Graduate Theses & Dissertations

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Genetic Networks to Investigate Structure and Connectivity of Caribou at Multiple Spatial and Temporal Scales
Understanding genetic structure, connectivity, and movement of a species iscritical to management and conservation. Genetic network approaches allow the analysis of genetic information with flexibility and few prior assumptions. In chapter one, I tested the ability of individual-based genetic networks to detect fine-scale structure and connectivity in relation to sampling efforts. My findings revealed individual-based genetic networks can detect fine-scale genetic structure of caribou when using 15 highly variable microsatellite loci. Sampling levels less than 50% of the estimated population size resulted in highly disconnected networks which did not allow for accurate structure analysis; however community detection algorithms were robust in grouping closely related individuals despite low sampling. In chapter two, I used individual-based and population-based genetic networks to investigate structure, connectivity, and movement of caribou across a large study area in Western Canada. A community detection algorithm partitioned the population-based genetic network at multiple spatial scales which uncovered patterns of hierarchical genetic structure and highlighted patterns of gene flow. The hierarchical population structure results aligned with the known distribution of different caribou Designatable Units (DUs) and additional structure was found within each DU. Furthermore, individual-based networks that were constructed with a subset of samples from the Mackenzie Mountains region of the Northwest Territories revealed patterns of long-distance movement and high connectivity across the region. Author Keywords: Biological Conservation, Caribou, Community Detection, Connectivity, Genetic Networks, Structure
Indirect Effects of Hyperabundant Geese on Sympatric-Nesting Shorebirds
Rising populations of Lesser Snow and Ross’ geese (hereafter collectively referred to as light geese) breeding in the North American Arctic have caused significant environmental change that may be affecting some populations of nesting shorebirds, which in contrast to geese, have declined dramatically. In this thesis I examine the indirect effects of light geese on sympatric-nesting shorebirds. I first conduct a literature review of the effects of light geese on northern wildlife and outline multiple mechanisms in which geese may affect shorebirds in particular. Using bird survey data collected in plots situated across the Canadian Arctic from 1999 to 2016, I then identify spatial effects of light goose colonies on shorebird, passerine, and generalist predator densities. The densities of cover- nesting shorebirds and passerines were depressed near goose colonies while the densities of open-nesting shorebirds were less so. Next, using habitat data collected at random sites and shorebird nest sites situated at increasing distances from a goose colony on Southampton Island, Nunavut, I outline the effects of geese on shorebird nest site selection. I found that the availability of sedge meadow and amount of lateral concealment increased as a function of distance from goose colony; cover-nesting shorebirds selecting nest sites with less concealment and sedge meadow near the colony. Then, to characterize spatial effects of light geese on predators and risk of predation I used time-lapse cameras and artificial shorebird nests placed at increasing distances from the goose colony. Activity indices of gulls, jaegers, and foxes were all negatively correlated with distance from the goose colony while the reverse was true for artificial nest survival probability. Finally, I relate changes in ground cover to goose use and link these changes to variation in invertebrate communities. I then use DNA metabarcoding to characterize the diet of six shorebird species across study sites and identify inter-site variation in the biomass of dominant shorebird prey items. Prey item biomass was elevated at the two study sites near the goose colony potentially indicating an enhancing effect of goose fecal deposition. Overall, I show that light geese interact with shorebirds in multiple ways and negatively affect their habitat availability, nest site selection, and risk of predation, effects that likely outweigh the positive effects of enhanced prey availability. Author Keywords:
Biogeography of Carabidae (Coleoptera) in the Boreal forest
Basic biogeographic information is lacking for many species, such as where species are found, and how they dispersed there. Using ground beetles collected during 2008-2015 from across northern Ontario and Akimiski Island, Nunavut, I present new information on ground beetle distribution in this eastern Nearctic boreal forest, including 2 first Canadian records, 9 first provincial and 48 first territorial records, as well as 74 new records that extend the known range of many large and common ground beetles several hundred kilometres. I used these distributions to redress the knowledge gap that includes fundamental distribution data, i.e. the Wallacean shortfall, and to inform later chapters in my thesis.In Chapter 3, I examine the range expansion pattern of Carabus granulatus, a non-native species, as it spread across northeastern North America and I provide a new range record. Northern Ontario is already under threat from non-native species entering the region and it is important to conduct studies in the region before more disturbance associated with development occurs. In Chapter 4, I examine the hypothesis that northern Ontario effectively acts as a climate plateau for poikilotherms, using the predictions from Bergmann's rule as my metric. The body length of ground beetles does not appear to change over the small temperature gradient that exists across northern Ontario latitudes, supporting the climate plateau hypothesis. In Chapter 5, I test hypotheses about dispersal mechanisms that contributed to post glacial re-establishment of ground beetles using predictions of geographic distribution patterns as metrics. I found that ground beetles were likely carried downstream by rivers which aided their dispersal northward from southern refugia. I infer from the current geographic distributions that flightless ground beetle species are still expanding their range in this boreal region. Finally, I argue that there is an urgent need for more basic research on species distributions while it is still possible in regions like northern Ontario, before increased industrial and agricultural development, and expanding resource extraction projects obliterate evidence of historic ecological processes. Author Keywords: Boreal forest, Carabidae, Coleoptera, Passive dispersal, Post-glacial distribution, Range extension
Development and Use of Passive Samplers for Monitoring Dissolved and Nanoparticulate Silver in the Aquatic Environment
Silver nanoparticles (nAg) are the largest and fastest growing class of nanomaterials, and are a concern when released into aquatic environments even at low μg L-1+). Diffusive gradient in thin films (DGT) with a thiol-modified resin were used to detect labile silver and carbon nanotubes (CNT-sampler) were used to measure nAg. Laboratory uptake experiments in lake water provided an Ag+ DGT diffusion coefficient of 3.09 x 10 -7 cm2s-1 and CNT sampling rates of 24.73, 5.63, 7.31 mL day-1, for Ag+, citrate-nAg and PVP-nAg, respectively. The optimized passive samplers were deployed in mesocosms dosed with nAg. DGT samplers provided estimated Ag+ concentrations ranging from 0.15 to 0.98 μg L-1 and CNT-samplers provided nAg concentrations that closely matched measured concentrations in water filtered at 0.22 μm. Author Keywords: ICP-MS, mesocosms, nanoparticles, nanosilver, passive sampling
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
Effects of Opioids on the Development and Reproductive Capacity of Japanese Medaka, Oryzias latipes
Opioid drugs are among the microcontaminants that are discharged with domestic wastewater into the aquatic environment with the potential to affect the development and reproductive capacity of aquatic organisms. To study the effects of exposure of fish to opioid drugs, Japanese medaka (Oryzias latipes) were exposed over a full life cycle to environmentally relevant (i.e. ng/L) concentrations of two opioids, codeine and fentanyl. Acute exposure of early life stage (ELS) of medaka to codeine resulted in slightly extended times to hatch, but no increase in embryo mortalities or reduced hatching success. Chronic exposure to codeine at a nominal concentration of 25,000 ng/L over a full life cycle interfered with growth, reducing the weight of the fish at maturity. Life cycle treatments with codeine at all test concentrations resulted in a significant reduction in the number of eggs produced in reproductive trials, as well as a reduction in the numbers of mature oocytes in adult females. High treatments with codeine also increased the percentage of immature sperm cells in adult males. Life cycle exposures to codeine also resulted in reduced whole-body concentrations of several hypothalamic-pituitary-gonadal (HPG) axis hormones, including reduced levels of luteinizing hormone in male and female fish and a reduction in 11-ketotestosterone in males and 17β-estradiol in females. Fentanyl did not affect reproduction or HPG hormones at the exposure concentrations tested, but high fentanyl exposures increased the mortality rate among ELS’s of the F1 generation offspring from life cycle exposed adults. The results of this thesis contribute to the literature on the environmental impacts of microcontaminants of wastewater origin and, the potential for effects in fish exposed to opioids.Keywords: Opioids, microcontaminants, fentanyl, codeine, sexual development, reproduction. Author Keywords: codeine, fentanyl, microcontaminants, opioids, reproduction, sexual development
Incidental Take and Population Dynamics of Nesting Birds in a Red Pine (Pinus resinosa) Plantation Under Single-Tree Selection Harvesting
I determined the direct influence of single-tree selection harvesting on the daily nest survival rates and nest success of 5 focal bird species within a monotypic red pine (Pinus resinosa) plantation on the western edge of the Oak Ridges Moraine in southern Ontario, Canada. I located and monitored 290 nests during the 2012 and 2013 breeding season. I used the logistic-exposure method to evaluate the daily nest survival rates of American Robin (Turdus migratorius), Eastern Wood-pewee (Contopus virens), Ovenbird (Seiurus aurocapilla), Rose-breasted Grosbeak (Pheucticus ludovicianus), and Red-eyed Vireo (Vireo olivaceus). Only five nests were destroyed as a result of forestry activity over the study period. Neither daily nest survival rates nor nest success of these focal species were substantially affected by single-tree selection harvesting. I also monitored the impact of single-tree selection harvesting on the density and territory size of 4 of 5 focal species. Ovenbird had a significantly smaller territory size but decreased density in the harvested areas. Although not significant, Eastern Wood-pewee and Red-eyed Vireo tended to have higher densities and larger territory sizes in harvested areas, whereas Rose-breasted Grosbeak showed a mixed effect as density was higher while territory size was smaller. Single-tree selection produces minor to moderate disturbance that takes place locally over a short period of time. As a result, nests that are indirectly disturbed by nearby harvesting, felling trees and mechanical operations and are not destroyed remain and adults do not appear to abandon eggs or young from the disturbance. Habitat alteration from harvesting of the general forest structure and especially the forest floor must be minimized in order to conserve forest bird species diversity. Further research examining incidental take using various intensities of single-tree selection harvesting would provide important insight into maintaining avian and forest diversity by means of forest management. Author Keywords: daily nest survival rates, forest management, Incidental Take, nest success, red pine monotypic forest, single-tree selection harvesting
Widespread changes in growth, diet and depth distribution of lake whitefish (Coregonus clupeaformis) in the Great Lakes are linked to invasive dreissenid mussels
Recent declines in growth and condition of Great Lakes' lake whitefish (Coregonus clupeaformis) have been linked to ecosystem-wide changes stemming from the invasion of dreissenid mussels. To test the influence of invasive mussels on this commercially important coregonid species, we collected archived scale samples from ten Great Lake locations and analyzed long-term changes in growth rates, delta 13C and delta 15N stable isotope ratios before and after mussel establishment. There was a decrease in pre-maturation growth after establishment in all four locations where we examined back-calculated growths. In six of the seven locations with dreissenid populations, a significant increase in delta 13C and a significant decrease in delta 15N was found. In dreissenid-absent locations of Lake Superior, we did not see changes in growth or isotope ratios indicative of a major regime shift. Observed shifts in isotopic signatures provide evidence for an increased reliance on nearshore food sources and shallower depth distribution as a result of dreissenids, which likely contributed to lowered growth of lake whitefish. Author Keywords: Diporeia, Dreissenids, food web, Great Lakes, invasive species, lake whitefish
Environmental structure, morphology and spatial ecology of the five-lined skink (Plestiodon fasciatus) at high latitude range limits
Detecting relevant and meaningful patterns from the complex, interconnected network of relationships between organisms and their environment is a primary objective of ecology. Ecological patterns occur across multiple scales of space and time. In this dissertation, I examine aspects of environmental structure that influence a species’ distribution and are expressed in that species’ population dynamics. I compare the morphology of the five-lined skink (Plestiodon fasciatus) near its high latitude range limits with a lower latitude population and evaluate the economics of their behaviour in the context of its reproductive strategy. I tested the conformity of this species to biogeographical rules postulated by MacArthur, Bergmann, and Rensch. Spatial ecology was investigated in the context of the environmental potential for polygamy proposed by Emlen and Oring (1977) The five-lined skink, Plestiodon fasciatus, conformed to these biogeographic rules. Specifically, abiotic factors were the primary limiting factors affecting distribution at the high latitude range limits of the species; body size was larger in high latitude populations; and the degree of sexual size dimorphism was greater at high latitude than at low latitude. Spatial ecology at the individual scale was influenced by sites with suitable thermal conditions which facilitate the polygynandrous mating system documented in P. fasciatus in high latitude populations. My results confirm the importance of microsites with suitable thermal profiles as key habitat for ectothermic vertebrates at high latitudes. The influence of temperature as a limiting abiotic factor is expressed in population density, body size, spatial ecology, and reproductive strategy of P. fasciatus. Conservation and restoration of high latitude populations of ectothermic vertebrates should focus on ensuring thermal requirements of the species of concern are met before other factors are addressed, as temperature is likely the single most important limiting factor at high latitude range limits. Author Keywords: biogeography, lizard, Plestiodon fasciatus, range limits, sexual size dimorphism, spatial ecology
Habitat use within and among roosts of chimney swifts (Chaetura pelagica)
Chimney swifts are listed as Threatened nationally and in many provinces within Canada due to rapid population declines. I examined large-scale spatial variation in the maximum size of chimney swift roosts at the northern edge of their range to identify where larger roosts occur. I used multi-sourced data collected across Ontario and Quebec between 1998 and 2013. I found that larger roosts were found at more northerly latitudes, and that very large roosts (>1000 birds) only occurred north of 45°. I also investigated fine-scale patterns of chimney swift positioning inside one of the largest roosts in Ontario. Using digitally recorded images, I calculated the angular position of swifts inside the roost relative to ambient and roost temperature. I found that swifts showed a strong preference for clinging to the south facing wall and clustered more when ambient air temperature was warmer. Thus, huddling in swifts provides additional or alternate benefits, other than serving purely to reduce costs of thermoregulation at low ambient temperatures. This research contributes to the understanding of chimney swift roosting ecology and identifies large roosting sites that should be retained for conservation. Author Keywords: chimney swift, communal roosting, conservation, group size, social thermoregulation, species-at-risk
Purification and Identification of Selenium-containing C-phycocyanin from Spirulina
Selenium is an essential trace nutrient to many organisms, yet in high concentrations it is toxic. Organic selenium is more bioavailable to aquatic biota than inorganic selenium, but is usually found in much lower concentrations. Algae are known to biotransform inorganic selenium into several organo-selenium compounds, but it is unknown whether any of these bioaccumulate in the food chain. In this study, selenium was incorporated into the methionine residues of an algal photosynthetic protein, c-phycocyanin from Spirulina spp. The extent of selenium incorporation was quantified by inductively coupled plasma-mass spectrometry (ICP-MS), and the protein was identified using electrospray mass spectrometry (ES-MS). C-phycocyanin was isolated and purified from Spirulina with a final recovery of 20-30 % of the total c-phycocyanin present. Selenomethionine replaced 92.8% ± 1.22 of the methionine residues in c-phycocyanin when grown in 2.5 ppm sodium selenite. ES-MS was used to obtain protein spectra, and pure c-phycocyanin was identified. Data of full scans provided estimated masses of both protein subunits--α-chain measured at 18,036 Da; β-chain measured at 19,250 Da--close to the theoretical masses. Protein fragmentation by collision-induced dissociation and electron capture dissociation provided approximately 52 % amino acid sequence match with c-phycocyanin from Spirulina platensis. This study demonstrates the incorporation of selenium into an algal protein, and the identification of c-phycocyanin using electrospray ionization-mass spectrometry. Author Keywords:
Characterization of Synthetic and Natural Se8 and Related SenSm Compounds by Gas Chromatography-Mass Spectrometry
Elemental selenium has been extensively quantitatively measured in sediments; however, its physical composition is largely unknown, despite it being the dominant selenium species in some reducing environments. Here, for the first time, it is shown that small, cyclic selenium compounds can account for a quantitatively-relevant fraction of the total elemental selenium present. A new method was developed to analyze for cyclooctaselenium (Se8) in both synthetic samples and selenium-impacted sediments. Despite some analytical limitations, this gas chromatography-mass spectrometry (GC-MS) method is the first GC-MS method developed to identify and quantify Se8 in sediments. Once this method was established, it was then applied to more complex systems: first, the identification of compounds in mixed selenium-sulfur melt solutions, and then the determination of SenSm in selenium-impacted sediments. Despite complications arising from pronounced fragmentation in the ion source, assignment of definitive molecular formulae to chromatographically-resolved peaks was possible for five compounds. Developing a fully quantitative method to obtain elemental ratio information can aid in the assignment of molecular formulae to chromatographically-resolved SeS-containing chromatographic peaks. Coupling the existing gas chromatography method to an inductively coupled plasma-mass spectrometer (ICP-MS) system should accomplish this. However, due to a number of complications, this was not completed successfully during the duration of this thesis project. High detection limits for sulfur, retention time discrepancies, and inconsistent injection results between the GC-MS and GC-ICP-MS system led to difficulties in comparing results between both analytical methods. Despite these limitations, GC-ICP-MS remains the most promising method for the identification and quantification of SenSm compounds in synthetic melt mixtures and selenium impacted sediments. Author Keywords: gas chromatography-mass spectrometry, sediments, selenium

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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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