Graduate Theses & Dissertations

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Nutrigenomics of Daphnia
Organismal nutrition lies at the interface between biotic and abiotic factors in an ecosystem, dictating the transfer of energy and nutrients across trophic levels. Our ability to detect nutritional limitation in consumers is reliant on a priori knowledge of dietary history due to our inability to differentiate nutrient stress based on body-wide responses. Molecular physiological responses are increasingly being used to measure physiological stress with high levels of specificity due to the specific modes of action ecological stressors have on organismal molecular physiology. Because animal consumers respond to varying nutrient supplies by up- and down-regulating nutrient-specific metabolic pathways, we can quantify nutritional status by quantifying the expression of those pathways. Here I present an investigation into the use of transcriptomics to detect nutritional stress in the keystone aquatic herbivore, Daphnia pulex, I use RNAseq and quantitative PCR (qPCR) identify nutritional indicator genes. I found that nutritional status could be determined with 100% accuracy with just ten genes. Additionally, the functional annotation of those genes uncovered previously unidentified responses to dietary stress. Further testing and validation of the selected indicator genes is required however these findings have the potential to revolutionize our ability to measure and monitor consumer nutritional stress. Author Keywords: Biomarkers, Daphnia, Gene expression, Nutrigenomics, Nutritional ecology, RNAseq
Assessing Molecular and Ecological Differentiation in Wild Carnivores
Wild populations are notoriously difficult to study due to confounding stochastic variables. This thesis tackles two components of investigating wild populations. The first examines the use of niche modeling to quantify macro-scale predator-prey relationships in canid populations across eastern North America, while the second examines range-wide molecular structure in Canada lynx. The goal of the first chapter is to quantify niche characteristics in a Canis hybrid zone of C. lupus, C. lycaon, and C. latrans to better understand the ecological differentiation of these species, and to assess the impacts of incorporating biotic interactions into species distribution models. The goal of the second chapter is to determine if DNA methylation, an epigenetic marker that modifies the structure of DNA, can be used to differentiate populations, and might be a signature of local adaptation. Our results indicated that canids across the hybrid zone in eastern North America exhibit low levels of genetic and ecological differentiation, and that the importance of biotic interactions are largely lost at large spatial scales. We also identified cryptic structure in methylation patterns in Canada lynx populations, which suggest signatures of local adaptation, and indicate the utility of DNA methylation as a marker for investigating adaptive divergence. Author Keywords: Ecological Epigenetics, Ecological Genetics, SDM
ASSESSING THE IMPACT OF ATMOSPHERIC DEPOSITION AND HARVEST INTENSITY ON SOIL ACIDITY AND NUTRIENT POOLS IN PLANTATION FORESTS
The objective of this thesis was to assess the influence of anthropogenic sulphur (S) and nitrogen (N) deposition, and harvesting on soil acidity and calcium (Ca2+), magnesium (Mg2+), potassium (K+) and N soil pools in plantation forest soils in Ireland. The response to reductions in anthropogenic S deposition was assessed using temporal trends in soil solution chemistry at two long-term monitoring plots--one on a blanket peat, the other on a peaty podzol. At the peat site, there was little evidence of a response to reductions in throughfall non marine sulphate (nmSO42-) and acidity; soil water acidity was determined by organic acids. In addition, temporal variation in soil water did not respond to that in throughfall. In the podzol, reductions in anthropogenic S and H+ deposition led to a significant improvement in soil water chemistry at 75 cm; pH increased and total aluminum (Altot) concentrations declined. The impact of harvest scenarios on exchangeable Ca2+, Mg2+ and K+ pools was assessed using input-output budgets at 40 sites (30 spruce, 10 pine). Harvest scenarios were stem-only harvest (SOH), stem plus branch harvest (SBH) and stem, branch and needle harvest (whole-tree harvesting; WTH). Average K+ and Mg2+ budgets were positive under these scenarios. However, exchangeable K+ pools were small and due to uncertainty in K+ budgets, could be depleted within one rotation. Average Ca2+ budgets for spruce were balanced under SOH, but negative under SBH and WTH. Nitrogen deposition was high, between 5 and 19 kg N ha-1 yr-1, but was balanced by N removal in SOH. However, N budgets were under SBH and WTH, indicating that these harvesting methods would lead to depletion of soil N over the long-term. Finally, monitoring of N cycling at a spruce plot indicated that N deposition was contributing to large NO3- leaching, and as such the site was N saturated. However, N cycling did not fit the criteria of the N saturation hypothesis; instead leaching was directly related to N deposition and supported the model of kinetic N saturation. Author Keywords: acidic deposition, base cations, input-output budgets, Ireland, nitrogen, whole-tree harvesting
Islands, ungulates, and ice
Central to wildlife conservation and management is the need for refined, spatially explicit knowledge on the diversity and distribution of species and the factors that drive those patterns. This is especially vital as anthropogenic disturbance threatens rapid large-scale change, even in the most remote areas of the planet. My dissertation examines theinfluence of land- and sea-scape heterogeneity on patterns of genetic differentiation, diversity, and broad-scale distributions of island-dwelling ungulates in the Arctic Archipelago. First, I investigated genetic differentiation among island populations of Peary caribou (Rangifer tarandus pearyi) in contrast to continental migratory caribou (Rangifer tarandus) and evaluated whether genetic exchange among Peary caribou island populations was limited by the availability of sea ice – both now and in the future. Differentiation among both groups was best explained by geodesic distance, revealing sea ice as an effective platform for Peary caribou movement and gene flow. With future climate warming, substantial reductions in sea ice extent were forecast which significantly increased resistance to caribou movement, particularly in summer and fall. Second, I assessed genetic population structure and diversity of northern caribou and deciphered how Island Biogeography Theory (IBT) and Central Marginal Hypothesis (CMH) could act in an archipelago where isolation is highly variable due to the dynamics of sea ice. Genetic differentiation among continental and island populations was low to moderate. In keeping with IBT and CMH, island-dwelling caribou displayed lower genetic diversity compared to mainland and mainland migratory herds; the size of islands (or population range) positively influenced genetic diversity, while distance-to-mainland and fall ice-free coastlines negatively influenced genetic diversity. Hierarchical structure analysis revealed multiple units of caribou diversity below the species level. Third, I shifted my focus to the terrestrial landscape and explored the elements governing species-environment relationships. Using species distribution models, I tested the response of caribou and muskoxen to abiotic versus abiotic + biotic predictors, and included distance to heterospecifics as a proxy for competitive interactions. Models that included biotic predictors outperformed models with abiotic predictors alone, and biotic predictors were most important when identifying habitat suitability for both ungulates. Further, areas of high habitat suitability for caribou and muskoxen were largely disjunct, limited in extent, and mainly outside protected areas. Finally, I modelled functional connectivity for two genetically and spatially disjunct groups of island-dwelling caribou. For High Arctic caribou, natural and anthropogenic features impeded gene flow (isolation-by-resistance); for Baffin Island caribou we found panmixia with absence of isolation-by-distance. Overall, my dissertation demonstrates the varying influences of contemporary land- and sea-scape heterogeneity on the distribution, diversity and differentiation of Arctic ungulates and it highlights the vulnerability of island-dwelling caribou to a rapidly changing Arctic environment. Author Keywords: Circuitscape, connectivity, Island Biogeography, landscape genetics, population structure, species distribution models
Combining Line Transect Sampling and Photographic-Identification Surveys to Investigate the Abundance and Distribution of Cetaceans
Line transect sampling and photographic-identification (photo-ID) are common survey techniques for estimating the abundance and distribution of cetaceans. Combining these approaches in the field (‘combined LTPI’ surveys) and using data from both components has the potential for generating comprehensive ecological knowledge that can be far more valuable than when these techniques and their data are used independently. In this thesis, I evaluated the results and conclusions from these two methods, used singly and in tandem, by investigating the population dynamics of two humpback dolphin (Sousa chinensis spp.) populations: the large and widely distributed Chinese white dolphin (S. c. chinensis) of the Pearl River estuary (PRE), and the small and geographically isolated subspecies of Taiwanese white dolphin (S. c. taiwanensis) in the eastern Taiwan Strait. Data from combined LTPI surveys in Hong Kong waters, at the eastern edge of the PRE, revealed a shift in space use with individuals spending less time in these waters than at the start of surveys. Data from combined LTPI surveys in Taiwan provided further support for a subspecies restricted to the central western waters, and identified a commonly used area at the northern part of their limited range. These two case studies demonstrated an overall efficacy of combined LTPI surveys in ecological studies of cetaceans. However, a multi-criteria analysis revealed that combined LTPI surveys with a line transect focus (e.g., Hong Kong) performed better than a LTPI survey with a photo-ID focus (e.g., Taiwan) when considering ecological aspects of the study populations, labour and data requirements, and ecological output. Even so, the photo-ID focus of Taiwan’s monitoring program led to better assessments of individual space use patterns, likely helped by the Taiwanese white dolphin population’s smaller size and intensive photographic effort. In both cases, the ecological output of combined LTPI surveys could be improved by expanding the study area or extending the field season or frequency of surveys. Overall, I showed that by following a set of general guidelines, different iterations of the combined LTPI approach (i.e., photo-ID focus or LT focus) can serve as powerful tools for uncovering multi-dimensional ecological information on cetaceans. Author Keywords: abundance, cetacean, distribution, line transect sampling, multi-criteria analysis, Photo-ID
Shorebird Habitat Use and Foraging Ecology on Bulls Island, South Carolina During the Non-Breeding Season
Recent declines in North American shorebird populations could be linked to habitat loss on the non-breeding grounds. Sea-level rise and increased frequency of coastal storms are causing significant erosion of barrier islands, thereby threatening shorebirds who rely on shoreline habitats for foraging. I conducted shorebird surveys on Bulls Island, South Carolina in the winters of 2018 and 2019 and examined habitat selection and foraging behaviour in Dunlin (Calidris alpina), Sanderling (Calidris alba), Semipalmated Plovers (Charadrius semipalmatus), and Piping Plovers (Charadrius melodus). Area, tidal stage, and invertebrate prey availability were important determinants of shorebird abundance, behaviour, and distribution. My study highlights the importance of Bulls Island’s habitat heterogeneity to supporting a diverse community of non-breeding shorebirds. Considering both the high rate of erosion and the increased frequency of disturbance along the shoreline of the island, intertidal habitats should be monitored to predict negative effects of changes in habitat composition and area on non-breeding shorebirds. Author Keywords: foraging behaviour, habitat loss, habitat selection, invertebrate prey, non-breeding, shorebirds
Discriminating grey wolf (Canis lupus) predation events in a multi-prey system in central Saskatchewan
I investigated if spatio-temporal behaviour of grey wolves (Canis lupus) determined via GPS collar locations could be used to discriminate predation events generally, and among prey species, in Prince Albert National Park during winter, 2013-2017. I used characteristics of spatio-temporal GPS clusters to develop a predictive mixed-effect logistic regression model of which spatial clusters of locations were wolf kill sites. The model suffered a 60 % omission error when tested with reserved data due to the prevalence of deer kills with correspondingly low handling time. Next, I found a multivariate difference in the percentage of habitat classes used by wolves in the 2 hours preceding predation events of different prey species, suggesting that wolf habitat use reflects prey selection at a fine-scale. My results highlight the difficulty and future potential for remoting discriminating wolf predation events via GPS collar locations in multi-prey ecosystems. Author Keywords: Canis lupus, GPS clusters, GPS collars, grey wolf, habitat use, predation
Determinants of Breeding Bird Diversity in Ontario's Far North
190 species of birds are known to breed in Ontario’s far north making the region an important nursery for boreal birds. Digital point count data were collected using two different autonomous recording units (ARUs): one model with two standard microphones to detect birds and anurans, and one model with one standard microphone and one ultrasonic microphone for detecting bats. ARUs were deployed either in short or long-term plots, which were four to six days or approximately 10 weeks, respectively. I assessed differences in breeding bird richness detections between ARU and plot types. I also tested the relative impact of the habitat heterogeneity and species-energy hypotheses in relation to breeding birds and created predictive maps of breeding bird diversity for Ontario’s far north. I found no difference in species richness estimates between the two ARU models but found that long-term plots detected about 7 more bird species and 1.5 more anuran species than short-term plots. I found support for both the species-energy and habitat heterogeneity hypotheses, but support for each hypothesis varied with the resolution of the analysis. Species-energy models were better predictors of breeding bird diversity at coarser resolutions and habitat heterogeneity models were better predictors at finer resolutions. Breeding bird diversity was highest in the Ontario Shield Ecozone compared with the Hudson Bay Lowlands Ecozone, but concentrated areas of higher diversity found in the Lowlands were associated with large rivers and the associated coastlines. Author Keywords: boreal birds, breeding birds, habitat heterogeneity, Hill diversity, Ontario, species-energy hypothesis
Biodiversity patterns along a forest time series in a remediated industrial landscape
Sudbury, Ontario is an epicenter of research on industrially degraded landscapes. Regreening efforts over the past 40 years have changed the landscape, leading to an increase in forest cover in the “barrens”, that once covered more than 100,000 ha. This study characterized changes in plant and insect composition using a space for time approach in the pine plantations. A total of 25 treated sites were sampled and soil characteristics, understory plants and insect communities were assessed. All sites were contaminated with copper and nickel, but the metals had little influence on biodiversity. Vegetation diversity metrics were more strongly correlated with the pH of the organic soil horizons, while the insect community shows little response to site characteristics, and rather vegetation cover. Plant composition changes are similar to those in pine stands undergoing natural recovery and as liming effects fade there may be a decline in insect community richness. Author Keywords: Biodiversity, Heavy Metals, Mining, Remediation
multi-faceted approach to evaluating the detection probability of an elusive snake (Sistrurus catenatus)
Many rare and elusive species have low detection probabilities, thereby imposing unique challenges to monitoring and conservation. Here, we assess the detection probability of the Eastern Massasauga (Sistrurus catenatus) in contrast to a more common and conspicuous species, the Eastern Gartersnake (Thamnophis sirtalis). We found that patterns of detection probability differed between species, wherein S. catenatus was detected less often and under a more specific set of sampling conditions. Correspondingly, detection trials with S. catenatus found a high non-detection rate, while detection trials with artificial models suggest that regional differences in detection probability are driven by variation in population density and habitat use. Our results suggest that current monitoring efforts are not sufficient, and that S. catenatus is frequently undetected. Accordingly, we highlight the importance of species-specific monitoring protocols when monitoring rare and elusive species, and recommend a multi-faceted approach that estimates detection probability and identifies species-specific challenges to monitoring. Author Keywords: detection probability, elusive species, monitoring programs, non-detection, S. catenatus, snakes
Evaluating the Effects of Habitat Loss and Fragmentation on Canada Lynx
Current major issues in conservation biology include habitat loss, fragmentation and population over-exploitation. Animals can respond to landscape change through behavioural flexibility, allowing individuals to persist in disturbed landscapes. Individual behaviour has only recently been explicitly included in population models. Carnivores may be sensitive to changing landscapes due to their wide-ranging behaviour, low densities and reproductive rates. Canada lynx (Lynx canadensis) is a primary predator of snowshoe hares (Lepus americanus). Both species range throughout the boreal forests of North America, however lynx are declining in the southern range periphery. In this dissertation, I developed new insights into the effects of habitat loss and fragmentation on lynx. In Chapter 2, I created a habitat suitability model for lynx in Ontario and examined occurrence patterns across 2 regions to determine if habitat selection is flexible when different amounts of habitat are available. Although lynx avoided areas with <30% suitable habitat where suitable land cover is abundant, I found that they have flexible habitat selection patterns where suitable land cover is rare and occurred in low habitat areas. In Chapter 3, I investigated the effects of dispersal plasticity on occupancy patterns using a spatially explicit individual-based model. I showed that flexible dispersers, capable of crossing inhospitable matrix, had higher densities and a lower risk of patch extinction. In contrast, inflexible dispersers (unable to cross inhospitable matrix), were most limited by landscape connectivity, resulting in a high extinction risk in isolated patches. I developed three predictions to be explored with empirical data; (1) dispersal plasticity affects estimates of functional connectivity; (2) variation in dispersal behaviour increases the resilience of patchy populations; and (3) dispersal behaviour promotes non-random distribution of phenotypes. Finally, in Chapter 4, I examined the consequences of anthropogenic harvest on naturally cycling populations. I found that harvest mortality can exacerbate the effects of habitat fragmentation, especially when lynx densities are low. Dynamic harvest regimes maintained lynx densities and cycle dynamics while reducing the risk of population extinction. These results suggest that lynx display some flexibility to changing landscapes and that the metapopulation structure is more resilient to increasing habitat loss and fragmentation than previously understood. Future studies should focus on determining a threshold of connectivity necessary for population persistence and examining the effects of habitat loss on the fecundity of lynx. Author Keywords: Fluctuating Populations, Habitat Fragmentation, Landscape Ecology, Occupancy Dynamics, Population Ecology, Spatially Explicit Population Models
Assessing and Mitigation the Impacts of Mining-induced Flooding on Arctic-nesting Birds
Mining and resource development are growing industries in the Arctic, resulting in increased conflict with wildlife. Best practices for mitigation require an understanding of the potential ecological effects. One such effect concerns the flooding of terrestrial bird habitat from dewatering of lakes during mining pit development. I first assessed the efficacy of bird deterrents to mitigate impacts of mining-induced flooding on arctic-nesting birds at a gold mine in Nunavut. I used a Before-After Control Impact (BACI) design to determine changes in male territory densities, between year and treatment types (Control, High and Low Deterrent Intensity). Additionally, I assessed whether deterrents impacted daily survival rates of two passerine species, and the incubation behaviour of female Lapland Longspur. Finally, I quantified nest losses during the breeding season due to direct flooding of the tundra nesting habitat caused by mining operations. Deterrents did not affect male territory densities and neither deterrent treatment nor year affected the daily survival rate of nesting passerines. Female Lapland Longspurs exposed to deterrents exhibited more incubation off-bouts than control females. I documented six flooded nests. Deterrents used in this study appear to be ineffective in mitigating nesting in potential zones of impact. Incidental take accounted for about 1.2% of all nests found in the 0.48 km2 Whale Tail Lake study area. Author Keywords: arctic-nesting birds, audio deterrents, incidental take, mining and resource development, nest incubation, visual deterrents

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