Ecology and Evolutionary Biology Commons^™

Top-Down And Bottom-Up Effects On Collembola Communities In Soil Food Webs, Jordan Kustec

Electronic Thesis and Dissertation Repository

Anthropogenic changes are causing shifts within soil food web communities, which may alter ecosystem processes such as nutrient cycling, carbon storage and decomposition. I quantified ecological stressor effects on the abundance, richness, community composition and body size of a soil-dwelling microarthropod (Collembola: Hexapoda). I quantified the effects of warming and nitrogen deposition in two separate field studies and demonstrated that warming shifts Collembola community structure and decreases community body size. I quantified the interactive effects of top-down and bottom-up forces mediated by warming as ecological stressors in Collembola communities. I found that bottom-up effects of nutrient addition did not affect …

Landscape-Level Effects Of Agricultural Intensification On The Condition And Diet Of Nestling Barn Swallows (Hirundo Rustica), Jackson W. Kusack

Electronic Thesis and Dissertation Repository

Farmland bird populations have experienced declines with increasing agricultural intensification for which the leading hypothesis is a reduction of prey insects. This may be especially relevant for aerial insectivores whose primary diet is aerial insects. For this thesis, I examined nestling body condition and used stable isotopes (δ¹³C, δ¹⁵N) and fecal DNA barcoding to determine the diet of a farmland breeding aerial insectivore, the Barn Swallow (Hirundo rustica), within an agro-ecosystem in Southern Ontario, Canada. Nestling body condition was positively affected by agricultural intensification, but all benefits were lost by the pre-fledging stage and …

Hitchhiker's Guide To Migration: Effects Of Experimental Parasitic Infection And Other Immune Challenges On Migratory Traits Of Sparrows, Tosha R. Kelly

Electronic Thesis and Dissertation Repository

Seasonal migration exposes animals to a variety of habitats and parasites, and if infected migratory birds migrate successfully there is great potential for birds to transport infectious diseases long distances. Our current understanding of whether birds contribute to the spread of disease relies upon observational field studies that are limited in their ability to discern cause from effect. Using captive and field-based experiments for my doctoral research, I answered three research questions: (1) are nocturnal migratory restlessness (Zugunruhe) and body condition affected by mounting an acute phase immune response during migration; (2) what are the impacts of parasitic …

Spatial And Temporal Patterns Of Neutral And Adaptive Genetic Variation In The Alpine Butterfly, Parnassius Smintheus, Maryam Jangjoo

Electronic Thesis and Dissertation Repository

Understanding how much genetic diversity exists in populations, and the processes that maintain that diversity, has been a central focus of population genetics. The evolutionary processes that determine patterns of genetic diversity depend on underlying ecological processes such as dispersal and changes in population size. In this thesis, I examine the influence of dispersal and population dynamics on neutral and adaptive genetic variation in a naturally occurring network of populations of the alpine butterfly, Parnassius smintheus.

My first objective was to determine the combined consequences of demographic bottlenecks and dispersal on neutral genetic variation within and among populations. Using …

Patterns And Drivers Of Stream Benthic Macroinvertebrate Community Taxonomy And Function In Agroecosystems, Edward M. Krynak

Electronic Thesis and Dissertation Repository

Anthropogenic activities continue to expand and intensify resulting in vast areas of the globe being dominated by human land uses. Effective land management and conservation decisions depend on our ability to understand and predict biological response to further disturbance in already stressed ecosystems. Moreover, insight into biological response to ecological stressors may be advanced by using trait and functional community measures in combination with taxonomy. My dissertation goal was to describe patterns and drivers of variation in benthic macroinvertebrate communities (BMIC) taxonomic composition and function in streams in an agriculturally dominated landscape. I achieved my goal by conducting three related …

The Post-Fledging Survival And Movements Of Juvenile Barn Swallows (Hirundo Rustica): An Automated Telemetry Approach, Dean R. Evans

Electronic Thesis and Dissertation Repository

For migratory songbirds, population dynamics are primarily influenced by juvenile or first year survival, but survival between fledging and fall migration is particularly important. Unfortunately, our knowledge of this post-fledging period is largely limited due to the difficulty of tracking juveniles outside the nest. For this thesis, I used automated radio telemetry to track the survival and post-fledging movements of 216 juvenile Barn Swallows (Hirundo rustica) from fledging up until departure for autumn migration in 2016-2017. Average apparent survival was 42% for both broods and nestlings in better body condition had higher survival. Nestlings from second broods migrated …

Hierarchical Variation In Cellulose Decomposition Across Southern Ontario Reference Streams, Jenna R. Webb

Electronic Thesis and Dissertation Repository

The cotton strip assay (CSA) has been promoted as a method of incorporating functional indicators into standardized river assessments by study of organic-matter decomposition. However, operationalization of the CSA as an indicator requires testing the spatial and temporal controls of variance associated with decomposition of cotton strips at regional reference sites. I conducted a hierarchically structured study of decomposition rates in Ontario, Canada. Cotton strips were deployed during the spring, summer and fall in pool and riffle habitats of 22 streams located in three distinct physiographic regions. Partitioning of variation among hierarchical scales associated with rates of decomposition were examined …

The Effect Of Shelter Availability On Foraging In Atlantic Salmon (Salmo Salar), Christian A. Therrien

Electronic Thesis and Dissertation Repository

Shelter is an environmental feature that provides protection from danger and its use is an important anti-predator behavior for juvenile Atlantic salmon (Salmo salar). However, how shelter availability influences the foraging of these fish in the wild is not well documented. I predicted that juvenile Atlantic salmon would alter their foraging behavior in a low shelter environment and that this effect would differ between individuals from two populations that are targeted for reintroduction into Lake Ontario. I measured the foraging activity of juvenile Atlantic salmon from the two populations while they were held in pens in a Lake …

The Costs Of Fear: Integrating Fear Effects On Prey Into Population Ecology, Marek Charles Allen

Electronic Thesis and Dissertation Repository

Predators not only kill prey, but through the 'fear' of predation, predators induce costly anti-predatory responses in prey. Anti-predatory costs may scale up to effects on prey populations, through effects on prey reproduction and survival. This thesis aimed to quantify the net effect of predation risk effects on a prey population in a terrestrial vertebrate system for the first time. I manipulated the perceived risk of predation in multiple study years by exposing song sparrows (Melospiza melodia) to playbacks of either predator or non-predator calls. Females exposed to predator playbacks laid fewer eggs, had more eggs fail to …

Plant Stimuli-Responsive Biodegradable Polymers For The Use In Timed Release Fertilizer Coatings, Spencer Heuchan

Electronic Thesis and Dissertation Repository

The use of nitrogen-based fertilizers continues to accelerate with human population growth and increases in global food requirements. Enhanced efficiency fertilizers (EEFs) have been developed to improve the synchronization between nutrient supply and crop nutrient demand. However, many of the current controlled release fertilizers are coated with non-degradable polymers that contribute to accumulation of microplastics within ecosystems. This thesis describes research towards the development of a new class of fertilizer coatings using a self-immolative polymer known as poly (ethyl glyoxylate) (PEtG). PEtG itself does not have suitable properties to produce a viable coating but once blended with another degradable polyester …

Creating Tools To Determine Whether Katanin 60 Affects Female Rejection Of Males In Drosophila, Joshua R. Isaacson

Electronic Thesis and Dissertation Repository

During courtship, it is vital for organisms to recognize conspecifics because of the costs associated with forming interspecies hybrids. Many organisms use species-specific cues to recognize potential mates. These cues are perceived and evaluated via neural pathways. The genetic basis of how species-specific cues are evaluated and processed into receptive or rejection behaviour remains almost entirely unknown. The gene Katanin 60 (Kat60) has previously been identified as contributing to interspecific mate rejection between Drosophila melanogaster and D. simulans. I use the CRISPR/Cas9 system and RNA interference (RNAi) to confirm if Kat60 influences female receptivity between D. melanogaster …

Atmospheric Change Promotes Increasing Cyanobacteria Dominance In Swedish Lakes, Erika Christiane Freeman

Electronic Thesis and Dissertation Repository

The frequency and intensity of cyanobacteria blooms are increasing globally. The interacting effects of environmental drivers, including increased temperature, altered precipitation, reduced acidification-with associated shifts in nutrient limitation- and increased dissolved organic matter loads to lakes are predicted to create favourable environmental conditions for cyanobacteria in northern lakes. This prediction was tested in 28 nutrient-poor Swedish lakes over 16 years (1998-2013). Increases in cyanobacteria abundance were identified in 21% of the study sites, composed mostly of increases in three specific genera: Merismopedia, Chroococcus, and Dolichospermum. Increases in temperature favoured Merismopedia dominance in lakes with low pH and high nitrogen to …

Models Of Conflict And Voluntary Cooperation Between Individuals In Non-Egalitarian Social Groups, Cody Koykka

Electronic Thesis and Dissertation Repository

This thesis broadly investigates the evolution of voluntary cooperative behaviour among individuals in conflict in non-egalitarian social groups. This work is partitioned into three sections. In the first section, we explore the emergence of non-egalitarian social groups to better understand the evolutionary incentives for voluntary participation in groups with unequal distributions of resources. In the second section, we study several scenarios in which genetically related individuals with unequal control over resources cooperate despite being in conflict. The evolution of parent-offspring conflict over provisioning, offspring signals, and alloparental care are each addressed in this section. In the last section, we investigate …

Differential Spring Migration In The White-Throated Sparrow (Zonotrichia Albicollis), Andrew T. Beauchamp

Electronic Thesis and Dissertation Repository

Differential migration timing between distinct classes of individuals is commonly observed in songbirds, however, the underlying behavioural mechanisms of differential timing are still uncertain for most species. My research applied a suite of advanced techniques to examine differential migration timing (by sex and morph) and its underlying behavioural mechanisms (refuelling rate, stopover duration, and wintering latitude) in spring migrating White-throated Sparrows (Zonotrichia albicollis) at a key stopover site. Protandry was the only form of differential migration timing observed, with males arriving at stopover on average 11 days earlier than females. Males and females had similar refuelling rate, stopover …

Trophic And Competitive Interactions Among Egg Parasitoids Of Stink Bugs, Joanna K. Konopka

Electronic Thesis and Dissertation Repository

The intra- and inter-trophic interactions in ecosystems can be disrupted by invasive species, with lasting effects on population dynamics of native organisms. An invasive species may be attractive as a prey or host to native species, but if unsuitable for consumption or for development of the natural enemy’s progeny, it constitutes an ‘evolutionary trap’. A possibility of such a trap for native egg parasitoids (Hymenoptera: Scelionidae) exists with the introduction of the exotic brown marmorated stink bug, Halyomorpha halys (Hemiptera: Pentatomidae). The objective of this thesis is to enhance the understanding of Pentatomidae-Scelionidae host-parasitoid interactions from a behavioural ecology perspective, …

Soil Homogenization: Plant Species Diversity, Ecosystem Properties And Soil Freezing Effects During Tallgrass Prairie Restoration, Holly J. Stover

Electronic Thesis and Dissertation Repository

Tillage can increase soil uniformity in former agricultural sites. Within plant communities, niche-based species sorting may occur among distinct soil patches (microsites), increasing diversity, and the interfaces between microsites (microedges) also may provide unique microsites. However, the influence of soil homogenization and microedges on ecosystem processes and plant responses to stress have not been examined. My thesis assessed if adding microsites containing sand, woodchips, pits or mounds increased plant species diversity, productivity, decomposition and nitrogen retention (¹⁵N tracer) and buffered plant responses to soil freezing in a tallgrass prairie restoration on former cropland. Homogenization decreased diversity in flat …

Wildlife In A Premier African Protected Area Do Not Perceive Ecotourists As Predators, Badru Mugerwa

Electronic Thesis and Dissertation Repository

Researchers have reported that the presence of ecotourists may displace or disturb wildlife with potentially adverse effects, and may be a more serious problem if wildlife perceive ecotourists as predators. I used a playback experiment to test if wildlife at Bwindi Impenetrable National Park, Uganda, perceive ecotourists as predators. I contrasted wildlife behavioural responses to vocalizations that simulate those of ecotourists to those of local predators (positive controls; dogs and the extirpated native apex predator, leopard) and a non-predator (negative control; insects). Using responses from 14 mammal species, I show that wildlife do not perceive ecotourists as predators, responding no …

The Major Histocompatibility Complex In Song Sparrows: Immunity, Signals, And Mate Choice, Joel W.G. Slade

Electronic Thesis and Dissertation Repository

In recent years, sexual selection theory has redefined genetic quality to consider not only additive genetic effects on fitness but also non-additive genetic effects, such as heterozygote advantage or disadvantage. In jawed vertebrates, the major histocompatibility complex (MHC) gene family has been shown to exhibit both additive and non-additive genetic effects on fitness. MHC gene products are involved in initiating adaptive immune responses, and MHC genotype determines the range of pathogens to which an individual can respond. Therefore, parasite-mediated selection at MHC may favour locally-adapted, rare, or particular combination of alleles. Because heterozygote advantage at MHC is widespread, sexual selection …

Maternal Effects And The Evolution Of Chinook Salmon, Michael Thorn

Electronic Thesis and Dissertation Repository

Pacific salmon (Oncorhynchus spp.) populations are under increasing threat due to habitat degradation, over fishing, invasive pathogens, and climate change. The early life history stage (fertilization – free feeding) is one of the most vulnerable developmental phases and performance at this stage may be a critical factor affecting population persistence. Offspring traits and performance are often greatly influenced by maternal effects, which have the potential to alter patterns of inheritance and selection, and environmental factors such as temperature. However, the contribution of maternal effects to the evolution of offspring traits under varying environmental conditions is still poorly understood in …