date range: Show
Format: 2024/03/04