Graduate Theses & Dissertations

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Understanding the establishment of Typha spp. in North America using population genetics and common garden studies
There are three cattail (Typha) taxa in Canada: T. latifolia (native), T. angustifolia (introduced), and their hybrid T. x glauca. The latter is invasive in regions around the Laurentian Great Lakes, and I investigated the potential role that commercial suppliers may be playing in the introduction of non-native Typha by comparing genotypes of North American, European, and commercially available plants. I found that Ontario garden centres are importing both hybrids and non-native lineages of T. angustifolia into Canada, but was unable to identify the provenance of T. latifolia. I also investigated the possibility that the hybrid cattail leaf litter shade and leachate influences germination and early growth of the parental species of the hybrids. Using three common garden experiments, I found that T. x glauca leaf litter suppresses germination rates of the three taxa. In the early seedling growth experiment, plant performance varied by taxa, and for the competition experiment there were no intra- or interspecific competition or treatment effects on the performance of plants. Overall, my research identified a potential mechanism allowing T. x glauca to dominate wetlands, and also shows that non-native lineages are being introduced into Canada through commercial trade Author Keywords: Competition, Germination, Non-native lineages, Plant nurseries, Seedling Growth, Typha spp.
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
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
Time-dependent effects of predation risk on stressor reactivity and growth in developing larval anurans (Lithobates pipiens)
The predator vs. prey dynamic is an omnipresent factor in ecological systems that may drive changes in life history patterns in prey animals through behavioural, morphological, and physiological changes. Predation risk can have profound effects on the life history events of an animal, and is influenced by the neuroendocrine stress response. Activation of the hypothalamic-pituitary-adrenal/interrenal axis, and the induction of stress hormones (e.g., corticosterone (CORT)) have been shown to mediate the onset of inducible anti-predator defensive traits including increased tail-depth, and reduced activity. The predator-prey relationship between dragonfly nymphs and tadpoles can be a powerful model system for understanding mechanisms that facilitate changes in the stress response in accordance with altered severity of risk. It has been well demonstrated early in tadpole ontogeny that increased corticosterone (CORT) levels, observed within three weeks of predator exposure, are correlated with increased tail depth morphology. However, the reactivity of the stress response in relation to the growth modulation in developing prey has yet to be fully explored. Accordingly, this thesis assessed the stress and growth response processes in tadpoles that were continuously exposed to perceived predation risk later in ontogeny. Continuous exposure of prey to predation risk for three weeks significantly increased CORT levels, and tail depth. However, tadpoles exposed to six weeks of predation risk acclimated to the presence of the predator, which was observed as a significant reduction of stressor-induced CORT levels. In addition, although increased tail depth has been attributed to predator defense, predator-naïve tadpoles began to display similar tail depth morphology as treated tadpoles at the six week time point. Thus, this thesis suggests that the stress response in lower vertebrate systems (e.g., tadpoles) may operate in a similarly complex manner to that observed in higher vertebrates (e.g., rats), for which severity of risk associated with the stressor aids in defining activity of the stress response. Moreover, the lack of morphological difference between treatments among tadpoles exposed later in ontogeny suggests that the mechanisms for inducing defenses are normal morphological traits in the development of the animal. This thesis paves the way for future research to elucidate the relationship between the neuroendocrine stress response and hormonal pathways involved in growth modulation in the presence of environmental pressures. Author Keywords: Acclimation, Corticosterone, Growth Modulation, Predation Risk, R. pipiens, Tadpole
Executive Function as a Predictor of Emotional, Behavioural, and Social Competence Problems in Children with Epilepsy
The study aimed to examine the association between different components of executive function (EF) and emotional, behavioural, and social competence problems (EBSP) in children with epilepsy. Although there is evidence of an association between EBSP and EF in typically developing children, little research has examined this relation in children with epilepsy. The sample comprised of 42 children with epilepsy, aged 6.0 to 18.1 years old. Results showed that EBSP were associated with EF in these children; however, different components of EF were related to different EBSP. Shifting was a significant predictor of emotional, behavioural, and social competence problems in children with epilepsy, whereas inhibition was a significant predictor of behavioural problems. This suggests that children with epilepsy, with different EF profiles may be at-risk for developing different types of problems. These results may aid researchers and clinicians with the development of new techniques to identify and treat children with EBSP. Author Keywords: behavioural problems, emotional problems, epilepsy, executive function, social competence
Elemental Variation in Daphnia
Environmental variation can affect consumer trait expression and alter ecological and evolutionary dynamics in natural populations. However, although dietary nutrient content can vary by an order of magnitude in natural ecosystems, intra-specific differences in consumer responses to food quality have not been thoroughly investigated. Therefore, the purpose of my dissertation was to examine the influence of dietary nutrition and other environmental factors on consumer phenotypic variation using the freshwater cladoceran Daphnia. I conducted a series of complementary laboratory and field studies where I examined the effects of dietary phosphorus (P) content and additional biological/environmental variables (multi-elemental limitation, genetic variation, and temperature) on daphnid life-history, biochemistry, body elemental composition, and population growth. In general, phenotypic expression within a species varied significantly in response to all experimental variables, but the relative influence of each was highly context dependent. In my first chapter, I found that dietary P content and environmental calcium (Ca) concentrations both altered Daphnia body Ca:P ratios and growth rates of individuals and affected intrinsic rates of increase at the population level. However, food quality appeared to have a much larger effect on trait expression, and body Ca:P ratios were highly sensitive to other forms of dietary nutrient limitation. Next, I documented significant quantitative genetic variation and phenotypic plasticity in daphnid P content, growth, and P use efficiency of field collected animals grown across dietary P gradients. Trait expression was also influenced by genotype X diet interactions suggesting that consumer responses to dietary nutrient limitation can be heritable and may be adaptive in different nutrient environments. Finally, I found that temperature appeared to override food quality effects and decouple P metabolism in natural Daphnia populations, but total biomass production was affected by both dietary P content and temperature, depending on the nutrient content of the lake. Overall, my dissertation shows that consumer responses to nutrient limitation can vary significantly within a species and that changes in trait expression may be modified by other environmental variables. These results should be incorporated into existing stoichiometric models and used to investigate the eco-evolutionary consequences of consumer phenotypic variation in response to nutritional stress. Author Keywords: ecological stoichiometry, evolution, life-history, nutrient limitation, nutrient metabolism, zooplankton
Mutation of the B10 Tyrosine and E11 Leucine in Giardia intestinalis Flavohemoglobin
The flavohemoglobin in Giardia intestinalis (gFlHb) is the only known protozoan member of a protein class typically associated with detoxifying nitric oxide (by oxidation to nitrate) in bacteria and yeast. Mutants of the B10 tyrosine (Y30F) and E11 leucine (L58A), conserved residues thought to influence ligand binding, were expressed and studied using Resonance Raman (RR) spectroscopy. In the wild type protein, RR conducted using a carbon monoxide probe detects two distinct Fe-CO stretches associated with two different active site configurations. In the open configuration, CO does not interact with any polar side chains, while in the closed configuration, CO strongly interacts with one or more distal residues. Analysis of the Y30F mutant provided direct evidence of this tyrosine’s role in ligand stabilization, as it had only a single Fe-CO stretching mode. This stretching mode was higher in energy than the open conformer of the wild type, indicating a residual hydrogen bonding interaction, likely provided by the E7 glutamine (Q54). In contrast the L58A mutant had no effect on the configurational nature of the enzyme. This was unexpected, as the side chain of L58 sits atop the heme and is thought to regulate the access of distal residues to the heme-bound ligand. The similar spectroscopic properties of wild type and L58A suggest that any such regulation would involve rapid conformational dynamics within the heme pocket. Author Keywords: B10 Tyrosine, Catalytic Globin, E11 Leucine, Flavohemoglobin, gFlHb, Giardia intestinalis
An Evaluation of Wastewater Treatment by Ozonation for Reductions in Micropollutant Toxicity to Fish
Micropollutants are discharged into the aquatic environment with industrial and domestic wastewater and these compounds may cause toxic effects in aquatic organisms. In this study, the toxic effects to fish of micropollutants extracted from ozonated and nonozonated municipal wastewater effluent (MWWE) were measured in order to assess the effectiveness of ozonation in reducing toxicity. Juvenile rainbow trout (Oncorhynchus mykiss) injected with extracts prepared from ozonated MWWE had significantly reduced induction of plasma vitellogenin (VTG), significantly reduced hepatic total glutathione (tGSH) levels and an elevated oxidized-to-total glutathione (GSSG-to-tGSH) ratio. Exposure of Japanese medaka (Oryzias latipes) embryos to extracts prepared from both ozonated and non-ozonated MWWE resulted in elevated developmental toxicity in both treatment groups. These results indicate that wastewater treatment by ozonation reduces the estrogenicity of wastewater, but treatment may induce oxidative stress and embryonic developmental toxicity due to the production of toxic by-products. Author Keywords: Estrogenicity, Micropollutants, Oxidative stress, Ozonation, Toxic by-products, Wastewater
Impact of Wetland Disturbance on Phosphorus Loadings to Lakes
Total phosphorus (TP) concentrations have declined in many lakes and streams across south- central Ontario, Canada over the past three decades and changes have been most pronounced in wetland-dominated catchments. In this study, long-term (1980-2007) patterns in TP concentrations in streams were assessed at four wetland-dominated catchments that drain into Dickie Lake (DE) in south-central Ontario. Two of the sub-catchments (DE5 and DE6) have particularly large wetland components (31-34 % of catchment area), and wetlands are characterised by numerous standing dead trees and many young live trees (18 – 27 year old). These two streams exhibited large peaks in TP and potassium (K) export in the early 1980s. In contrast, TP and K export from DE8 and DE10 (wetland cover 19 – 20 %) were relatively flat over the entire record (1980-2007), and field surveys indicated negligible standing dead biomass in these wetlands, and a relatively healthy, mixed-age tree community. Furthermore, K:TP ratios in the DE5 and DE6 streams were around 5 in the early 1980s; very similar to the K:P ratio found in biomass, and as stream TP levels fell through the 1980s, K:TP ratios in DE5 and DE6 stream water increased. The coincidence of high TP and K concentrations in the DE5 and DE6 streams as well as evidence of a disturbance event in their wetlands during the early 1980s suggest that the two are related. The diameter of standing dead trees and allometric equations were used to estimate the amount of TP that would have been held in readily decomposed tree tissues in the DE5 wetland. The amount of P that would have been held in the bark, twig, root and foliage compartments of just the standing dead trees at DE5 was approximately half of the amount of excess stream TP export that occurred in the 1980s. This work suggests that disturbance events that lead to wetland tree mortality may contribute to patterns in surface water TP observed in this region. Author Keywords: Chemistry, Disurbance, Nutrients, Tree Death, Water, Wetland
Testing for Interspecific Hybridization and a Latitudinal Cline Within the Clock Gene Per1 of the Deer Mouse (Peromyscus maniculatus) and the White-Footed Mouse (Peromyscus leucopus)
The recent northward expansion of the white-footed mouse (Peromyscus leucopus) in response to climatic changes provides a natural experiment to explore potential adaptive genetic variation within the clock gene Per1 in Peromyscus undergoing latitudinal shifts, as well as, the possibility of hybridization and introgression related to novel secondary contact with its sister species the deer mouse (Peromyscus maniculatus). Because clock genes influence the timing of behaviors critical for survival, variations in genotype may reflect an organism’s ability to persist in different environments. Hybridization followed by introgression may increase the adaptive potential of a species by quickly generating adaptive variation through novel genetic recombination or by the transfer of species-specific alleles that have evolved in response to certain environments. In chapter 2, I used microsatellite and mtDNA markers to test for hybridization and introgression between P. maniculatus and P. leucopus and found that interbreeding is occurring at a low frequency (<1%). In chapter 3, I tested for a latitudinal cline in a polyglycine repeat located within the Per1 gene of Peromyscus and discovered a putative cline in the Per1-142 and Per1-157 allele of P. leucopus and P. maniculatus, respectively. Chapter 4, further expands upon these findings, limitations, and the lack of evidence supporting introgression at the Per1 locus. Despite this lack of evidence, it is possible that novel hybridization has or could lead to adaptive introgression of other genes, allowing for the exchange of adaptive alleles or traits that could be advantageous for range expansion and adaption to future environmental changes. Author Keywords: Clock genes, Hybridization, Latitudinal gradient, Per1, Peromyscus, Range Expansion
An Assessment of Spatial Trends in the Accumulation of Oil Sands Related Metals in the Clearwater River Valley and Temporal Trends in Six Northern Saskatchewan Lakes
The objective of this thesis was to assess current spatial trends and historic trends in the accumulation of trace metals related to the Athabasca Oil Sands Region (AOSR). The AOSR hosts some of the largest industrial developments in Canada, yet relatively little is known about the transport and fate of trace metal emissions from the region – particularly in the relatively remote areas to the east of the AOSR. Lichens are widely used as biomonitors and are employed in this thesis to assess the range of metals deposition within the Clearwater River and Athabasca River Valleys. Lake sediment cores can retain a historical record of the long-range transport and deposition of metals but can also respond to large regional metal emissions sources. This thesis used lake sediment cores to assess temporal trends in metals accumulation in six road accessible lakes in NW Saskatchewan that are likely to be used by local residents. Results show that metal concentrations (V, Co, Cu, Ni, Pb, Zn, Zr and Cd ) in lichen decline exponentially with distance from the AOSR and approach background levels within a few kilometers . Results from lake sediment cores show that there was no evidence that metal concentrations had increased due to industrial activities in the AOSR. Author Keywords: Air Emissions, Lakes, Lichens, Oil Sands, Saskatchewan, Trace Metals
Regional differences in the whistles of Australasian humpback dolphins (genus Sousa)
Most delphinids produce narrowband frequency-modulated whistles with a high level of plasticity to communicate with conspecifics. It is important to understand geographic variation in whistles as signal variation in other taxa has provided insight into the dispersal capabilities, genetic divergence and isolation among groups, and adaptation to ecological conditions. I investigated whistle variation of Indo-Pacific humpback dolphins (Sousa chinensis chinensis), Taiwanese humpback dolphins (S. c. taiwanensis) and Australian humpback dolphins (S. sahulensis) to test whether differences in whistles support the hypotheses of population structure, regional and species differences in the genus Sousa, which were based on morphological and genetic data. I also investigated important factors that may contribute to local distinctiveness in whistles including behavioural state, group size, and the influence of vessel noise. Multivariate analyses of seven acoustic variables supported the hypotheses of population structure, regional and species differences. Acoustic diversification between groups is likely influenced by behaviour and social contexts of whistles, and environmental noise. The use of sound to identify discrete groups of humpback dolphins may be important in future studies where genetic and morphological studies may not reveal recent differentiation or are difficult to conduct. Author Keywords: Bioacoustics, Cetacean, Geographic variation, Population biology, Sousa, Whistle characteristics

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