Graduate Theses & Dissertations

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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
Spatial and Temporal Variation in Peatland Geochemistry in Sudbury, Ontario, Canada
The damage to Sudbury's landscape from over a century of smelter and logging activity has been severe and impacts well documented. However, despite their abundance in the region, wetlands have received little attention. Recent studies have identified that nutrient limitation is as much a problem as metal toxicity and highlighted not only the importance of wetlands but also the need for more detailed studies examining the role of wetlands in the recovery of lakes. The objective of this work is to characterize the spatial and temporal variability in the geochemistry of 18 wetlands (poor fens) surrounding Sudbury, Ontario. Peat and water chemistry in the wetlands exhibited large spatial and temporal variability. Copper and Ni concentrations in surface peat decreased with distance from the largest smelter in the area, but water chemistry was also strongly influenced by natural factors such as climate, groundwater and peat carbon content. Redox processes contribute greatly to temporal variation in pore-water chemistry: the August and October campaigns were characterized by higher SO4, lower pH and higher concentrations of metals such as Ni, Cu and Mn compared with the May campaign. Other factors contributing to the temporal variability in pore water chemistry include DOC production, senescence and water source. Despite the large variability, soil-solution partitioning can be explained by pH alone for some metals. Modeling is significantly improved with the addition of other variables representing dissolved organic matter quality and quantity, sulphate concentration and hydrology. Author Keywords: metal contamination, metal mobility, organic matter quality, peatland geochemistry
Spatial Dynamics of Wind Pollination in Broadleaf Cattail (Typha latifolia)
Natural populations of flowering plants rarely have perfectly uniform distributions, so trends in pollen dispersal should affect the size of the pollination neighbourhood and influence mating opportunities. Here I used spatial analysis to determine the size of the pollination neighbourhood in a stand of the herbaceous, wind-pollinated plant (Typha latifolia; broad-leaved cattail) by evaluating patterns of pollen production and seed set by individual cattail shoots. I found a positive correlation between pollen production and seed set among near-neighbour shoots (i.e., within 4 m2 patches of the stand; Pearson's r = 0.235, p < 0.05, df = 77) that was not driven by a correlation between these variables within inflorescences (Pearson's r = 0.052, p > 0.45, df = 203). I also detected significant spatial autocorrelations in seed set over short distances (up to ~ 5 m) and a significant cross-correlation between pollen production and seed set over distances of < 1 m indicating that the majority of pollination events involve short distances. Patterns of pollen availability were simulated to explore the shape of the pollen dispersal curve. Simulated pollen availability fit actual patterns of seed set only under assumptions of highly restricted pollen dispersal. Together, these findings indicate that even though Typha latifolia produces copious amounts of pollen, the vast majority of pollen dispersal was highly localized to distances of ~ 1 m. Moreover, although Typha latifolia is self-compatible and has been described as largely selfing, my results are more consistent with the importance of pollen transfer between nearby inflorescences. Therefore, realized selfing rates of Typha latifolia should largely depend on the clonal structure of populations. Author Keywords: clonal structure, correlogram, dispersal curves, pollination, spatial analysis, Typha latifolia
Spatial Bestiary
In my Master’s thesis, I consider how the space of the animal laboratory shapes human-animal relationships, and how, in turn, these relations impact the laboratory, and more specifically, the spatially-bound practices that unfold in this space. I use the frameworks of biopolitics and animal geography, both of which help in illuminating the space of the lab as a site of power, within which human-animal agency becomes exercised. Alongside these analytics, I conducted participant interviews with individuals who work with animals in laboratories or settings similar to laboratories, which animate several themes that I locate at the intersection of biopolitics and animal geography. These themes include a discussion of human-animal relations of power, scientific biopower and scientific market economies, the animal-industrial complex, and the relationship between human binaries and their effects on spatiality. This project is as much about animal lives as it is about human lives. Author Keywords: agency, animal geography, biopower, human-animal relationships, spatiality, the animal laboratory
Sowing the seeds of Canada's future agroecological farm(er)s
There are many barriers facing new, sustainably-focused, agriculturalists in Canada including access to land, capital, markets and practical training. These challenges are compounded by the flawed but powerful figure of the industrial agriculture model, a rapidly aging farmer population, changing demographics, and subsequent loss of valuable, place-based agricultural knowledge. This thesis argues that there is a need for innovative formal education programs that combine traditional classroom with practical hands-on learning in collaboration with local experts. As such, this exploratory case study looks at how a farm incubator can function as a site for experiential education and a means of addressing some of the barriers to entry faced by new agroecological farmers. The findings show that those seeking experiential sustainable agriculture education benefit greatly from having a site, such as a farm incubator, to learn the skills that accompany their knowledge while building their agricultural community and increasing their confidence. Author Keywords: agroecology, experiential learning, farm incubators, social learning, sustainable agriculture and food systems education, transdsciplinary
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
Solving Differential and Integro-Differential Boundary Value Problems using a Numerical Sinc-Collocation Method Based on Derivative Interpolation
In this thesis, a new sinc-collocation method based upon derivative interpolation is developed for solving linear and nonlinear boundary value problems involving differential as well as integro-differential equations. The sinc-collocation method is chosen for its ease of implementation, exponential convergence of error, and ability to handle to singularities in the BVP. We present a unique method of treating boundary conditions and introduce the concept of the stretch factor into the conformal mappings of domains. The result is a method that achieves great accuracy while reducing computational cost. In most cases, the results from the method greatly exceed the published results of comparable methods in both accuracy and efficiency. The method is tested on the Blasius problem, the Lane-Emden problem and generalised to cover Fredholm-Volterra integro-differential problems. The results show that the sinc-collocation method with derivative interpolation is a viable and preferable method for solving nonlinear BVPs. Author Keywords: Blasius, Boundary Value Problem, Exponential convergence, Integro-differential, Nonlinear, Sinc
Soil mineralizable nitrogen as an indicator of soil nitrogen supply for grain corn in southwestern Ontario
Soil mineralizable nitrogen (N) is the main component of soil N supply in humid temperate regions and should be considered in N fertilizer recommendations. The objectives of this study were to determine the potentially mineralizable N parameters, and improve N fertilizer recommendations by evaluating a suite of soil N tests in southwestern Ontario. The study was conducted over the 2013 and 2014 growing seasons using 19 field sites across southwestern Ontario. The average potentially mineralizable N (N0) and readily mineralizable N (Pool I) were 147 mg kg-1 and 42 mg kg-1, respectively. Pool I was the only soil N test that successfully predicted RY in 2013. The PPNT and water soluble N (WSN) concentration (0-30cm depth) at planting were the best predictors of fertilizer N requirement when combing data from 2013 and 2014. When soils were categorized based on soil texture, the relationships also improved. Our findings suggest that N fertilizer recommendations for grain corn can be improved, however, further field validations are required. Author Keywords: corn, nitrogen, nitrogen mineralization, soil nitrogen supply, soil N test, southwestern Ontario
Soil Geochemistry and Normative Mineralogy across Canada
Soils play a crucial role in ecosystem functioning, for example, soil minerals provide important provisioning and regulate ecosystem services. This study used major soil oxides from the North American Soil Geochemical Landscapes Project (n=560) to assess elemental associations and infer soil minerals through exploratory data analysis and to determined quantitative soil mineralogy using a normative method, Analysis to Mineralogy (n=1170). Results showed elemental variability of oxides across the provinces of Canada and strong correlations occurred between elements indicative of soil mineral composition (e.g., Silicon and Aluminium). Principal component analysis inferred soil minerals from soil oxides trends on biplots and classified minerals, generally, as carbonates, silicates, and weathered secondary oxides. Spatial variability in minerals (quartz, plagioclase, potassium feldspar, chlorite, and muscovite) was related to the underlying bedrock geology. The use of Analysis to Mineralogy led to a reliable method of quantifying soil minerals at a large scale. Author Keywords: Analysis to Mineralogy, Exploratory data analysis, Normative procedures, North American Soil Geochemical Landscapes Project, Soil geochemistry, Soil mineralogy
Socio-Ecology and the Sacred
Within the complex socio-ecological systems of South and Southeast Asia, ancient sacred natural sites were created by, and imbued with, cultural and ideological values. These landscapes are liminal spaces or threshold environments between cultivated areas and wilder spaces; the practice of creating and maintaining them persists from ancient to modern times. This thesis examines sacred natural sites in three early state formations from 800 – 1400 CE: the Khmer (Cambodia), the Sinhalese (Sri Lanka) and the Chola (South India), why they persisted over time, and what significance they held. Several ancient sacred natural sites are active parts of societies today, and the ones chosen for this study span several categories: mountains, rivers, forests/groves, and caves. Using the paradigm of entanglement theory in a comparative context, this thesis analyzes sacred natural sites acting as key socio-ecological nodes enmeshed in complex dependent relationships within the landscapes of the South and Southeast Asia. Author Keywords: Comparative study, Entanglement theory, Sacred natural sites, Socio-ecological systems, South Asia, Tropical Societies
Social thermoregulation and potential for heterothermy
Northern and southern flying squirrels (Glaucomys sabrinus and G. volans, respectively) are experiencing a climate change induced increase in range overlap, resulting in recent hybridization. We investigated the occurrence of heterospecific communal nesting, a potential facilitator of hybridization, and aimed to confirm the presence of torpor, a potential barrier to hybridization, in flying squirrels. In wild-caught captive squirrels, we conducted a paired nest choice experiment and found that heterospecific nesting did occur, but in a lower frequency than conspecific nesting. Ambient temperature did not affect the frequency of grouped nesting. We attempted to induce torpor in flying squirrels in a laboratory through cold exposure while measuring metabolic rate and body temperature. Strong evidence of torpor was not observed, and metabolic rate remained unchanged with season. We conclude that torpor is not a barrier to hybridization in flying squirrels, but resistance to heterospecific nesting may indicate the existence of one. Author Keywords: heterospecific group, hybridization, northern flying squirrel, social thermoregulation, southern flying squirrel, torpor
Social discrimination by female polar bears (Ursus maritimus) when accompanied by dependent offspring during the ice-free season in southern and western Hudson Bay and James Bay
Polar bears are generally described as solitary, but features of their life cycles and habitats regularly necessitate interaction. Effective conspecific assessment, including accurate recognition and discrimination, likely confers benefits, especially to females accompanied by dependent young. Individuals in the Southern (SH) and Western (WH) Hudson Bay subpopulations are ideal for studying polar bear social behaviours because of the prolonged high densities of the ice-free season. First, I looked outside family groups to model their fine scale sociospatial organization on land. Capture locations were more likely to correspond to family groups when there were fewer neighbouring bears, when a greater proportion of neighbours were female, and when the focal individual and neighbours were significantly related. Second, I looked within the family group to assess offspring recognition. Of 288 offspring in 207 family groups captured in the SH subpopulation from 1999 through 2013, only one case of adoption (of a singleton) was observed. Author Keywords: Adoption, Kin Recognition, Logistic Regression, Maternity Analysis, Social Discrimination, Sociospatial

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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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