Iron-Regulated Cyanobacterial Predominance And Siderophore Production In Oligotrophic Freshwater Lakes, Ryan J. Sorichetti

Electronic Thesis and Dissertation Repository

The frequency and intensity of cyanobacterial blooms (cyanoblooms) is increasing globally. Contrary to existing phosphorus (P) and nitrogen (N) paradigms describing cyanobloom proliferation in eutrophic (nutrient-rich) freshwater lakes, many of the recent cyanobloom reports pertain to oligotrophic (nutrient-poor) freshwater lakes with no prior history of cyanobloom occurrence. There exists a critical research need to re-visit existing conceptual models, identify regulating factors currently unaccounted for and improve our ability to effectively detect and measure cyanobacterial toxins (cyanotoxins) in lakes. Iron (Fe) is required in nearly all pathways of cyanobacterial macronutrient use, though its direct role in regulating cyanobacterial biomass is not …

Reproductive Biology And Speciation In Drosophila Pseudoobscura, Josh H.M. Alpern

Electronic Thesis and Dissertation Repository

Sexual selection is an important force driving the evolution of reproductive traits, including sperm morphology and mating behaviour. Divergent sexual selection among populations can eventually lead to errors in spermatogenesis in inter-population hybrids, and subsequently speciation. In Chapter 2, I identify a novel sperm class and how its proportion in the ejaculate is adjusted when Drosophila pseudoobscura males are exposed to competition. In Chapter 3, I assess how competition causes both males and females to adjust their mating behaviour. In Chapter 4, I characterize interspecific hybrid spermatogenic breakdown from two closely-related sub-species. While the genetics of hybrid sterility has been …

Soil Freezing Effects On A Grass-Dominated Old Field Ecosystem Under Current And Future Rates Of Atmospheric Nitrogen Deposition, Mat Vankoughnett

Electronic Thesis and Dissertation Repository

Climate change is expected to alter the intensity and dynamics of soil freezing as a result of increased air temperatures and reduced snow cover. Soil freezing can influence ecosystem nitrogen (N) cycling by damaging plants and soil microorganisms, but little is known about how soil freezing effects on ecosystem N cycling may combine or interact with increased atmospheric N deposition, which is also expected to exert a strong influence on terrestrial ecosystems in the coming decades. The objective of my thesis was to examine the combined and possibly the interactive effects of climate induced changes in soil freezing and N …

The Role Of Morphology In Diet And Flower Visitation By Five Species Of Cuban Flower-Visiting Bats, Lindsey Clairmont

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Pollinator and flower morphology are important factors in structuring the plant-pollinator relationship. A pollinator’s morphology may influence aspects of its diet. Flower-visiting bats are an important pollinator group but very little is known about what influences their interactions with food plants. I examined the role of morphology in the partitioning of food resources for five species of flower-visiting Cuban bats. I analyzed cranial traits and body size to examine differences among species and to determine the degree of morphological specialization for flower-feeding for each species. I also collected dietary data from guano and used acoustic monitoring to assess bat activity …

Thermal Adaptation Of Life History Traits In The Drosophila Melanogaster Group, Christopher James Austin

Electronic Thesis and Dissertation Repository

Thermal adaptation is typically detected by examining the tolerance to extreme temperatures in a few populations within a single life stage. However, the extent to which adaptation occurs among many different populations might depend on the tolerance of multiple life stages and the average temperature range that the population experiences. Here, I examined adaptation to local temperature conditions in four species of fruit flies, including a cosmopolitan species, Drosophila melanogaster, and three species with geographically small-sized ranges, D. nepalensis, D. sechellia, and D. mauritiana. The cosmopolitan species showed adaptation to native temperatures during the larval and adult …

Reproductive Behaviour Of Western Bean Cutworm, Striacosta Ablicosta (Lepidoptera: Noctuidae), Females Under Different Abiotic And Biotic Conditions, Joanna K. Konopka

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The Western bean cutworm (WBC) recently expanded its range eastward from the western United States into the Great Lakes region. Little is known about the reproductive biology of this potential pest, therefore I studied the calling behaviour (the emission of the sex pheromone by females) under different biotic (age, mating status) and abiotic (temperature, relative humidity) conditions. Sexual maturation, which occurred several days after emergence, indicating that WBC is a migratory species, was not directly affected by temperature but rather by the difference between day and night temperatures. Calling behaviour was influenced by female age, but not the abiotic factors …

Genetic And Morphological Variation Of Butterflies In Relict Habitats, Lindsay A. Crawford

Electronic Thesis and Dissertation Repository

Habitat fragmentation and loss are leading threats to global biodiversity and can alter patterns of dispersal, population dynamics, and genetics with implications for long-term species persistence. Most habitat fragmentation research has focused on recently fragmented species that historically occupied interconnected habitat patches. We know comparatively little about how naturally fragmented species may respond to habitat loss. For these species, local habitat patch quality may influence the dynamics and genetics of populations more than the structure of the surrounding landscape (e.g., degree of isolation of suitable habitat). I examined aspects of the ecology and evolution of populations inhabiting fragmented landscapes, using …

The Plastic And Evolutionary Responses Of Fish To Anthropogenic Stressors, Ross D. Breckels

Electronic Thesis and Dissertation Repository

Ecosystems are being altered at unprecedented rates with little knowledge of the potential impacts on biodiversity. Two of the most pressing contemporary anthropogenic stressors are pollution and global warming. Species can respond to these stressors via dispersal, phenotypic plasticity, or evolutionary adaptation. Many species, especially aquatic organisms, experience ecological or physical barriers to dispersal and will therefore have to respond via phenotypic plasticity or evolutionary responses. I examined the responses of multiple traits associated with fitness in fish to pollution and increased temperature using a 2 × 2 common garden experimental design. I examined the effects of pollution on behaviour …

The Effects Of Extrinsic And Intrinsic Factors On The Reproductive Biology Of Male Western Bean Cutworm Moths, Striacosta Albicosta (Smith), Jasmine Farhan

Electronic Thesis and Dissertation Repository

Pheromones are important in the mating systems of nocturnal moths as they are relied on to find and/or assess mates. Extrinsic and intrinsic factors have been shown to influence female emission of and male response to pheromones. My thesis focuses on the reproductive biology of males of the western bean cutworm, Striacosta albicosta, a pest of beans and corn that has recently began expanding its range eastwardly. I conducted a field-based experiment to determine the effects of extrinsic factors on pheromone trap catches. I also conducted laboratory based mating experiments to determine the effect of male age on acceptance …

Timing Of Developmental Stress And Phenotypic Plasticity: Effects Of Nutritional Stress At Different Developmental Periods On Physiological And Cognitive-Behavioral Traits In The Zebra Finch (Taeniopygia Guttata), Buddhamas Kriengwatana

Electronic Thesis and Dissertation Repository

Developmentally plastic organisms can respond to stressful environmental conditions by altering multiple aspects of their phenotype, often in a permanent fashion. The timing of developmental stress influences these phenotypic alterations because the prioritization of resources to traits necessary to overcome the stressor may be costly for the development of other traits. Despite the importance of this timing, few studies in birds have accounted for it, and those that have usually examined the effect on a single or few variables. This dissertation addresses the outstanding issues regarding i) the effects of timing of developmental stress on developmental plasticity, and ii) the …

Tree Seedling Establishment In Response To Warming And Nitrogen Addition In A Temperate Old Field, Bryana D. Mcwhirter

Electronic Thesis and Dissertation Repository

Climate change and increased atmospheric nitrogen deposition over the next century may alter the ability of woody species to germinate and compete with grasses and forbs in temperate old fields. To investigate the responses of seed germination and seedling growth to warming and nitrogen addition, I transplanted seeds and seedlings into plots of a field experiment and conducted a greenhouse experiment. The combination of warming and nitrogen allowed seeds to germinate earlier, although there was no effect on final germination. In the greenhouse nitrogen increased seedling growth, and warming had little effect. However, in the field, warming significantly decreased the …

Ecological Constraints And The Evolution Of Cooperative Breeding, David Mcleod

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Cooperative breeding is a social behaviour in which certain individuals will opt to delay or forgo their own reproduction in order to help other individuals. Cooperative breeding is one of the most conspicuous examples of cooperation in nature. However, theoretical understanding of why this behaviour occurs is lacking and contradictory. In this thesis, I examine the role played by ecological constraints on the emergence of cooperative breeding. Contrary to previous results, I find that ecological constraints do matter, provided the population dynamics are properly accounted for. I also examine the long-term evolutionary dynamics of cooperative breeding, and obtain the optimal …

Interactions Among Biotic And Abiotic Controls Of Carbon Dynamics In A Global Change Field Experiment, Eric R D Moise

Electronic Thesis and Dissertation Repository

Climate warming and increased atmospheric nitrogen deposition may substantially influence biosphere C cycling over the next century by altering ecosystem processes such as productivity and decomposition. Field studies are commonly used to explore plant responses to global change, although the underlying mechanisms can be difficult to isolate owing to the lack of control of factors such as plant-animal interactions. Ultimately, indirect effects via herbivore and detritivore responses may feedback to influence plant responses to the experimental treatments. The goal of this thesis was to explore interactions among biotic and abiotic drivers of carbon dynamics within the context of experimental warming …

Measuring Vocal Performance In Song Sparrows (Melospiza Melodia), And Its Relationship To Age, Morphology And Song Complexity., Steven D. Moore

Electronic Thesis and Dissertation Repository

Vocal performance in birds, measured as the ability to rapidly produce broadband trills, has been proposed to reflect male quality. However, little is known about whether performance is consistent across a male’s song repertoire, or whether better performers also have larger repertoires. I quantified vocal performance in 21 male song sparrows (Melospiza melodia). Performance varied among and within males, but was significantly repeatable when considering multiple exemplars of the same trill type within an individual’s repertoire. This suggests that within-individual variation in performance reflects trill types varying in complexity and performance difficulty. Performance was positively and significantly correlated …

Structure Of An Ensemble Of Insectivorous Bats, Matthew A. Emrich

Electronic Thesis and Dissertation Repository

Ensembles of species show distinct characteristics that may permit resource partitioning but few studies focus on more than one or two traits. Using seven sympatric Jamaican bats, I examined features which could allow for spatial, temporal, behavioural and dietary partitioning including wing morphology, echolocation characteristics, flight behaviour, habitat use, and diet. Using acoustic arrays I compared activity patterns at different sites to determine temporal and spatial partitioning and generated flight paths to determine flight speeds. From captured bats I measured wing morphology to examine morphological differences and did genetic analysis of guano to determine dietary partitioning. Morphology, call structure and …

Assessing And Analyzing Bat Activity With Acoustic Monitoring: Challenges And Interpretations, Amanda M. Adams

Electronic Thesis and Dissertation Repository

Acoustic monitoring is a powerful technique for learning about the ecology of bats, but understanding sources of variation in the data collected is important for unbiased interpretation. The objectives of this dissertation were to investigate sources of variation in acoustic monitoring and make recommendations for acoustic survey design and analysis. I addressed this goal in three ways: i) variation resulting from differences in bat detectors, ii) methods for objective identification of peak activity, and iii) the use of stationary transects to address within-site spatial variation.

First, I compared variation of detection of echolocation calls among commonly available bat detectors and …

Overwintering Diet Quality And Timing Of Initiation Of Breeding In The Deer Mouse (Peromyscus Maniculatus), Lindsey Valliant

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Timing of breeding in seasonal environments is important in population dynamics, but it is not always known what cues animals use to time breeding. In northern deer mice (Peromyscus maniculatus) at Kananaskis, Alberta, Canada, early seasonal births are related to overwinter protein supplementation. It is not however known if natural variation in diet quality has the same effect. I hypothesized that yearly winter arthropod availability would influence yearly spring breeding. I predicted that the mean date of initiation of breeding in the population would be related to overwinter diet quality, indicated by ¹⁵N enrichment of hair of …

Small Mammal Foraging And Population Responses To Northern Conifer Mast, Nikhil Lobo

Electronic Thesis and Dissertation Repository

Conifer seeds are a component of the diet of many rodents, and post-dispersal seed predation by rodents is often implicated as a critical constraint on the regeneration of coniferous forests. However, little is known about the effects of conifer seed availability on individual rodents and their populations. The over-arching goal of this dissertation was to investigate the effects and implications of conifer seed production on the foraging and population dynamics of northern small mammals. The predominant conifer study species were white spruce (Picea glauca) and subalpine fir (Abies lasiocarpa), and the main rodents examined were the …