application/pdf

In the past few years there has been increasing attention paid to the influence of the motor system on numerical cognition. A 2010 study by Domahs, Moeller, Huber, Willmes and Nuerk tested German and Chinese university students. Number processing time was influenced by cross cultural differences in finger counting habits

This thesis replicated and elaborated on the aforementioned research design. This consisted of recruiting a sample of from a Chinese university and comparing them to a sample of Canadian university students. This study also compared within culture differences in participants' starting counting hand using additional SNARC analyses. A second experiment evaluated the possibility that asking participants about finger counting habits prior to the experiment may influence later answers. Cross cultural and within culture differences in finger counting habits influenced number processing. Participants also appeared to be more reliable reporters of their finger counting habits if asked at the end of the task rather than at the beginning.

Author Keywords: Canadian, Chinese, Cross-cultural, Finger-counting, Magnitude, Number

This dissertation traces the concept of transcendentalism from Kant's Critique of Pure Reason (1781) to Michel Foucault's historical a priori and Pierre Bourdieu's field and habitus, with implicit reference to Deleuze's `transcendental empiricism,' and the influence this trajectory has had on contemporary theory and culture. This general conceptual framework is used as the basis for a critical analysis of a series of examples taken from popular culture to highlight their transcendental conditions of possibility and the influence this conceptual paradigm has had on today's theory. The examples include the NFL `concussion crisis,' South Park's problematization of the discourse surrounding it, as well as the literature of Charles Bukowski, as an exemplification of an immanent writer-written situation. It is further suggested that, not only is transcendentalism an epistemological framework for thought, but it also doubles as an ontological principle for the emergence of a constitutively incomplete and unfinished reality.

Author Keywords: Bukowski, Concussion, Foucault, Kant, South Park, transcendental

The dissertation explores and defends the theory and practice of a Western-Islamic public sphere (which is secular but not secularist and which is Islamic but not Islamist), within which a critical Islamic intellectual universe can unfold, dealing hermeneutically with texts and politically with lived practices, and which, moreover, has to emerge from within the arc of two alternative, conflicting, yet equally dismissive suspicions defined by a view that critical Islam is the new imperial rhetoric of hegemonic orientalism and the opposite view that critical Islam is just fundamentalism camouflaged in liberal rhetoric. The Western-Islamic public sphere offers a third view, arising from ethical commitment to intellectual work, creativity, and imagination as a portal to the open horizons of history.

Author Keywords: Critical Islam, critique, history, Islamic reformation, public sphere, secular

Theoretical work on community recovery, development, stability, and resistance to species invasions has outpaced experimental field research. There is also a need for better integration between ecological theory and the practice of ecological restoration. This thesis investigates the dynamics of community assembly following peat mining and subsequent restoration efforts at Canada's most southerly raised bog. It examines mechanisms underlying plant community changes and tests predictions arising from the Dynamic Environmental Filter Model (DEFM) and the Fluctuating Resource Hypothesis (FRH). Abiotic, biotic and dispersal filters were modified to test a conceptual model of assembly for Wainfleet Bog. Hydrology was manipulated at the plot scale across multiple nutrient gradients, and at the whole bog scale using peat dams. Trends in time series of hydrological variables were related to restoration actions and uncontrolled variables including precipitation, evapotranspiration and arrival of beaver. Impacts of a changing hydrology on the developing plant community were compared with those from cutting the invasive Betula pendula. Transplanting experiments were used to examine species interactions within primary and secondary successional communities. Seedlings of B. pendula and the native Betula papyrifera were planted together across a peat volumetric water content (VWC) gradient. Impacts of beaver dams were greater than those of peat dams and their relative importance was greatest during periods of drought. Cutting of B.pendula had little effect on the secondary successional plant community developing parallel to blocked drains. Phosphorus was the main limiting nutrient with optimum levels varying substantially between species. Primary colonisers formed a highly stable, novel plant community. Stability was due to direct and indirect facilitative interactions between all species. Reduction in frost heaving was the major mechanism behind this facilitation. Interactions within the secondary successional community were mostly competitive, driven by light and space availability. However, restricted dispersal rather than competition limited further species recruitment. Predictions based on the DEFM were partially correct. A splitting of this model's biotic filter into competition and facilitation components is proposed. There was little support for the FRH based on nutrient levels and VWC. B. pendula had higher germination and growth rates, tolerance to a wider range of peat VWCs and a greater resistance to deer browsing than native birch. Peat mining, combined with restoration actions and the arrival of beaver has moved much of the bog back to an earlier successional stage circa 350+ years BP. Evidence points to B. pendula being a "back-seat driver" in the ecosystem recovery process. Indirect facilitation of a native by an exotic congener, mediated through herbivory, has not been described previously. Shifts in relative contributions of facilitation, competition and dispersal limitations to community assembly may be useful process-oriented measures for gauging progress in restoration.

Author Keywords: Betula pendula, community assembly, competition, facilitation, peatland, restoration

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

This study examines the foraging strategies of animal resource exploitation during the Middle Preclassic period (900-300 BC) at the ancient Maya site of Pacbitun, Belize. The faunal remains analyzed in this study were recovered from various domestic structures associated with the production of shell artifacts. Detailed taphonomic analyses have revealed that the Pacbitun faunal remains were particularly affected by weathering and density-mediated attrition. White-tailed deer was the prey most frequently acquired by the Middle Preclassic Maya of Pacbitun, followed by other lower-ranked artiodactyls. A variety of less profitable prey were sometimes included in the diet breadth. Using the central place forager prey choice model as a framework, the analysis of diet breadth, habitat use, and carcass transport patterns suggests that most animal resources were acquired from terrestrial habitats, at short distances from the site. Complete carcasses of large game appear to have been frequently transported to the site, where they were exploited for their meat and marrow. Comparisons with other Middle Preclassic faunal assemblages indicate significant differences in terms of taxonomic composition, with an emphasis on the procurement of fish and turtles. It is suggested that the Middle Preclassic Maya adopted foraging strategies focusing on the exploitation of local habitats, with occasional use of exotic resources.

Author Keywords: Animal, Belize, Foraging, Maya, Subsistence, Zooarchaeology

A wind tunnel study was conducted to investigate aeolian impact ripples in sand beds of varied texture from coarsely skewed to bimodal. Experimental data is lacking for aeolian megaripples, particularly in considering the influence of wind speed on ripple morphometrics. Additionally, the modelling community requires experimental data for model validation and calibration.

Eighteen combinations of wind speed and proportion of coarse mode particles by mass were analysed for both morphometrics and optical indices of spatial segregation. Wind tunnel conditions emulated those found at aeolian megaripple field sites, specifically a unimodal wind regime and particle transport mode segregation. Remote sensing style image classification was applied to investigate the spatial segregation of the two differently coloured size populations.

Ripple morphometrics show strong dependency on wind speed. Conversely, morphometric indices are inversely correlated to the proportion of the distribution that was comprised of coarse mode particles. Spatial segregation is highly correlated to wind speed in a positive manner and negatively correlated to the proportion of the distribution that was comprised of coarse mode particles. Results reveal that the degree of spatial segregation within an impact ripple bedform can be higher than previously reported in the literature.

Author Keywords: Aeolian, Impact Ripples, Megaripple, Self-organization, Wind Tunnel

Population density regulation is a fundamental principle in ecology, however there remain several unknowns regarding the functional expression of density dependence. One prominent view is that the patterns by which density dependence is expressed are largely fixed across a species, irrespective of environmental conditions. Our study investigated the expression of density dependence in Chlamydomonas reinhartti grown under a gradient of nutrient densities, and hypothesized that the relationship between per capita growth rate (pgr) and population density would vary from concave-up to concave-down as nutrients became less limiting. Contrary to prediction, we found that the relationship between a population's pgr and density became increasingly concave-up as nutrient levels increased. Our results suggest that density dependence is strongly variable depending on exogenous and endogenous processes acting on the population, implying that expression of density regulation depends extensively on local conditions. Population growth suppression may be attributable to environments with high intraspecific competition. Additional work should reveal the mechanisms influencing how the expression of density dependence varies across populations through space and time.

Author Keywords: Chlamydomonas reinhartti, density dependence, logistic model, population dynamics, single species growth, theta-logistic equation

Inducible defenses are plastic responses by an organism to the perception of predation risk. This dissertation focuses on three experiments designed to test the hypothesis that plastic ability is limited by energetic constraints. Chapter 1 provides a general introduction to phenotypic plasticity research and the theoretical costs and limitations affecting the expression of plastic traits. In Chapter 2, I tested the hypothesis that costs of early plasticity may be manifested by a reduced response to risk in later life stages. I found that amphibian embryos are able to detect and respond to larval predators, but that the energetic cost of those plastic responses are not equivalent among behavioural, growth, and morphological traits, and their expression differs between closely-related species. Chapter 3 explicitly examines the relationship between food resource availability and plasticity in response to perceived predation risk during larval development. Food-restricted tadpoles showed limited responses to predation risk; larvae at food saturation altered behaviour, development, and growth in response to predation risk. Responses to risk varied through time, suggesting ontogeny may affect the deployment of particular defensive traits. Chapter 4 examines the influence of maternal investment into propagule size on the magnitude of the plastic responses to predation risk in resulting offspring. I found that females in better body condition laid larger eggs and that these eggs, in turn, hatched into larvae that showed greater morphological plasticity in response to predation risk. Maternal investment can therefore affect the ability of offspring to mount morphological defenses to predation risk. Last, Chapter 5 provides a synthesis of my research findings, identifying specific factors constraining the plastic responses of prey to perceived predation risk. Overall, I found constraints on plastic responses imposed by the current environment experienced by the organism (resource availability), the prior experience of the organism (predator cues in the embryonic environment), and even the condition of the previous generation (maternal body condition and reproductive investment). Together, these findings both provide new knowledge and create novel research questions regarding constraints limiting phenotypic variation in natural populations.

Author Keywords: behaviour, inducible defense, Lithobates pipiens, morphometrics, phenotypic plasticity, predation risk

Monomethylmercury (MMHg), the most bioavailable form of mercury (Hg) and a potent neurotoxin, is present at elevated concentrations in Arctic marine mammals posing serious health threats to the local populations relying on marine food for their subsistence living. The sources of MMHg in the Arctic Ocean surface water and the role of dimethylmercury (DMHg) as a source of MMHg remain unclear. The objective of this research was to determine the sources and fate of methylated Hg species (MMHg and DMHg) in the marine ecosystem by investigating processes controlling the presence of methylated Hg species in the Arctic Ocean marine boundary layer (MBL) and surface waters. A method based on solid phase adsorption on Bond Elut ENV was developed and successfully used for unprecedented measurement of methylated Hg species in the MBL in Hudson Bay (HB) and the Canadian Arctic Archipelago (CAA). MMHg and DMHg concentrations averaged 2.9 ± 3.6 (mean ± SD) and 3.8 ± 3.1 pg m-3, respectively, and varied significantly among sampling sites. MMHg in the MBL is suspected to be the product of marine DMHg degradation in the atmosphere. MMHg summer (June to September) atmospheric wet deposition rates were estimated to be 188 ± 117.5 ng m-2 and 37 ± 21.7 ng m-2 for HB and CAA, respectively, sustaining MMHg concentrations available for bio-magnification in the pelagic food web. The production and loss of methylated Hg species in surface waters was assessed using enriched stable isotope tracers. MMHg production in surface water was observed from methylation of inorganic Hg (Hg(II)) and, for the first time, from DMHg demethylation with experimentally derived rate constants of 0.92 ± 0.82 x 10-3 d-1 and 0.04 ± 0.02 d-1 respectively. DMHg demethyation rate constant (0.98 ± 0.51 d-1) was higher than that of MMHg (0.35 ± 0.25 d-1). Furthermore, relationships with environmental parameters suggest that methylated Hg species transformations in surface water are mainly biologically driven. We propose that in addition to Hg(II) methylation, the main processes controlling MMHg production in the Arctic Ocean surface waters are DMHg demethylation and deposition of atmospheric MMHg. These results are valuable for a better understanding of the cycle of methylated Hg in the Arctic marine environment.

Author Keywords: Arctic Ocean, Atmosphere, Demethylation, Dimethylmercury, Methylation, Monomethylmercury