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Graduate Theses & Dissertations
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- origin and ecological function of an ion inducing anti-predator behaviour in Lithobates tadpoles
- Chemical cues are used commonly by prey to identify predation risk in aquatic environments. Previous work has indicated that negatively-charged ions of m/z 501 are possibly a kairomone that induces anti-predator responses in tadpoles. This thesis found that this ion species: (i) is produced by injured tadpoles; (ii) exhibits increased spectral intensity with higher tadpole biomass; and (iii) is not produced by starved predators. These results refute the hypothesis that the ion is a kairomone, and rather support its role as an alarm cue released from tadpoles. High resolution mass spectrometry (HR-MS) revealed a unique elemental composition for [M-H]-, m/z 501.2886, of C26H45O7S-. Collision induced dissociation (CID) of ion m/z 501 formed product ions of m/z 97 and m/z 80, HSO4- and SO3-, respectively, indicating the presence of sulfate. Green frog (Lithobates clamitans) tadpoles exposed to m/z 501, and an industrial analogue, sodium dodecyl sulphate (NaC12H25O4S), exhibited similar anti-predator responses, thereby suggesting the potential role of organic sulfate as a tadpole behavioural alterant. Author Keywords: Alarm cue, Amphibian, Chemical Ecology, Mass spectrometry, Predator-prey interactions
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- Utilizing Class-Specific Thresholds Discovered by Outlier Detection
- We investigated if the performance of selected supervised machine-learning techniques could be improved by combining univariate outlier-detection techniques and machine-learning methods. We developed a framework to discover class-specific thresholds in class probability estimates using univariate outlier detection and proposed two novel techniques to utilize these class-specific thresholds. These proposed techniques were applied to various data sets and the results were evaluated. Our experimental results suggest that some of our techniques may improve recall in the base learner. Additional results suggest that one technique may produce higher accuracy and precision than AdaBoost.M1, while another may produce higher recall. Finally, our results suggest that we can achieve higher accuracy, precision, or recall when AdaBoost.M1 fails to produce higher metric values than the base learner. Author Keywords: AdaBoost, Boosting, Classification, Class-Specific Thresholds, Machine Learning, Outliers
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- Comparative phylogeography in conservation biology
- Phylogeographic histories of taxa around the Great Lakes region in North America are relevant to a range of ongoing issues including conservation management and biological invasions. In this thesis I investigated the comparative phylogeographic histories of plant species with disjunct distributions and plant species with continuous distributions around the Great Lakes region; this is a very dynamic geographic area with relatively recent colonisation histories that have been influenced by a range of factors including postglacial landscape modifications, and more recently, human-mediated dispersion. I first characterized four species that have disjunct populations in the Great Lakes region: (Bartonia paniculata subsp. paniculata, Empetrum nigrum, Sporobolus heterolepis, and Carex richardsonii). Through comparisons of core and disjunct populations, I found that a range of historical processes have resulted in two broad scenarios: in the first scenario, genetically distinct disjunct and core populations diverged prior to the last glacial cycle, and in the second scenario more recent vicariant events have resulted in genetically similar core and disjunct populations. The former scenario has important implications for conservation management. I then characterized the Typha species complex (T. latifolia, T. angustifolia, T. x glauca), which collectively represent species with continuous distributions. Recent microevolutionary processes, including hybridization, introgression, and intercontinental dispersal, obscure the phylogeographic patterns and complicate the evolutionary history of Typha spp. around the Great Lakes region, and have resulted in the growing dominance of non-native lineages. A broader geographical comparison of Typha spp. lineages from around the world identified repeated cryptic dispersal and long-distant movement as important phylogeographic influences. This research has demonstrated that comparisons of regional and global evolutionary histories can provide insight into historical and contemporary processes useful for management decisions in conservation biology and invasive species. Author Keywords: chloroplast DNA, conservation genetics, disjunct populations, invasive species, phylogeography, postglacial recolonisation
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- Expression and characterization of cytochrome b5 from Giardia lamblia
- Giardia lamblia is an intestinal parasite found globally in freshwater systems that is responsible for endemic outbreaks of infectious diarrhea. As a unicellular parasite that lacks mitochondria, a respiratory chain and lives in the anaerobic environment of its host's intestine, Giardia was assumed for decades to lack heme proteins. However, its genome encodes several putative heme proteins, including three with sequence similarity to the cytochrome b5 family, referred to as Giardia cytochromes b5 (gCYTb5). Recombinant expression of one of these genes (gCYTb5-I), results in a protein (17-kDa) that is isolated with noncovalently bound heme. Resonance Raman and UV-visible spectra of gCYTb5-I in oxidized and reduced states resemble those of microsomal cytochrome b5, while sequence alignment and homology modelling supports a structure in which a pair of invariant histidine residues act as axial ligands to the heme iron. The reduction potential of gCYTb5-I measured by cyclic voltammetry is -165 mV vs the standard hydrogen electrode and is relatively low compared to those of other family members. The amino- and carboxy-terminal sequences that flank the central heme-binding core of the gCYTb5 are highly charged and do not occur in other family members. An 11-kDa core gCYTb5-I variant lacking these flanking sequences was also able to bind heme; however, we observe very poor expression of this truncated protein as compared to the full-length protein. Author Keywords: b-type cytochrome, cytochrome b5, electron transfer protein, Giardia intestinalis, heme/heam protein, spectroelectrochemistry
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- Reassessing Bioarchaeological Sex Determination and Research into Gender at the Early Anglo-Saxon Worthy Park Burial Ground Round in Hampshire, England
- When bioarchaeologists investigate ancient gender identity, they typically place skeletal remains into one of six sex assessment categories: male, female, possible/probable male, possible/probable female, ambiguous, and indeterminate. However, the study samples are often reduced to male and female reproducing a male/female gender and sex binary prevalent in the "Western" cultural milieu and bioarchaeology when inferences are made about gender and sex in the past. In order to allow for the existence of non-binary cultural genders and biological sexes, this thesis: 1) demonstrates the multitude of ethnographic, ethnohistoric, historic, and medical evidence relating to non-binary sex and gender expression; 2) tests a method inspired by Whelan (1991) that looks at gender as an identity not fully inspired by biological sex; 3) keeps all sex assessment categories used by bioarchaeologists separate in analysis and interpretation; and 4) analyses patterns relating to all available material culture and biological attributes in a mortuary sample to investigate gender identity. This thesis used the Early Anglo-Saxon (470-600 AD) burial ground at Worthy Park in Hampshire to achieve these objectives. This thesis found that when examining all sex assessment categories among all mortuary variables, only the male sex was clearly defined by its mortuary assemblage. This suggests a one gender structure corresponding to linguistic evidence for one gender in Old English. Author Keywords: Anglo-Saxon, Bioarchaeology, Gender identity, Mortuary archaeology, Osteoarchaeology, Sex determination
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- Detecting anti-estrogens and anti-androgens in surface waters impacted by municipal wastewater discharges and agricultural runoff
- This study focused on detecting 22 target anti-estrogenic and anti-androgenic compounds in surface waters influenced by both discharges of municipal wastewater and agricultural runoff in Canada and Argentina. Polar organic chemical integrative samplers (POCIS) were used to monitor the target compounds in surface waters. The removals of the target compounds in a municipal wastewater treatment plant (WWTP) in Canada were also evaluated. In both Canada and Argentina pesticides with potential anti-estrogenic and anti-androgenic activities were detected in the surface waters. The highest concentrations were found in Argentina (up to 1010 ng L-1) in areas impacted by heavy agricultural practices. Cyproterone acetate and bicalutamide were the only two anti-cancer drugs detected only at the Canadian study site, the Speed River, ON. In the Guelph WWTP, that discharges into the Speed River, these target compounds were not all efficiently removed (>70%) during treatment. Overall, this study provides insight to possible anti-estrogenic and anti-androgenic compounds that may be contributing to endocrine disrupting activities in surface waters. Author Keywords: Anti-androgens, Anti-estrogens, Cancer Therapy Drugs, Current use pesticides, Pharmaceuticals and Personal Care Products, Polar Organic Chemical Integrative Samplers
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- Sexual Dimporphism and Population Dynamics of Sub-Arctic Breding Dunlin (Calidris alpina hudsonia) near Churchill, Manitoba, Canada
- Around the world, many populations of migratory shorebirds appear to be declining. Conservation strategies to reverse declining trends rely on, among other information, a firm understanding of breeding ground population dynamics. From 2010 to 2014, I studied a breeding population of Dunlin (Calidris alpina hudsonia) near Churchill, Manitoba using mark-recapture methods. I found that females were significantly larger than males. I subsequently developed an equation based on morphological features that successfully classified 87.1% of females and 92.6% of males, sexed using molecular techniques. Using program MARK, I quantified the annual apparent survival of adults (± SE) within the breeding population (0.82 ± 0.063 for males, 0.73 ± 0.12 for females). Transient adults made up a significant percentage of the female population (32%, P = 0.011), but non-significant in the male population (12%, P > 0.05). Re-sight rate was high for both sexes, and ranged from 0.86-0.90 per year. Sex, year, and nest initiation date were the factors that had the greatest influence on annual returns. There was no significant difference in mean inter-annual nest site distance between sexes (male: 82.01 ± 13.42 m, female: 208.38 ± 55.88 m, P > 0.05). The high survival estimates obtained in this study suggest that the breeding population is stable and may not be contributing to suspected population declines within the subspecies. Author Keywords: demography, discriminant function analysis, mark-recapture, sexual size dimorphism, survival
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- From Negation to Affirmation
- Forensic scientific practice is conventionally understood as a solution to absence. With every technological advance the power and span of the archive grows and with it revives hopes of uncovering facts and locate bodies that might put genocide denial and/or negationism to rest. Destruction, however, continues to define the reality and conditions for testimony in the aftermath of mass atrocity. This means that even as forensic scientific practice grows in its capacity to presence that which was previously unpresentable, destruction and the concomitant destruction of archive require that we consider what it means to remember with and without the archive alike. This dissertation explores the impact of forensic science on cultural memory through a choice of two case studies (set in Kosovo and Srebrenica respectively) where forensic scientific methods were involved in the investigation of atrocities that were openly denied. This dissertation makes an agnostic argument that the biblical example of the empty tomb can serve as a paradigm to understand the terms of witnessing and testifying to absence in the era of forensic scientific investigations. Specifically, it posits the following theses with regards to the empty tomb: it is a structure and an event that emerges at the intersection of forensic science’s dual property as an indexical technique and as a witness function, it cannot be validated through historiographic or forensic scientific methods (it is un-decidable) and as such serves as a corrective the fantasy of the total archive, is represented in the contemporary genre of forensic landscape; and because it breaks with the forensic imperative, it compels alternative uses for testimony and memorial practices that need not be defined by melancholia as it can accommodate forms of testimony that are joyous and life affirming. Author Keywords: Absence, Archive, Forensic, Memory, Testimony, Witness
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- Mythopoeia Sylvatica
- Since British colonization of North America and the beginning of Anglo-speaking Euro-Canada and the United States, myth-making or representations of the forests have witnessed degradation and loss of old-growth forest ecosystems or intact sylvan landscapes. Canadian and American versions of the story of the North American Forests shared the same trajectory: forests as ‘wasted-land’ or the sylvan wilderness (terra nullius) divided into properties and cleared to “improve” the land for settlement/agriculture, forests as storehouses for timber and imperial expansion, forest landscapes and specific forest trees as identity politics and sources of industrial and economic power. While forests are recognized according to various stakeholders’ values today, what is commonly accepted as a forest varies widely. The meaning given to “forest” determines related terms and concepts, such as “sustainable forestry” and “reforestation.” This thesis addresses the issue of social-bioecological degradation, loss, and dis(re)membering of old-growth forests and problematizes traditional Western relationships with old wildwoods shaped by notions of space, politics, and economy. In the forest topos, the core question becomes which forest(s) are being imagined, represented, and remembered? Whose environmental imagination is shaping the landscape? As a critical topographical exploration of the North American forests through six witness trees, this thesis demonstrates how the meanings imbued in trees and wild woods come to determine the fate of the forests. It reveals how colonial values and trends persist in our societies still, and calls for an ethical social-ecological reimagining of the forests through traditions of ethical storytelling and environmental witnessing. Author Keywords: critical topography, environmental generational amnesia, environmental witnessing, forests, social-ecological systems, witness trees
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- the sex killer drives a panel pin into his ear-hole
- I have two goals. One, to offer new insights into Vienna Actionism (VA) and their notorious performances, through Gilles Deleuze and Félix Guattari’s notion of the body without organs (BwO); and two, not simply to provide descriptions of the Vienna Actionists’ performances, but also to write what I am calling a thesis without organs. Documents from the Vienna Actionists, specifically Muehl’s Leda and the Swan (1964), Brus’ Vienna Walk (1965) and Nitsch’s O.M. Theatre (1960-present), become documents without organs; they are documents that do not simply document original performances, but re-perform original performances while acting as performances themselves. Challenging the notion of live performance as fundamentally separate from its documentation (as performance theorist Peggy Phelan argues) through what Philip Auslander calls the document’s performativity and what Christopher Bedford calls a viral ontology of performance, my thesis becomes a performance in and of itself. A thesis without organs. Keywords: performance, performativity, viral ontology of performance, body without organs, rhizome, dirt, metaphor, metonymy, Vienna Actionism, Gilles Deleuze, Félix Guattari, Peggy Phelan, Philip Auslander, Christopher Bedford, Mary Douglas. Author Keywords: Body without Organs, Performance, Performativity, Vienna Actionism
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- Politics of Memory
- In dialogue with the critical scholarship on war and remembrance, my research deals with the construction, contestation and negotiation of collective memory in contemporary Vietnam with a focus on commemorations devoted to dead soldiers. Utilizing the methodologies of cultural studies and ethnography, this research seeks to comprehend the politics of memory which characterize collective memory as a social phenomenon whose meanings, interpretations and forms are variedly constructed from a certain social group to the next. Empirically, in this research, constitutive elements of Vietnamese postwar memoryscapes including the hero-centered discourse sanctioned by the Communist Party and the Socialist state, the family remembrance rooted in religious and kinship mandates and the newly emerged online ecology of memory are examined in their own nature as well as in their complicated intertwinements and constant interactions with each other. Case studies and specific methods of individual interview, participant observation and cultural analysis enable the author to approach and identify a wide range of forms and intersections between official and vernacular practices, between oral and living history and institutionalized and cultural presentations of memory. While considering these issues specifically in the Vietnamese context, my dissertation contributes to the increasing theoretical debates in the field of memory studies by exploring the relation of power and the symbolic struggle within and between different social agents involved. As it emphasizes the dynamic and power of memory, this research furthermore situates the phenomenon of collective memory in its dialogues with a broader cultural political environment of postwar society, which is characterized as a hybrid condition embracing processes of nationalism, modernization and post-socialist transformation. Significantly, during these dialogues, as demonstrated in this research, memory works embrace presentism and future-oriented functions which require any social group who is involved to negotiate and renegotiate its position, and to structure and restructure its power. Last but not least it must construct and reconstruct its own versions of the past. Author Keywords: collective memory, Dead soldiers, postwar society, Socialist Vietnam, the politics of memory, war remembrance
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- Impact of Invasive Earthworms on Soil Respiration and Soil Carbon within Temperate Hardwood Forests
- Improving current understanding of the factors that control soil carbon (C) dynamics in forest ecosystems remains an important topic of research as it plays an integral role in the fertility of forest soils and the global carbon cycle. Invasive earthworms have the potential to alter soil C dynamics, though mechanisms and effects remain poorly understood. To investigate potential effects of invasive earthworms on forest C the forest floor, mineral soil, fine root biomass, litterfall and litter decomposition rates and total soil respiration (TSR) over a full year were measured at two invaded and one uninvaded deciduous forest sites in southern Ontario. The uninvaded site was approximately 300m from one of the invaded sites and a distinct invasion front between the sites was present. Along the invasion front, the biomass of the forest floor was negatively correlated with earthworm abundance and biomass. There was no significant difference between litterfall, litter decomposition and TSR between the invaded and uninvaded sites, but fine root biomass was approximately 30% lower at the invaded site. There was no significant difference in soil C pools between the invaded and uninvaded sites. Despite profound impacts on forest floor soil C pools, earthworm invasion does not significantly increase TSR, most likely because increased heterotrophic respiration associated with earthworms is largely offset by a decrease in autotrophic respiration caused by lower fine root biomass. Author Keywords: Biological Invasions, Carbon, Earthworms, Forest Ecosystems, Forest Floor, Soil Respiration