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The remote, ice-covered habitat and reclusive nature of Arctic cetaceans have led to a gap in knowledge about species ecology. In rare instances where Arctic cetaceans can be spotted, information about their population structure and biology can be gleaned through observation; however, direct observations are difficult in high ice cover. Ice entrapments, where cetaceans are crowded under increasing ice cover until escape or drowning, have given insight into cetacean populations since the 18th century, and today new genetic analyses can allow us to reexamine the population structure of these Arctic species and add to previous research on ice entrapments and narwhal social structure. In this thesis’ second chapter, I first review 138 cetacean ice entrapment occurrences globally and show that ice entrapments are a significant source of mortality for cetaceans, killing more than 18,500 individuals in 13 different species since 1900. In the third chapter, I use population genetics to study the social structure of the Canadian Arctic narwhal (Monodon monoceros) from a 2008 ice entrapment. Through pair-wise relatedness and cluster analysis, I determined that within an ice-entrapped herd (n=245), there were 8 genetically related clusters with an average size of 30.6, indicating that the species may follow a fission-fusion social structure like other smaller, social cetaceans. This work may contribute to species management decisions and be valuable for emergency management of ice entrapments.

The diversification of flowering plants has been described as the “abominable mystery” of evolutionary biology for decades. Angiosperms diversified at unprecedented rates in the early Cretaceous, rapidly occupying new niches and pervading much of the earth’s terrestrial landscape. This speciation was accompanied by dramatic genome evolution as well — more than 75% of extant angiosperm species are believed to have originated from genome duplication events. These duplications are most often in the form of endogenous chromosomal duplication (autopolyploidy) or, more frequently, via interspecific hybridization (allopolyploidy). Consequently, dynamics of polyploidy within flowering plants are of interest to the fields of plant genetics and evolution. One of the world’s most important oilseeds is Brassica napus L. (“canola”), an allopolyploid species derived from two progenitors (B. rapa and B. oleracea). B. napus has two relatively complete diploid genomes from each progenitor, but also shares a whole genome triplication (autopolyploidization) with the rest of the Brassicaceae. These factors constitute B. napus as an informative model to study the consequences of polyploidization. Within this thesis, I describe the transcriptional and epigenetic profiles throughout B. napus seed development. Therein, I utilize laser microdissection, histological analysis, and bioinformatic tools to describe the transcriptional profiles of the seed. The subgenomes constituting B. napus contribute to gene expression within the seed asymmetrically, with many homlogs being more expressed in one subgenome than the other. Additionally, I provide evidence for striking differences in epigenetic structure of the fractionated genomes depending on genomic context. The works detailed within this thesis serve to explain the transcriptional landscapes of the B. napus seed, particularly through the lens of polyploidy, and the exceptional complexity of angiosperm genomes.

The sterile insect technique (SIT) is a chemical-free approach to insect control that involves the mass release of sterile male insects into natural populations to reduce the number of offspring in subsequent generations by outcompeting wild males during mating. SIT has been effective against various insect species, but for the mosquito Aedes aegypti, eliminating females from the pool of sterile males is crucial for successful large-scale release programs. Current methods rely on automated sorting to separate larger female pupae from smaller males before sterilization. However, these methods still suffer from high levels of female contamination, which could worsen disease transmission. Notably, female Aedes aegypti pupae are not only larger but also emerge later than males, suggesting that sex-specific genes play a role in larval development. Identifying and targeting these genes using RNA interference (RNAi) technology could potentially alter larval development and be useful for SIT. Through transcriptomic analyses, 168 female-biased transcripts were identified, of which we selected 33 for RNAi knockdown experiments using gene-targeting short-hairpin RNA (shRNA). The results demonstrated that knocking down 23 of these genes had a significant impact on larval development, a subset of which drastically altered pupation times between males and females. These differences could aid sex-sorting efforts by allowing a higher proportion of male-only pupae to be collected before any females emerge, potentially improving the effectiveness of SIT for mosquito control.

Many pollinators visit multiple plant species, causing pollinators to carry and deposit diverse pollen loads. Although interspecific pollen transfer is ubiquitous, few studies have tested how pollen load composition and donor identity affect plant fitness. First, pollen from close relatives may decrease reproductive success due to their ability to germinate, clog pistils and usurp ovules, whereas pollen from distantly related donors may have negligible effects. Second, when pollen receipt is low, flowering neighbours may enhance pollinator visitation and cause a positive relationship between conspecific and heterospecific pollen deposition. I investigated the fitness consequences of pollen donor-recipient relatedness and pollinator sharing in two populations of a subalpine herb with diverse pollinators, Polemonium brandegeei, and its co-flowering communities. First, I collected open pollinated stigmas from all abundant co-flowering species in the communities. To test the prediction that pollinator sharing would be common in my study communities I used pollen transfer networks and floral visitor networks. Pollinator sharing was common between co-flowering species at CO-DM and WY-VD in 2022. All sampled species received or donated heterospecific pollen; most species, however, received little heterospecific pollen in each pollen load. Partial exclusion experiments revealed that both large pollinators (hummingbirds and hawkmoths) and small pollinators (bees and flies) contributed to outcrossed conspecific pollen and heterospecific pollen deposition. Second, I explored the fitness consequences of pollinator sharing and interspecific pollen transfer. Type II regressions between heterospecific pollen and conspecific pollen number and germination revealed that only neutral and facilitative relationships occurred between co-flowering species. To test the prediction that congeneric donors decrease P. brandegeei pollen germination and seed set, I conducted experimental hand po

The loss and degradation of freshwater habitats in Canada threaten the rich array of plant and animal species supported within these ecosystems, threatening the biodiversity that these ecosystems sustain. Assessing the distribution of the species in these threatened ecosystems is necessary for the effective monitoring of the well-being of their populations and the ecosystem, but it can be difficult, as some species can evade traditional survey methods due to their elusiveness, size, range, or rarity. Environmental DNA (eDNA), which describes the pool of DNA present in an environment that can be collected in and isolated from environmental samples, offers an alternative to traditional surveying that can be more sensitive and less invasive. Therefore, I developed and validated TaqMan™ MGB probe-based eDNA assays for six freshwater fishes of conservation concern in Manitoba: Bigmouth Buffalo Ictiobus cyprinellus, Chestnut Lamprey Ichthyomyzon castaneus, Golden Redhorse Moxostoma erythrurum, Hornyhead Chub Nocomis biguttatus, Northern Brook Lamprey Ichthyomyzon fossor, and Silver Lamprey Ichthyomyzon unicuspis. The designed assays were validated in situ using paired eDNA and capture-based sampling and used to map the distribution of the above species from water samples collected and filtered from 129 sites across Manitoba in 2021–2023. I detected the eDNA of four of the target species outside of their historic range: Bigmouth Buffalo in the Roseau, Morris, and Assiniboine rivers; Golden Redhorse in Hazel Creek; Hornyhead Chub in waterbodies of the Winnipeg River watershed where it has not been reported previously; and Northern Brook Lamprey in Boggy River. Apart from Northern Brook Lamprey, the eDNA of all target species was not detected in at least one site within their historic range. Further research is needed to confirm if the lack of eDNA detections of the target species within their historic range is a result of range restriction, or if a refinement of the methods

Arctic terrestrial ecosystems are some of the most extreme environments on earth, with a polar climate and landscapes recently carved by glacial retreat. Soil nutrient availability is a limiting factor for tundra productivity and under these conditions, the impacts of consumer-driven nutrient cycling can be magnified. Arctic foxes (Vulpes lagopus) are predators that act as ecosystem engineers in arctic and alpine tundra heath by altering the environment of their den sites, which exhibit increased soil nutrients, verdant atypical vegetation, and deeper snow. These fox dens are biogeochemical hotspots in otherwise nutrient-limited ecosystems and sources of cascading effects across trophic levels. It has been long hypothesized that these dens are so biotically productive because Arctic foxes increase the deposition rate of limiting nutrients by concentrating prey-derived nitrogen (N) and phosphorus (P) in the soil and this hypothesis has been descriptively supported but, the mechanism had not been confirmed with experimentation. To test the ability of the nutrients concentrated by Arctic foxes to cause the ecosystem effects observed on fox dens, I examined a long-term field experiment in Wapusk National Park. Vegetation plots received N and P additions (estimated from fox activity) and/or snow fencing on the windward side to increase snow depth. I investigated how the species composition of plot plant communities changed over 5 years, the treatment effects on plant productivity, intraspecific changes in prostrate shrub leaf metabolism, the response of resident insect communities, and the space use by collared lemmings. I found that nutrient addition facilitates the invasion of tall grass that can accumulate deep snow cover in the winter, deep snow can magnify some effects of increased nutrients, and the nutrient/snow combination can shape plant communities and create preferred lemming habitat. My thesis demonstrates how N and P deposition, increased to a rate within th

Worldwide, mosquitoes are of great medical and economic importance due to their profound negative impact on humans. Mosquitoes act as both nuisance pests and disease vectors that account for millions of cases of illness and death annually. They rely on complex olfactory systems for many of their fundamental processes such as finding mates, identifying egg-laying sites, and directly linked to their disease vectoring capabilities, locating blood-meals. Their olfactory systems rely on three major categories of receptors: odorant receptors, ionotropic receptors, and gustatory receptors. These receptors, along with sensors of various environmental cues such as CO2, heat, and humidity, contribute to the mosquito’s chemosensory responses. The yellow fever mosquito, Aedes aegypti, is responsible for the transmission of key diseases such as dengue virus, yellow fever virus, chikungunya virus, and Zika virus. Because of its profound impacts on human health, there is growing interest in exploring new ways to disrupt Ae. aegypti’s olfactory-based behaviours as a means of reducing disease transmission. While there are numerous studies focused on adult mosquito chemoreception, little is known about these processes in mosquito larvae. Here, a chemotaxis response assay was developed to examine which naturally occurring chemicals would attract Ae. aegypti larvae. Mosquito larvae were subsequently fed E. coli bacteria expressing double stranded RNA targeting a larval specific odorant receptor, OR34. RNA interference knockdown of the gene’s transcript was confirmed via qRT-PCR, and chemotaxis assays were used to identify putative odorant ligands to this receptor. This research describes a simple chemotaxis response assay that can be used to identify larval mosquito attractants and an effective way to identify odorant receptors’ potential ligands. Using this information, it should be possible to screen for other ligands that may be used to disrupt mosquito olfaction, and thus develop n

Polycyclic aromatic compounds (PACs) represent a complex and structurally diverse group of aromatic organic contaminants of both petrogenic and pyrogenic origins. These compounds are released into the environment from anthropogenic and natural sources as complex mixtures, encompassing thousands of different aromatic, alkyl-aromatic, and heterocyclic hydrocarbons containing N-, S-, or O- atoms. Overwhelmingly, most of the research in this field has focused on the sixteen 16 US Environmental Protection Agency priority polycyclic aromatic hydrocarbons (PAHs). However, there is still a large knowledge gap on the identification and quantitation of other PACs, for instance halogenated PAHs (HPAHs), which has led to the overarching hypothesis of my thesis: additional PACs are present in the environment and gas chromatography coupled to mass spectrometry can be used to accurately identify and quantify them. The specific class of PACs that I was interested in studying were ones containing halogen atoms. The rationale for this is that the addition of a halogen on the PAC backbone will increase their environmental persistent and bioaccumulative potential relative to non-halogenated species. The first advancement I made was the detection of HPAHs in environmental samples from the Athabasca Oil Sands Region (AOSR). To my knowledge, this is the first report on the detection of HPAHs from AOSR. The second major advancement I made was the validation of two extraction methods for PACs for abiotic (sediment) and biotic (avian egg) samples, respectively. In both studies, I was able to significantly streamline the sample preparation process of PACs. I also compared various quantification methods for PAC analysis which has led to improved measurement accuracy and precision. The overall results of my work will impact future studies on the development of even faster and more cost-effective analytical monitoring techniques, tools designed to delineate sources of crude oil exposures, and fo

Sea ice is a complex medium that covers up to 15 million km^2 of the northern hemisphere annually; presenting a vast highly reflective surface that cools the global climate, providing a variety of habitats for different Arctic species, and both facilitating on-ice travel for local Inuit while also limiting maritime access to Arctic waters. However, anthropogenic warming is amplified by four times in the Arctic which has driven a dramatic reduction in the extent and thickness of the Arctic ice pack and is projected to render the Arctic Ocean seasonally ice-free by the middle of this century. Underlying the loss of sea ice has been a dramatic transformation in the composition of the ice pack from a predominantly multiyear ice (MYI) cover to an inherently thinner and less resilient seasonal ice cover. Historically, the anticyclonic Beaufort Gyre retained sea ice for years, allowing it to thicken while aging, and distributing MYI throughout the Arctic Ocean. However, increasing melt rates in the Beaufort Sea have interrupted the once continuous journey of sea ice through the Beaufort Gyre, cutting off the redistribution and retention of MYI and thereby significantly contributing to the pan-Arctic transition towards a seasonal ice cover. Within this thesis, I use a combination of in situ and remotely sensed observations of sea ice to examine sea ice loss in the Beaufort Sea and its impact on MYI transport and retention within the Beaufort Gyre. In particular, I will examine how the state of the Beaufort Gyre during winter preconditions the regional ice pack for the melt season, and how preconditioning is playing a greater role as the now thinner ice pack is more mobile. I will then use a novel box model to quantify MYI loss in the Beaufort Sea and examine the associated changes in MYI transport through the Beaufort Gyre. Finally, I will set the broader context of MYI loss in the Beaufort Sea by examining MYI loss across the Arctic Ocean and the relative contributions of

Generalist pollinated plants receive pollination services from a wide range of animals, but pollinator effectiveness varies. More effective pollinators in generalist systems optimize pollen transfer by promoting outcrossing between more distant plants. This leads to increased pollinator mediated selection by these pollinators on floral traits and variation in pollinator abundance may therefore cause population genetic and phenotypic differentiation across the range of a species. However, variation may also be caused by plastic responses to variable environmental conditions. Here, I analyze the prevalence and potential causes of interpopulation variation as well as optimal mating distance in generalist pollinated Polemonium brandegeei. I compared morphology and floral scent (1) among four field populations and (2) between field and greenhouse grown plants sourced from the same populations. Populations varied in morphology and floral scent profile and the southernmost population was most distinct with floral traits consistent with increased selection by hawkmoths or hybridization events. All major among population differences were preserved in the greenhouse which suggests a genetic component to phenotypic variation but there was an overall increase in flower size and total scent emission in the greenhouse. Field hand crosses indicated that mating in P. brandegeei was optimized provided crosses were made between plants at least 1 – 3.5m apart, and that environmental variability influenced mating success. These findings may reflect differences in pollinator abundance and/or pollinator mediated selection among populations or hybridization events and offer support for past selection by more effective pollinators (hawkmoths and hummingbirds) which transport pollen over larger distances.

Rising global temperatures associated with climate change have led to various responses and consequences across aquatic ectotherms. At the whole-body level, temperature governs all physiological and biochemical processes, and an increase in temperature is normally positively correlated to the aerobic respiration rate of an organism. However, at a critical sub-lethal temperature (Tcrit), most organisms are unable to supply sufficient oxygen to meet demand of the tissues, leading to a reliance on anaerobic metabolism. At the cellular level, the heat shock response (HSR) is a primary mechanism driving differences in thermal tolerances of ectotherms through the induction of heat shock proteins (HSPs). At a species-specific onset temperature (Ton) when the HSR is activated, there is increased production of HSPs that is positively correlated with temperature but will reach a maximum capacity (Tpeak). Thus, Tpeak for HSP induction can be one metric used to understand thermal tolerance of a given species. Importantly, the HSR is energetically costly as energy demand increases under a thermal stress event, which leads to a further increase in oxygen consumption. This study aimed to examine the effects of increasing temperature on whole-body metabolic rate and mRNA transcript abundance in truncate softshell clam, Mya truncata. We acutely exposed clams from the Northern (Iqaluit, Nunavut) and Southern (Godbout, Quebec) populations to one of six temperature treatments (10, 13, 16, 19, and 22 ℃, and a control group at 7 ℃) for 2 hours and measured whole-body metabolic rate and transcript abundance of key molecular markers of the HSR. Our findings indicated temperature influenced both oxygen consumption and the transcript abundance of thermal stress-related genes. Although there was no statistical significance, a noticeable trend of increasing oxygen consumption with rising temperatures was observed. The impact of temperature on the HSR was clearly reflected in alterations in the

Improving monitoring efforts of Arctic species is becoming increasingly important given the rate of change in Arctic marine ecosystems and the presumed impact on Arctic marine mammals, such as beluga whales (Delphinapterus leucas). Very High Resolution (VHR) satellite imagery is emerging as a promising tool for efficiently monitoring beluga whale populations, which can be logistically challenging with current methods. Here we use VHR satellite imagery to investigate two conservation relevant aspects of beluga whale populations: abundance and social dynamics. First we determined two missing pieces of information required to estimate beluga whale abundance in VHR satellite imagery: 1) depths that beluga whales are visible in VHR satellite images, which are used to define availability bias correction factors, and 2) a comparison of abundance estimates in VHR satellite imagery to current aerial methods. We determined that beluga whales can be detected only at the surface in turbid water and at depths of 0 – 2 m in clear water in 0.31 m resolution VHR imagery, and that beluga whale availability bias corrected abundance estimates made from synchronous VHR satellite imagery and drone surveys were comparable. We further used VHR imagery to describe beluga whale group size, composition, and cohesion in beluga whale populations from Cumberland Sound, Eastern High Arctic – Baffin Bay, and Western Hudson Bay in relation to anthropogenic disturbance, density, and social context. We found that group size decreased with harvest, which seemingly reflects population decline or removal of key social individuals, while recent increases in vessel traffic were associated with larger group sizes and greater spatial cohesion, possibly suggesting an adaptative response to increase vigilance to vessel disturbance. Beluga whale social cohesion was mainly influenced by the presence of juvenile whales, with adult-juvenile mixed groups having smaller inter-individual distances than groups with

Ecological risk assessment (ERA) of contaminated groundwater presents significant limitations due to its often-complex chemical composition and to dynamic processes affecting exposure of organisms in receiving surface waters. The overall aim of this thesis was to better inform ERA of legacy-contaminated sites where groundwater contamination could reach surface water and may impact freshwater organisms. Groundwater mixtures were collected from a pesticide packaging and handling facility in Manitoba, Canada with samples defined as reference zone (RZ), moderate industrial activity zone (MIAZ), and high industrial activity zone (HIAZ) based on historical site activities and chemical characterization of groundwater. Bioassay-driven analyses in combination with molecular assessments were used to characterize the potential ecotoxicological hazard posed by groundwater from a legacy contaminated site to fathead minnow (Pimephales promelas, FHM) as a model organism. To reduce live-animal testing, the potential for molecular assessments in early life stages (ELS) of FHM before independent feeding was evaluated using a novel transcriptomics tool, EcoToxChip, to predict apical responses at higher levels of biological organizations. The potential for laboratory toxicity responses to be predictive of outdoor mesocosms responses was also evaluated. RZ treatments were not toxic to FHMs relative to negative control, and therefore, served as an appropriate site-reference to which effects observed at MIAZ and HIAZ treatments were compared. Overall results revealed that oxidative stress could be the main mechanism of toxicity of contaminants present in MIAZ and HIAZ groundwater mixtures, which included pesticides, hydrocarbons, volatile organic compounds, and degradation products. This toxic mechanism could have led to mortality, deformity, increased swimming activity, and anxiety-like behavior, genotoxicity, hepatotoxicity, and impaired reproductive fitness observed in FHMs in laborato

In this thesis, I explored whether and how environmental clutter affects the process in which an animal searches for a goal. Previous research has suggested that to locate a goal, animals encode specific properties of landmarks. How uninformative objects, or clutter, in the search space impacts this landmark-based goal calculation needs further investigation. I examined this topic using rock pigeons (Columba livia) and pinyon jays (Gymnorhinus cyanocephalus), chosen for their pronounced spatial abilities. I hypothesized that these species would differ in their use of spatial information when learning the location of a goal, and that pigeons would be more affected than pinyon jays by modifications to landmark color and by the appearance or disappearance of environmental clutter. I trained the birds to find a goal using an array of four distinctively colored landmarks. For each species, I assigned birds to one of two groups. Whereas the search space for Group Open contained just the landmarks and the goal, the search space for Group Clutter also contained a set of uninformative objects to simulate environmental clutter. During training, the goal-landmark array rotated and moved across the search space, so that only the landmarks can inform the goal location. Following training, I tested the birds and measured their search error for each experimental manipulation. When learning about the goal location, rock pigeons interpolated the absolute and relative metrics from adjacent landmarks, in both environments. Moreover, pigeons in the cluttered environment used absolute metrics from single landmarks. Pinyon jays exclusively used the absolute metrics from single landmarks in both open and cluttered environments. When the distinctive color information was removed from the landmarks, pigeons but not pinyon jays searched with more error in both environments. For both species, adding clutter to the open environment increased search error, whereas removing clutter from the clut

Candida albicans, the most prevalent human fungal pathogen, demonstrates remarkable adaptability and genome plasticity, enabling it to thrive in diverse environments within the human body. This pathogen unequivocally serves as a common commensal member of the human microbiota and poses as an opportunistic pathogen capable of causing infections under specific conditions. The C. albicans genome can undergo significant alterations, including single nucleotide polymorphisms, insertions, deletions, and chromosomal aneuploidy, particularly under environmental stresses such as exposure to azole drugs like fluconazole. This thesis examines crucial aspects of microbial competition and the evolutionary dynamics of C. albicans under drug stress, particularly fluconazole. Competitive fitness, a fundamental concept in evolutionary biology, measures organisms' ability to survive, reproduce, and compete for resources. Traditional methods for assessing microbial competitive fitness are labour-intensive and involve manual colony counting. Chapter 2 introduces a high-throughput, automated method that employs fluorescent microscopy and machine learning to measure head-to-head competition between microbial populations quantitatively. This innovative approach significantly enhances the accuracy and reproducibility of fitness assessments. Fluconazole is a widely used antifungal agent that has been shown to induce resistance in C. albicans through repeated use. Previous studies on fluconazole tolerance and resistance have largely focused on high population sizes where selection pressure is prominent. This thesis pioneers examining mutation accumulation and evolutionary responses of C. albicans at low population sizes, where genetic drift plays a more substantial role. In Chapter 3, I have evolved replicate lines of C. albicans through mutation accumulation experiments in both the presence and absence of fluconazole, followed by comprehensive phenotypic and genotypic analyses. The results

Lampricide treatments are one of the most common population control methods for invasive larval sea lampreys in the Great Lakes. The success of current population control methods depends on obliterating larval cohorts. However, most testing of the efficacy of different population control methods are carried out on lab-reared larval sea lampreys. In aquaculture, the gut microbiome plays a key role in fitness, including determining how rearing conditions affect the host. This has been studied in many commercially popular fish, but research on the gut microbiome of larval sea lampreys and its role in host growth and development is limited. This is a disadvantage for studies aimed at developing population control methods that depend on lab- reared larvae having a similar physiological response to wild populations of larval sea lampreys. To help breach this research gap, we characterized and compared the gut microbiome of lab- grown (LG), wild-caught lab-reared (WCLR) and wild-caught (WC) larval sea lampreys. Our main findings are that there was a i) strong seasonal pressure driving diversity in the gut microbiome of WC and WCLR larvae; ii) strong influence of the collection site on the gut microbiome of WC larvae; iii) lower diversity of the gut microbiome of LG compared to WC and WCLR samples. Although, we did not detect a core microbiome among our samples, we found common predicted functional pathways among sample types that suggest there could be a microbial functional core. At the genus level, Cetobacterium was the most abundant taxon in WC and WCLR samples. LG samples had unique taxa at higher abundances but shared less abundant taxa with other sample types. Identifying the factors contributing to differences in the microbiome in WCLR or LG samples will inform the development of aquacultural approaches to rearing larval sea lamprey.

Sweat bees in the cosmopolitan genus Lasioglossum are some of the most diverse and commonly collected bees in terrestrial ecosystems. Lasioglossum is made up of several difficult to define subgenera including L. (Hemihalictus) and L. (Sphecodogastra). These two subgenera have never been completely revised in western North America. Taxonomic studies of western Lasioglossum were conducted to clarify subgeneric and species limits. A problematic species complex within L. (Sphecodogastra) was described, which created challenges for subgeneric diagnostics. An improved subgeneric diagnosis was developed for L. (Sphecodogastra) along with a revised key to Lasioglossum subgenera in North America. Then, a review of western Lasioglossum (Hemihalictus) was conducted. The species delimitation process employed an integrated approach, following morphological and geographical data to delineate species boundaries. Morphometric analysis was used for species in the L. (Sphecodogastra) iridescens and L. (Hemihalictus) arizonense groups, using linear discriminant analysis and partitioning around medioids. Three new L. (Sphecodogastra) were described: L. iridescens, L. dilisena, and L. silveirai. Twenty five species of L. (Hemihalictus) were treated, five of which are described as new: L. angustoides sp. nov., L. engleri sp. nov., L. pathiranae sp. nov., L. opata sp. nov., and L. tomentosum sp. nov. Two Palaearctic species are documented in North America: L. villosulum (Kirby) and L. buccale (Pérez). The male of L. subobscurum (Cockerell) is described for the first time. Lasioglossum vanduzeei (Sandhouse & Cockerell) is resurrected from synonymy with L. arizonense. Lasioglossum aspilurum (Cockerell) is considered a senior subjective synonym of Halictus humboldtensis Michener. Six western Nearctic species in the L. nitidiusculum species-group are included in two species complexes: L. ruficorne and L. diatretum species complexes, which likely include unverified synonymies.

The transportation of crude oil across Canada leads to a risk of accidental spills into freshwater environments. Conventional cleanup methods can exacerbate the negative effects of oil spills and delay ecosystem recovery. A less-invasive alternative is the use of engineered floating wetlands (EFWs) – vegetated platforms which promote microbial colonization and biofilm formation in their underwater root-zones – to enhance the biodegradation of spilled oil. This thesis assessed the efficacy of EFWs for removing oil-derived polycyclic aromatic compounds (PACs) from fresh water and the effects of plant species composition and nutrient addition carbon to phosphorus (C:P) ratio on EFW function. Twenty-six (26) ~1550 L mesocosms containing EFWs were exposed to equal-volume spills of water-accommodated fraction (WAF) produced by weathering conventional heavy crude oil (CHV). The EFWs were either planted with a different composition of Typha sp., Carex atherodes, and C. lasiocarpa or had an even species composition and were amended with slow-release fertilizer to achieve a target C:P ratio, based on the carbon content of the WAF. Concentrations of PACs decreased rapidly, with 96.8% of compound classes across the mesocosms declining to baseline concentrations within the first 10 days of the 96-day exposure. There was no evidence to indicate that EFWs had an appreciable effect on PAC removal or that changes in plant species composition or C:P ratio affected EFW function. There were no consistent significant effects of WAF, plant presence, plant species, or C:P ratio on the activity of microbial biofilm or the composition and diversity of the prokaryotic and eukaryotic microbial communities in the root-zone. Results were confounded by low initial PAC concentrations, possibility of PAC sorption to mesocosm plastic, flaws in sample event timing, and tadpole grazing on root biofilm; future research which addresses these experimental limitations is required to support the incorpora

Members of the Ophiostomatales are of economic concern as many are blue-stain fungi including some plant pathogens. The taxonomy of these fungi has been challenging due to the convergent evolution of traits associated with insect dispersal. This project involved comparative sequence analysis of fungal mitochondrial genomes belonging to Ophiostomatales (phylum Ascomycota), which are also rich reservoirs of mobile genetic elements. The work is divided into two chapters. The first chapter is focused on three members of Leptographium sensu lato with inflated mitogenomes owing to abundant introns, including complex intron arrangements. Phylogeny based on mitogenome-derived protein sequences and nuclear markers helped in confirming the separation of Leptographium and Grosmannia species. The second chapter investigates the mitogenomes of nine strains of Ophiostoma ips with a varied global distribution which were sequenced and compared with other members of the Ophiostomatales. A mitogenome intron landscape demonstrated the distribution of the mobile genetic elements and provided insight into the evolutionary dynamics of introns among members of this group of fungi. Examples of complex or nested introns composed of two or three intron modules have been observed in some species, and RNA-Seq analysis suggests possible splicing pathways with regard to resolving complex introns in Ophiostoma ips. Mitochondrial DNA and RNA data for several members of the Ophiostomatales provide the basis for further studies relating to alternative splicing, evolutionary intron dynamics, and taxonomic studies.

Predators are widely recognized for their irreplaceable roles in influencing the abundance and traits of lower trophic levels. Yet, predators also shape community interactions and ecological processes via localized pathways, irrespective of their influence on prey density or behavior. I synthesized empirical and theoretical research and identified pathways by which predators have indirect ecological effects confined to discrete patches. This synthesis revealed how predators indirectly affect other species via patches – ranging from mediating scavenger interactions to influencing parasite/disease transmission risk – and ultimately provides a more holistic view of predation in ecosystems. I then demonstrated how satellite imagery could resolve whether Arctic foxes create biogeochemical hotspots via their denning behavior. Using satellite imagery, I showed that Arctic fox dens have greater plant productivity and green-up faster than reference sites, supporting the hypothesis that Arctic foxes cause the unique vegetation on their dens by concentrating nutrients derived from prey remains there. I then assessed how predators influence the reproductive ecology of Canada geese. Birds presumably select nest sites in areas they perceive are safer, but few links between spatial patterns of risk and nest habitat selection or nesting success exist. By comparing habitat selection models fit to goose nest locations and fox movement locations, I showed predator activity strongly affects the spatial distribution and reproductive success of geese. However, these effects were mediated by the date nest incubation started, revealing how nesting phenology and predator activity interact to shape bird reproduction. Finally, I assessed how fox predation affects goose reproductive success from an ecosystem-level perspective. I showed winter environmental conditions influence the abundance and availability of main winter foods for Arctic foxes, which in turn showed a numerical response to the

Conflict plays a central role in sexual selection by shaping the behaviours and traits that contribute to reproductive success. It drives competition between individuals, influences mate choice and mating strategies, and ultimately shapes the evolution of sexual dimorphism, courtship displays, and other aspects of reproductive behaviour in many species. Informing conservation management strategies aiming at reducing human-wildlife conflicts involves understanding the interplay of genetic, social, and environmental effects on behavioural phenotypic variation. The objectives of this thesis were to investigate the heritable and non-heritable dynamics shaping complex human-polar bear (Ursus maritimus) conflict risk behaviour observed in Churchill, Manitoba. The study aims to understand the influence of climate change and human settlements on population-level behaviour, and understand the individual-level influences of innate, social, and remaining environmental cues driving polar bear conflict risk behaviour expressed by individuals within the Western Hudson Bay subpopulation. These concepts build on the foundations of quantitative genetics and animal behaviour, using data from an extensively monitored wild polar bear subpopulation near Churchill, Manitoba. The findings suggest that conflict risk behaviour is very closely tied to individuals’ ability to survive and reproduce, and that polar bears have a high affinity for environmental learning and for avoiding serious conflicts. Dynamics in conflict risk behaviour over time underscore the influence of environmental stressors, contrasting with minimal cohort effects. Conservation management strategies focused on reducing human-wildlife conflicts should aim to improve the environmental conditions for wildlife by preserving habitat quality and connectivity.