Graduate Theses & Dissertations

Pages

Temporo-spatial patterns of occupation and density by an invasive fish in streams
Since its introduction to North America in the 1990s, the Round Goby has spread throughout the Great Lakes, inland through rivers and is now moving into small tributary streams, a new environment for this species in both its native and invaded ranges. I explored density and temporal occupation of Round Gobies in four small streams in two systems in south-central Ontario, Canada in order to determine what habitat variables are the best predictors of goby density. Two streams are tributaries of Lake Ontario and two are tributaries of the Otonabee River, and all of these streams have barriers preventing upstream migration. I found that occupation and density differed between the systems. In the Otonabee River system, Round Gobies occupy the streams year round and the most important factor determining adult density is distance from a barrier to upstream movement, with the entire stream occupied but density highest next to the barriers. In the Lake Ontario system, density is highest at mid-stream and Round Gobies appear to occupy these streams mainly from spring to fall. Adult density in Lake Ontario tributaries is highest in sites with a high percentage of cobble/boulder and low percentage of gravel substrate, while substrate is less important in Otonabee River tributaries. Occupation and density patterns may differ due to contrasting environmental conditions in the source environments and distance to the first barrier preventing upstream movement. This study shows diversity in invasion strategies, and provides insight into the occurrence and movement patterns of this species in small, tributary streams. Author Keywords: biological invasion, Generalised Additive Mixed Model, habitat, Neogobius melanostomus, Round Goby, stream
How Abiotic and Biotic Factors Can Alter the Competitive Landscape in an Aggressive Species Complex (Genus
Competition is known to impact population dynamics through both indirect and direct interactions, and direct interactions can often lead to injury in one or both parties. As such, response to injury through tissue regeneration can be important for surviving post-competitive interaction. However, the impacts of outside factors like temperature and genome size (e.g. polyploidy) are not well studied, especially in syntopic systems. We addressed this knowledge gap by comparing regeneration rates of diploid Ambystoma laterale and triploid unisexual Ambystoma at two ecologically-relevant temperatures. Environmental factors appeared to have stronger effects on regeneration than ploidy level, but overall mass was impacted more strongly by ploidy level. Interestingly, there was an interaction between temperature and time within unisexuals that was absent when comparing different ploidy levels, implying temperature has a more complex effect on polyploids. This study supports the hypothesis that polyploid organisms are better equipped to respond to shifts in their environments, which can give them a competitive advantage at the northern range limit of this species complex. Author Keywords: Ambystoma, Genome dosage, Hybrid vigor, Polyploidy, Thermal optimum, Tissue regeneration
What’s the trouble with women? Fostering female engagement in substance abuse programming
Although Canada’s healthcare system is designed for everyone to access services regardless of the person’s gender, age, or income, there are significant barriers for individuals accessing substance abuse services that live in areas outside of urban centres (Adbool, et al., 2017; Hardill, 2011). Women are particularly stigmatized by the lack of anonymity in smaller communities and often avoid engaging in substance abuse programs (Ashley, Marsden, & Thomas, 2003). The aim of the current thesis was to explore RedPath, a grassroots initiative in Port Hope, Ontario, geared to engaging individuals and encourage them to participate in substance abuse programming. This initiative employs a member from the community, called an Activator, who is tasked with engaging their peers. A qualitative study was conducted to explore the role of a hired RedPath Activator in facilitating access of female community members with substance abuse issues to services in the Port Hope community. Her role in supporting women was a specific interest, as the selection of a female Activator was a strategy to support the engagement of women to the program. The data was analyzed using a thematic content analysis approach. The most significant of these themes were (1) barriers and challenges in the community and (2) building trust to facilitate engagement and maintain attendance in the program. Author Keywords: activator, community, mental health, substance abuse, woman, women
Do birds of a feather flock together
Populations have long been delineated by physical barriers that appear to limit reproduction, yet increasingly genetic analysis reveal these delineations to be inaccurate. The eastern and mid-continent populations of sandhill cranes are expanding ranges which is leading to convergence and warrants investigation of the genetic structure between the two populations. Obtaining blood or tissue samples for population genetics analysis can be costly, logistically challenging, and may require permits as well as potential risk to the study species. Non-invasively collected genetic samples overcome these challenges, but present challenges in terms of obtaining high quality DNA for analysis. Therefore, methods that optimize the quality of non-invasive samples are necessary. In the following thesis, I examined factors affecting DNA quality and quantity obtained from shed feathers and examined population differentiation between eastern and mid-continent sandhill cranes. I found shed feathers are robust to environmental factors, but feather size should be prioritized to increase DNA quantity and quality. Further, I found little differentiation between eastern and mid-continent populations with evidence of high migration and isolation-by-distance. Thus, the two populations are not genetically discrete. I recommend future population models incorporate migration between populations to enhance our ability to successfully manage and reach conservation objectives. Author Keywords: feathers, genetic differentiation, non-invasive DNA, population genetics, population management, sandhill crane (Antigone canadensis)
Assessing Quality of Life for the Urban Inhabitants of Classical Angkor, Cambodia (c. 802-1432 CE)
This thesis examines the interrelationship of urban planning and population health at the site of Angkor (c. 802-1432 CE), the capital city of the Classical Khmer state, now found within modern-day Cambodia. The inhabitants of Angkor developed a settlement strategy that relied on the dispersal of water management features, rice fields, temples and residential areas, to best utilize the spread-out environmental resources of the surrounding monsoon-forest climate. Thus, the main question to be answered by this thesis is this: did the city-planning practice of dispersed, low-density agrarian urbanism promote resilience against the disease hazards associated with tropical environments? To answer this question, methods involved creating assessing environmental and socio-cultural factors which habituated the urban inhabitants of Angkor’s relationship to disease hazards. The results of this assessment demonstrate that it was not until the last stages of Angkor’s urban development, when non-farming members of the population were concentrated into the “core” area of temples within city, that the city’s inhabitants’ vulnerability to infectious disease increased. As the city took a more compact settlement form, it was not as environmentally compatible as the earlier dispersed pattern. Significantly, archaeological case studies such as this can illustrate the long-term development and end-result of urban planning to deal with disease hazards, both in terms of everyday occurrences, as well as during crisis events, which has important implications for contemporary research on environmental disasters today. Author Keywords: Adaptive Strategies, Mainland Southeast Asia, Pre-industrial Urbanization, Resilience, Tropical Diseases
role of corticosterone in breeding effort and reproductive success in tree swallows
Glucocorticoids (e.g., corticosterone (CORT)) are hypothesized to mediate decisions regarding reproductive investment during breeding, but the directionality of the relationship is not clear. The CORT-fitness hypothesis posits that high levels of CORT arise from challenging environmental conditions in which an individual will conserve resources for future reproduction or self-maintenance, and thus result in lower reproductive success (a negative relationship). In contrast, the CORT-adaptation hypothesis suggests that, during energetically demanding periods, CORT will mediate physiological or behavioural changes that result in increased reproductive investment and success (a positive relationship). Inconsistencies arise due to the various species and life-history stages studied, and the complex interactions between fitness and glucocorticoids. Using an experimental approach, I investigated the relationship between CORT and reproductive success by manipulating baseline CORT levels in female tree swallows Tachycineta bicolor prior to laying using silastic implants. Implants failed to raise CORT levels of females during either incubation or the nestling stage, and maternal treatment had no effect on indices of fitness at either stage. Using a correlative approach, partial support for the CORT-adaptation hypothesis was found: There was a positive relationship between CORT and hatching success. This only occurred when CORT was measured during incubation, when baseline CORT levels may stimulate increased reproductive effort and success. In contrast, during the nestling stage baseline CORT levels were not related to reproductive investment or success. Maternal CORT levels during incubation also did not influence nestling phenotype, although nestling stress CORT levels were higher in individuals that survived to fledging. In conclusion, CORT mediates reproductive effort and success during some breeding stages, but it is still unclear why this is the case and whether this same pattern will prevail in other contexts. Author Keywords: corticosterone, HPA axis, maternal effects, reproductive success, tree swallow
Exploring Kiki-Inoomgugaewin
This case study contributes to scholarship surrounding the national conversation on Indigenous language sustainability in North America. Much of this scholarship provides insight on structuring language programs and policies for youth, leaving a tremendous research gap regarding sociolinguistic and cultural research with youth. Youth appear disinterested or otherwise set apart in current research from the development of policies and curriculum concerned with heritage languages. Upon closer inspection; however, youth are engaged and using innovative and different tools than previous generations. This exploration is a foundational case study which builds upon research highlighting the nature of Indigenous language loss in the south as a time sensitive phenomenon as the application of cognitive imperialism and colonial tactics within mainstream schools continue to conceal a large scale cultural and linguistic genocide in Canada. Although Indigenous language loss may seem of concern to only small groups of linguists and dialectic communities, it should in fact concern anyone who cares about reconciliation or closing the tremendous gap in accessing equitable education. The preservation of Indigenous languages and knowledge systems should also be of interest to those parties who seek to comprehensively understand the Natural World and whom have a vested interest in the survival of the planet and protection of the enviroment. Because of these realities, the viewpoints and experiences of all concerned parties are essential. It follows then, that the youth perspective is significant. To address this gap, participatory narrative inquiry was used as a theoretical framework to conduct a foundational case study in which detailed consideration was given to exploring the lived narratives of three Anishnaabeg participants to establish the value of Indigenous youth voice in alternative forms of sociolinguistic and culturally sustainable language learning in the 21st century, and, to strengthen the argument that more research is needed in the field of first-person youth studies. The results of this case study will be useful, specifically, to localized communities of Anishnaabe youth with and for whom much of the research was conducted, and, more generally to youth resistance work focused on media and technology in globalized and contemporary language and cultural ecologies. Research outcomes indicated potential directions for future research in different contexts and localities by presenting commonalities within the fields of social and political engagement and their connection to language and new media in youth populations. It is hoped that this initial material pinpointing a research gap in Indigenous youth language studies will be used to investigate future research in this field. Author Keywords: Anishnaabe, Decolonization, Language, Sociolinguistics, Technology, Youth Studies
Emerging Dynamic Social Learning Theory of a Learning Community of Practice
In current knowledge-based economy, knowledge might be viewed as the most valuable organizational resource in sustaining any organization. Organizational knowledge originates from cognitive learning by individuals situated within organizations. In organizational learning, situated learning of knowledge by individuals is shared to create sustainable organizational competency. Yet, there is inadequate research to understand how situated learning operates as a social learning system within Community of Practice (‘CoP’). Through a case study of a multi-level, non-profit CoP in Ontario, Canada, this qualitative explanatory research contributes to the extant literature by building a unique theoretical framework that provides conceptual insights on linkages between organizational knowledge, social learning system, and organizational competency, in sustaining the organizational CoP. Using Straussian grounded theory methodology, qualitative primary data from in-depth interviews, participant observations, and documents were triangulated and analysed abductively to reveal an emerging dynamic knowledge-based social learning theory towards explaining how situated learning sustains this learning CoP. Author Keywords: Community of Practice, Grounded Theory, Organizational Knowledge, Organizational Learning, Organizational Sustainability, Situated Learning
Balance is key
While preferences for symmetry are seemingly universal, they can be seen at their most extreme among individuals high in trait incompleteness. As yet, it is unclear why incompleteness yields heightened symmetry preferences. Summerfeldt et al. (2015) speculated that individuals high in incompleteness may develop heightened preferences for symmetry due to its greater perceptual fluency. Accordingly, the aim of the present set of three experiments was to examine this relationship. Implicit preferences for symmetry were measured using a modified version of the Implicit Association Test (IAT) reported by Makin et al. (2012). Experiments 1 (N = 24) and 2 (N = 24) examined whether the general implicit preferences for symmetry and influence of perceptual fluency reported by Makin et al. (2012) extended to a within-subjects design. Experiment 3 (N = 86) examined whether trait incompleteness is related to greater implicit preferences for symmetric stimuli, and whether perceptual fluency affects this association. Results showed that incompleteness and implicit preferences were related, and that incompleteness-related differences in preferences were eliminated when the patterns were equally perceptually fluent, supporting the idea that incompleteness-related preferences for symmetry are linked to perceptual fluency. Implications of these findings are discussed. Author Keywords:
Relationship Between Precarious Employment, Behaviour Addictions and Substance Use Among Canadian Young Adults
This thesis utilized a unique data-set, the Quinte Longitudinal Survey, to explore relationships among precarious employment and a range of mental health problems in a representative sample of Ontario young adults. Study 1 focused on various behavioural addictions (such as problem gambling, video gaming, internet use, exercise, compulsive shopping, and sex) and precarious employment. The results showed that precariously employed men were preoccupied with gambling and sex while their female counterparts preferred shopping. Gambling and excessive shopping diminished over time while excessive sexual practices increased. Study 2 focused on the association between precarious employment and substance abuse (such as tobacco, alcohol, cannabis, hallucinogens, stimulants, and other substances). The results showed that men used cannabis more than women, and the non-precarious employed group abused alcohol more than individuals in the precarious group. This research has implications for both health care professionals and intervention program developers when working with young adults in precarious jobs. Author Keywords: Behaviour Addictions, Precarious Employment, Substance Abuse, Young Adults
Exploring the Scalability of Deep Learning on GPU Clusters
In recent years, we have observed an unprecedented rise in popularity of AI-powered systems. They have become ubiquitous in modern life, being used by countless people every day. Many of these AI systems are powered, entirely or partially, by deep learning models. From language translation to image recognition, deep learning models are being used to build systems with unprecedented accuracy. The primary downside, is the significant time required to train the models. Fortunately, the time needed for training the models is reduced through the use of GPUs rather than CPUs. However, with model complexity ever increasing, training times even with GPUs are on the rise. One possible solution to ever-increasing training times is to use parallelization to enable the distributed training of models on GPU clusters. This thesis investigates how to utilise clusters of GPU-accelerated nodes to achieve the best scalability possible, thus minimising model training times. Author Keywords: Compute Canada, Deep Learning, Distributed Computing, Horovod, Parallel Computing, TensorFlow
Risk of Mortality for the Semipalmated Plover (Charadrius semipalmatus) Throughout Its Life Cycle
Three long-term mark and recapture/resight data sets of individually marked Semipalmated Plovers (Charadrius semipalmatus) were analyzed using Cormack-Jolly- Seber models. Data came from two breeding populations (Churchill, Manitoba, Canada, n=982, and Egg Island, Alaska, USA, n=84) and one overwintering population (Cumberland Island, Georgia, USA, n=62). For Alaska and Georgia, time-invariant models were best-supported, giving annual survival estimates of 0.67 (95%C.I.: 0.58- 0.76) and 0.59 (95%C.I.: 0.49-0.67) respectively. Data from Manitoba supported a timedependent model: survival estimates varied from 1.00 to 0.36, with lowest estimates from recent years, supporting observations of local population decline. Seasonal survival analysis of the Georgia population indicated lower mortality during winter (monthly Φoverwinter: 0.959, 95%CI: 0.871-0.988; for 6 month period Φoverwinter: 0.780 (0.440-0.929)) than during combined breeding and migratory periods (monthly ΦBreeding+Migration: 0.879 (0.825-0.918); for 8 month ΦBreeding+Migration: 0356 (0.215-0.504)). I recommend, based on high resight rates, continued monitoring of survival of wintering populations, to determine potential range-wide population declines. Keywords: survival, longevity, mortality, shorebird, overwinter, breeding, migration, life cycle Author Keywords: life cycle, longevity, mortality, non-breeding, shorebird, survival

Pages

Search Our Digital Collections

Query

Enabled Filters

  • (-) ≠ Reid
  • (-) ≠ Doctor of Philosophy
  • (-) ≠ Environmental studies

Filter Results

Date

1979 - 2029
(decades)
Specify date range: Show
Format: 2019/11/12

Author Last Name

Show more

Last Name (Other)

Show more