Graduate Theses & Dissertations

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Genetic diversity and differentiation of Ontario’s recolonizing fishers (Pekania pennanti)
Fishers (Pekania pennanti) were extirpated from many parts of Ontario in the early 20th century, but as of the early 2000s the species had recolonized most of its historical range. While the primary population genetic structure of fishers in central and eastern Ontario has not changed drastically over the past ten years, we did find evidence of increased secondary structure and a reduction in northward movement from southeastern Ontario, a site of recent immigration from the Adirondacks in northern New York. This may be indicative of a reduction in density and thus in density-dependent migration, or it may be a consequence of the population reaching equilibrium following a period of rapid expansion associated with recolonization. We also observed no variation within central and eastern Ontario at 14 of 15 candidate functional loci we screened, suggesting possible directional or stabilizing selection and a lack of adaptive potential. Author Keywords: fisher, functional genes, Ontario, Pekania pennanti, population genetics, recolonization
Investigating Ecological Niche Differentiation Among Wild Candids Experiencing Hybridization in Eastern North America
Currently there are large areas of the North American landscape that are occupied by Canis spp. hybrids of several varieties, leading to the logical question as to the genetic structure and ecological function of Canis populations across the continent, and to what extent hybrids reflect contemporary landscapes. This study illustrated patterns of niche differentiation between parental canid species and their hybrids using individual high quality genetic profile and species distribution models to support the intermediate phenotype hypothesis. In general, hybrids demonstrated an intermediate habitat suitability compared to its parental species, across most environmental variables used. A similar trend was observed in the niche metric analysis, where we found that hybrids exhibit intermediate niche breadth, with eastern coyotes and eastern wolves exhibiting the broader and narrower niche, respectively. Our results demonstrate that the intermediate phenotype hypothesis is supported even at a large scale and when involving highly mobile large mammal species. Author Keywords: canid, ecological niche modelling, hybridization, intermediate phenotype, microsatellite genotype, niche differentiation
Mixed methods approaches in marine mammal science
This thesis explored the contribution of mixed methods approaches to marine mammal science through the use of concurrent and sequential designs to study distribution and feeding ecology of bowhead whales (Balaena mysticetus) in the Arctic region of Nunavik, Quebec, Canada. The study combines Inuit knowledge (IK), collected through semi-directed interviews with Inuit harvesters, and analyses of stable isotopes and trace elements (SI/TE) in baleen plates. A systematic literature review found that mixed methods are increasingly used in marine mammal ecology studies in remote locations, yet are still relatively rare and face a number of challenges. Both IK and SI/TE, indicated that bowhead whales have a seasonal pattern in their distribution and feeding ecology. They are most commonly present in productive nearshore areas in summertime, feeding in areas of great prey diversity, and moving to offshore areas in winter to fast. Mixed methods approaches used in this case study enabled the collection of complementary knowledge about bowhead whale ecology important for local management in a changing climate. This study also shows the value of mixed methods approaches for future marine mammal studies in Nunavik and elsewhere. Author Keywords: Arctic, bowhead whale, distribution, feeding ecology, mixed methods, traditional ecological knowledge
Novel Silica Sol-Gel Passive Sampler for Mercury Monitoring in Aqueous Systems
A novel passive sampler for mercury monitoring was prepared using organosilica sol-gel materials. It comprises a binding layer with thiol groups for mercury complexation and a porous diffusive layer through which mercury can diffuse and arrive at the binding layer. Our study demonstrated that this new sampler follows the principle of passive sampling. The mass of mercury accumulated in the binding layer depends linearly on the mercury concentration in solution, the sampling rate and the exposure time. A typical sol-gel sampler is characterized by a diffusive layer of 1.2 &mum, in which mercury ions diffuse with a coefficient of D = 0.09~10-6 cm2/s. The capacity for mercury uptake is approximately 0.64 &mug/cm2. Mercury diffusion and binding in the passive sampler are independent of the type of mercury-chloride complex. Its sampling rate increases with increasing water turbulence and decreases with increasing DOM amount. The field trial of sol-gel sampler in Miller Creek shows the concentration gained from the sol-gel passive sampler is slightly lower than that from the spot sampling. Author Keywords:
Scarring, sex assignment, and sex-specific sociality of Indo-Pacific humpback dolphins (Sousa chinensis) in the Pearl River Estuary and eastern Taiwan Strait
The Pearl River Estuary (PRE) and eastern Taiwan Strait (ETS) populations of Indo-Pacific humpback dolphins (Sousa chinensis) contain ~600 and 100 catalogued individuals, respectively. Population demography is important for conservation actions but few animals have been sexed by conventional methods. Longitudinal analysis of tooth-rake scars on dorsal fins showed scars disappear within 7 months; sexing adults by scarring is likely not impacted by juvenile scarring. Using dorsal fin photographs, sex assigned for 87% of catalogued PRE adults (n=300) and for 93% of ETS adults (n=60), using scars hypothesized from male-male competition, was in concordance with sex assigned by DNA, calf association, and ventral photographs. Scarring was higher in presumed males than females and in PRE females than ETS females. Female:male sex ratios were 3:2 (PRE) and 2:1 (ETS), though this likely results from biases in photo-identification methods. Social analysis with presumed sexes showed strong female-female associations in both populations but stronger female-male and male-male associations in PRE. These results support sex differentiation by scarring, which was a non-invasive approach, and sex assignment for many PRE and ETS individuals. Author Keywords: Indo-Pacific humpback dolphins, photo-identification, scarring, sex differentiation, sexes, social structure
Influence of nitrogen deposition on the vegetation community of Irish oak woodlands
In this study, the influence of N deposition on the vegetation community of semi-natural oak woodlands in Ireland was assessed through national and regional scale analysis of forest plot data. At both scales, Canonical Correspondence Analysis suggested that N deposition was a predictor of community composition, although site-specific soil characteristics were the strongest predictors of the species dataset. Threshold Indicator Taxon Analysis suggested that the vegetation community demonstrated the most change at 13.2 kg N ha-1 yr-1. While this change point falls within the current recommended critical load range for nutrient nitrogen for acidophilous oak dominated woodlands (10 to 15 kg N ha-1 yr-1), it is notable that 23% of species recorded had individual change points below this range, and could potentially be lost from this habitat if deposition increases. The results from this study suggest that, for acidophilous oak woodlands, habitat conservation policies should be unified with N emission reduction policies. Author Keywords: community composition, critical load, nitrogen depositioin, oak woodland, species richness, Taxon Indicator Threshold Analysis
HABITAT SELECTION AND LIFE-HISTORY TRAITS OF BREEDING BIRDS IN THE BOREAL-TUNDRA ECOTONE, WITH SPECIAL ATTENTION TO THE AMERICAN ROBIN (TURDUS MIGRATORIUS)
I investigated biodiversity of birds and vegetation associations along the boreal-tundra ecotone in Ivvavik National Park, Yukon Territory, and breeding adaptations used by American Robins (Turdus migratorius) at high latitudes. Twenty bird species were detected over three years using point-count surveys. Densities of American Robin, Dark-eyed Juncos (Junco hyemalis), and Yellow-rumped Warbler (Dendroica coronata) had positive relationships with tree and shrub density, whereas density of White-crowned Sparrows (Zonotrichia leucophrys) was negatively related to tree density. American Robins at this latitude raised only one brood, but females laid slightly larger clutches, the young fledged earlier, and pairs experienced higher nest-success than American Robins at more southerly latitudes. American Robins selected nest sites with high vegetation volume, at both the nest-site, and the nest-patch. This study is important for the first description of the bird community at this high latitude location, and describing how a species at the northern limit of the boreal forest has adapted to living with short-breeding seasons. Author Keywords: American Robin, Ivvavik National Park, Life History, Nest-stie selection, Northern limit
Fractionation of Mercury Isotopes in an Aqueous Environment
Fractionation of mercury isotopes in an aqueous environment: Chemical Oxidation Dimitri Stathopoulos The study of fractionation patterns for the stable isotopes of mercury is a growing field. The potential for stable isotopes to trace mercury through the environment from pollution sources to sinks make the subject interesting to geochemists and useful to a wider audience. The purpose of this study is to measure the fractionation of mercury as it is oxidized in an aqueous medium. Samples in this study are prepared by chemically oxidizing different proportions of elemental mercury using four different oxidants. The oxidized portion is then separated from the elemental portion and an analysis of the isotope ratios for both portions is performed using a multicollector inductively coupled plasma mass spectrometer MC-ICP/MS. These isotope ratios are measured against the preoxidation isotope ratio to determine what if any change has occurred. From the findings of this work, it is now known chemical oxidation causes both mass dependent and mass independent fractionation. Mass dependent fractionation causes an enrichment of the heavier isotopes in the oxidized portion while the opposite is true for the elemental portion. Mass independent fractionation occurred only in the odd isotopes and causes a depletion of odd isotopes in the oxidized portion and enrichment in the elemental portion. These trends were found to be true for all oxidants tested as the pattern of fractionation does not change with varying oxidants. Author Keywords: Isotope, Mass Dependent, Mass Independent, Mercury, Oxidation
THE LIFE HISTORY STRATEGY, GROWTH, BODY CONDITION, AND DIET OF STOCKED AMERICAN EEL (Anguilla rostrata) IN THE UPPER ST. LAWRENCE RIVER AND LAKE ONTARIO
My study was primarily focused on the comparison of life history traits between stocked American eel and their naturally recruited conspecifics in Lake Ontario and the upper St. Lawrence River (USLR/LO). I found that stocked eels experienced faster annual growth than their naturally recruited conspecifics and were comprised of a greater proportion of males. These findings indicate that the life history patterns of American eel may be genetically predisposed. Additionally, my study served to characterize the diets of stocked American eel and examine possible associations between eel and prey size. The eels consumed a number of macroinvertebrate prey orders as well as fishes and macrocrustaceans, with the latter prey items being more prevalent in the diets of larger eel specimens. A disparity in eel growth and body condition was observed between two primary stocking locations and were likely attributable to differences in available forage and habitat. Lastly, growth, body condition, and stocked eel diet were compared between lentic and lotic habitats. Eels from lotic streams experienced slower annual growth and had reduced body condition, and their diets were comprised of smaller prey items. The results of this study suggest that the current stocking methods employed in the USLR/LO are not suitable to restore the natural recruitment of individuals that will exhibit desired life history traits. Author Keywords:
Analysis and reactions of aqueous selenide and other reduced inorganic selenium compounds under anoxic conditions
Selenide is cited as a geochemically important selenium (Se) species, but it is unknown whether selenide is a stable aqueous ion in natural waters. The feasibility of using anoxic anion exchange chromatography (AEC) coupled to dynamic reaction cell-inductively coupled plasma-mass spectrometry to separate aqueous selenide was investigated with the goal of quantifying this anion to determine its importance in reducing waters. It was possible to qualitatively identify selenide using AEC, but much of the aqueous selenide oxidises to Se0 faster than the separation procedure could be completed. AEC analyses of solutions containing polyselenides produced peaks for unidentified Se compounds, which have been assigned tentative structures Se2O22-, Se2O32-, and Se2O62- based on close matches in retention time to stable S compounds. The results of this work show that aqueous selenide can be qualitatively observed in synthetic solutions using AEC, but it is unknown whether these conditions are relevant to natural waters. Author Keywords: anoxic speciation, polyselenides, selenide, selenium geochemistry, selenium speciation, selenoselenate
Influence of Habitat on Woodland Caribou Site Fidelity
Site fidelity is the behaviour of individuals to return to the same location; for female woodland caribou it may reflect reproductive success and depend on habitat quality. I investigated the influence of landscape and disturbance conditions on fidelity among three populations in Manitoba and Ontario, Canada. Habitat classifications were based on Forest Resource Inventory (FRI) and Landsat TM landcover maps. A total of 261 sites were ground-truthed to determine mapping accuracy. An amalgamated map incorporating FRI and Landsat TM data was estimated from field measurements to have an overall accuracy of 69.0%. Site fidelity was expressed as the distance between consecutive-year locations of individuals and was investigated during five week-long periods representing calving, early and late post-calving, winter, and breeding. Site fidelity was strongest during the post-calving seasons and weakest during the winter. Habitat had little influence on site fidelity in all seasons, excepting winter, even under highly disturbed conditions, suggesting maintenance of fidelity may be a maladaptive trait. Individual variation proved a strong predictor and cursory mapping indicated that caribou may return to sites visited two or more years earlier. Conservation management and policy should recognize that site fidelity may represent an ecological trap. Author Keywords: calving, disturbance, habitat, movement, Rangifer tarandus caribou, site fidelity
Tabanidae and Culicidae in the Northern Boreal Region of Ontario
I studied the abundance, distribution and diversity of horse fly and deer fly species (Diptera: Tabanidae) and mosquito species (Diptera: Culicidae) in the boreal forest region of northern Ontario in 2011 and 2012. I collected 19 mosquito species, including one species new for Ontario, Aedes pullatus (Coquillett). I documented 11 northern and one southern range extension. I also collected a total of 30 species of horse and deer flies, including one new species of horse fly for Ontario, Hybomitra osburni (Hine). Results were inconsistent with a hypothesis of colonization of dipteran species from west to east. I examined the trapping biases of Malaise and sweep sampling for horse and deer flies and found that Malaise traps collected fewer individuals than sweep netting (850 versus 1318) but more species (28 versus 22). Consequently, I determined that surveys of diversity benefit from the use of multiple trapping methods. I also examined how blood-feeding (anautogeny) requirements affect the distribution patterns of Tabanidae. Ultimately, there are likely multiple factors that affect the expression of anautogeny in Tabanidae. Author Keywords: Autogeny, Culicidae, Diversity, Hudson Bay Lowlands, Northern Ontario, Tabanidae

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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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