Biological Sciences - Theses, Dissertations, and other Required Graduate Degree Essays

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Habitat-specific breeding performance and cavity dynamics of Lewis's Woodpeckers (Melanerpes lewis) in British Columbia

Author: 
Date created: 
2016-06-28
Abstract: 

Lewis’s Woodpeckers (Melanerpes lewis) are Threatened in Canada and rely on pre-existing cavities for nesting. I studied how cavity density, competition, and predators influence Lewis’s Woodpecker breeding performance across three habitats in British Columbia, and investigated the broad-scale patterns of nest tree persistence and reuse over time. I found that Lewis’s Woodpecker breeding performance was high in riparian cottonwood habitat, moderate in live pine, and lowest in crown-burned pine habitat. Cavity density explained habitat-based breeding performance. Nest tree persistence was generally high, but declined over time, and while nest tree reuse varied dramatically across years, there was no consistent temporal pattern. Our results suggest that 1) resource managers should use regionally-specific data for managing Lewis’s Woodpecker populations, and 2) cavities may be a limiting factor for the recovery of Lewis’s Woodpecker populations in Canada, particularly in regions where nest tree persistence is lower and may not support recruitment.

Document type: 
Thesis
File(s): 
Senior supervisor: 
David Green
Nancy Mahony
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.

Contributions to the foraging ecology of house flies, Musca domestica L.

Date created: 
2016-05-26
Abstract: 

Attract-and-kill tactics for control of house flies (Musca domestica) often use foraging cues as attractants. To investigate foraging resources for indoor attraction of house flies, I tested the response of flies to various human foods and a floral resource. In two-choice laboratory bioassays, only dandelion flowers and dandelion honey attracted flies. Analytical attempts to capture the essential semiochemicals from these resources failed, highlighting the need to develop alternative approaches. Another potentially effective foraging cue is the “fly factor”, the phenomenon that food currently or previously fed on by flies attracts more flies than the same type of food kept inaccessible to flies. In two-choice laboratory bioassays, I demonstrate that the fly factor exists in house flies. Of the mechanisms tested potentially causing the fly factor, only fly feces and regurgitate attract flies. Attraction of flies to fly feces and regurgitate indicates that flies sense airborne semiochemicals emanating from these sources.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Gerhard Gries
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.P.M.

The habitat association of bats in the South Okanagan Valley, British Columbia, Canada: Radar-acoustic surveys to assess the use of vineyards by insectivorous bats (Vespertilionidae)

Date created: 
2016-04-15
Abstract: 

British Columbia’s South Okanagan has an expanding wine industry and supports the greatest diversity of bats in Canada. I surveyed bat activity in six matched pairs of vineyards and adjacent natural sagebrush habitats during the summer of 2013 using a unique radar-acoustic system, which I described and evaluated. By evaluating the characteristics of radar tracks and combining radar and acoustic data, I was able to compare bat activity over the habitats. Target parameters (height, speed, and relative size measured as Signal-to-Noise Ratio) had similar distributions in both habitats. There was no statistical difference between habitats in mean target track length per unit area or in the mean number of acoustic ‘individual bat passes’, nor did these measures differ between surveys in early (bat pregnancy and parturition), middle (lactation) and late summer (pup fledging). My results suggest that the amount of bat activity over vineyards and natural habitats is similar; however the use of habitat by bat species differs.

Document type: 
Thesis
Senior supervisor: 
Ronald Ydenberg
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.

Patterns in winter site fidelity and polycyclic aromatic hydrocarbon exposure risk in Barrow’s goldeneye (Bucephala islandica) in the Pacific Northwest

Date created: 
2016-04-08
Abstract: 

Species inhabiting coastal areas can serve as indicators of marine pollution. Hydrocarbons occur naturally in marine ecosystems and wildlife have evolved detoxification systems to manage hydrocarbon exposure. Human activities may increase hydrocarbons in the environment, to the extent that they may be detrimental to biota. Elevated hydrocarbon exposure can be measured directly as increased concentrations in some species, or through biomarkers of active detoxification systems. I found that cytochrome P4501A induction in liver tissue of Barrow’s goldeneyes (Bucephala islandica) and polycyclic aromatic hydrocarbon (PAH) concentration in their winter prey, blue mussels (Mytilus spp.) were correlated across coastal sites in British Columbia, despite generally low PAH concentrations. Using satellite telemetry, I determined that winter movements of Pacific goldeneyes were small, indicating that biomarkers reflected local hydrocarbon levels. These results indicate that the mussel – goldeneye system is useful for evaluating contemporary marine hydrocarbon contamination and recovery endpoints in the event of spills.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Ronald Ydenberg
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.

The Functional Significance of Variation in Hematological Traits that Determine Aerobic Capacity

Date created: 
2016-03-29
Abstract: 

A principal aim of evolutionary physiology is to understand how physiological variation affects the fitness and distribution of organisms. Physiological traits underlie performance, behavior, and life histories and exhibit variation at every taxonomic level. Studies within and between species can reveal whether variation in a physiological trait is currently, and/or was historically, functionally significant. Intraspecific variation is regarded as the raw material on which selection acts, and studying it in relation to measures of fitness can help identify the targets of selection that underlie life history strategies. Comparing interspecific variation with ecological factors can help clarify whether the physiological variation was either shaped by adaptation in response to different selective pressures or influenced differences in habitat and life histories.Traits related to energy expenditure are believed to play a principal role in shaping the evolution of life histories. Hematocrit, the percent of red blood cells per unit volume of blood is a measure of an individual’s oxygen carrying potential and therefore is pivotal in determining endurance. Given that birds show extensive variation in hematocrit within and between species and that flight imposes high energetic costs, variation in hematocrit in birds is likely to be functionally significant. I used observational, experimental, and comparative approaches to investigate the functional significance of intraspecific and interspecific hematocrit variation in birds. Intraspecific hematocrit variation could influence fitness if it plays a role in regulating eggshell colouration or by limiting physical endurance, thereby shaping reproductive decisions. Experimental manipulation of hematocrit in free-living European starlings provided no evidence that hematocrit variation affects eggshell coloration. However, natural and experimental variation in hematocrit influenced fitness measures, suggesting that hematocrit variation, if heritable, is acted upon by natural selection. Comparative analyses indicated that hematocrit variation across passerines was related to habitat altitude, latitude and migration, suggesting adaptive or exaptive significance. Overall, the results suggest that variation in hematocrit within and between avian species is functionally significant. Such studies can help to understand population dynamics, demography, biodiversity, and responses to climate change.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Julian Christians
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) Ph.D.

Inhibition of Caffeine Metabolism in Humans by Furanocoumarin-Containing Plant Extracts: In Vivo and In Vitro Studies

Date created: 
2016-04-25
Abstract: 

Caffeine is found at high concentrations in tea, coffee, soft drinks and energy drinks. Daily consumption of caffeinated beverages is considered to be safe but adverse health effects and deaths have been reported in sensitive or overdosed individuals. A variety of furanocoumarin bioactive has been identified in fruits, spices and herbs from plants in the Apiaceous and Rutaceae families. Since caffeinated beverages are often consumed with food, and both are metabolized by the same CYP1A2 enzyme, we hypothesized metabolic inhibition between caffeine and furanocoumarin-containing food or herbs are common in humans. The goals of this thesis were: (a) to compare the pharmacokinetics of caffeine in humans before and after pre-treatment with a furanocoumarin-containing herb, (b) to elucidate the mechanism(s) of caffeine-herb interaction using in vitro incubations containing pure furanocoumarins and human liver microsomes (HLMs), and (c) to predict in vivo herb-caffeine interactions for humans based on in vitro caffeine metabolism data and in vivo furanocoumarin inhibitor concentrations in the liver.Chapter 1 of this thesis is a brief introduction of caffeine and furanocoumarin-containing food and herbs. In chapter 2, major furanocoumarin bioactives in 29 food and herbs are identified and quantified using gas chromatography mass spectrometry and high performance liquid chromatography. Chapter 3 describes the pharmacokinetics of caffeine in humans after administering 200 mg of caffeine orally before and after pre-treatment with an herbal extract. Caffeine clearance in the volunteers decreased 33.7-77.3% with concomitant increases in area-under-the-concentration-time curve after oral consumption of Ammi majus L., Angelica archangelica L., Angelica pubescens Maxim, Cnidium monnieri (L.) Cusson, or Ruta graveolens L. Chapter 4 provides the experimental evidence for irreversible adduct formation between 14C-labeled 8-methoxypsoralen and HLMs. Moreover, the observed caffeine-herb interaction in humans is best explained by mechanism-based inhibition of CYP1A2 enzyme. Chapter 5 demonstrated the use of in vitro-in vivo drug-drug interaction models and an integrated furanocoumarin dose/concentration to predict in vivo furanocoumarin-caffeine herb interaction in humans. Chapter 6 summarizes the conclusions of this thesis. The experimental and modeling approaches described in this study are also useful in predicting in vivo interactions between prescription drugs and dietary supplements or functional food.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Francis Law
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) Ph.D.

Impact of temperature and relative humidity on the eye-spotted bud moth, Spilonota ocellana (Lepidoptera: Tortricidae): a climate change perspective

Author: 
Date created: 
2016-04-15
Abstract: 

Global climate change models predict an increase in the frequency, severity and duration of extreme weather events. Weather extremes are important for poikilothermic species limited by their capacity to withstand conditions beyond their optimum for survival and development. To understand insect population dynamics, and forecast outbreaks in agro-ecosystems, we need a better understanding of the biology of insect pests of concern. In this study, I explored physiological responses of Spilonota ocellana (Denis & Schiffermüller) in the context of spring frost and summer drought, by focusing on the most vulnerable life stages. I determined that S. ocellana spring larval instars are freeze-avoidant and susceptible to temperatures above their mean supercooling point (SCP) which ranged from -9.1 ± 0.2 °C (4th instar) to -7.9 ± 0.2 °C (6th instar). While supercooling point increased with instar, the median LLT of -7.3 ± 0.4 °C across all instars demonstrates that a hard spring frost would be necessary to cause larval mortality. Exposure to low humidity resulted in lower egg hatch; this effect was exacerbated at higher temperatures. Furthermore, I discovered that exposure to low humidity during the latter half of egg development resulted in reduced survival and faster development rates; these effects were also observed during a period of hot and dry conditions in an apple orchard. This study provides information on the impacts of extreme weather events on survival and development within and between life stages of S. ocellana, which could have the potential to alter population abundance, phenology, and thus management of this pest.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Jennifer Cory
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.

The sublethal effects of Cu exposure on the osmoregulatory and swimming performance in juvenile rainbow trout (Oncorhynchus mykiss)

Date created: 
2016-04-21
Abstract: 

Cu is a widely occurring contaminant in aquatic systems and is acutely toxic to fish. The current paradigm of copper’s toxic mechanism of action in fish is believed to be through direct effects on several important functions of the teleost gill; therefore experiments were conducted to examine Cu effects on the osmoregulatory ability and swimming performance of juvenile rainbow trout (Oncorhynchus mykiss) in water of varying hardness. Fish were exposed to three Cu concentrations (0, 20 and 60 µg/L in hard water [100 mg/L CaCO3], and 0, 6 and 16 µg/L in soft water [6 mg/L CaCO3]), for 4, 8 and 16 d and then tested for their ability to osmoregulate and burst swim. Burst swimming speed (Uburst) was not different between control and Cu-exposed fish in either soft or hard water. Osmoregulatory ability following Cu exposure was examined through several biochemical measurements related to osmoregulation and a seawater challenge. Cu exposure did not elicit a change in any osmoregulatory-related measurement or result in mortalities during the seawater challenge. These results indicate that the current paradigm of Cu toxicity may not reflect the mechanism of sublethal Cu toxicity or that compensatory mechanisms are offsetting major physiological disturbances caused by Cu, at concentrations that are near those which typically cause mortality in salmonids.

Document type: 
Graduating extended essay / Research project
File(s): 
Senior supervisor: 
Chris Kennedy
Department: 
Science: Biological Sciences Department
Thesis type: 
(Project) M.E.T.

Contributions to the development of effective food baits and pheromone lures for capturing mice and rats

Date created: 
2016-04-21
Abstract: 

My research aimed to improve trap captures of mice and rats by incorporating food cues and pheromone signals into a bait complex. I show that a food bait consisting of cereals, fructose, soy lecithin and a semiochemical blend in safflower oil, suspended in a gelatine/water solution, mediates feeding by mice and rats in the laboratory and capture of wild mice in the field. Traps baited with bedding soiled by caged male mice attracted juvenile and adult female mice, indicating the presence of a sex pheromone in soiled bedding. Analyses of male and female bedding odorants by gas chromatography-mass spectrometry show that the known primer pheromone components 3,4-dehydro-exo-brevicomin (DEB) and 2-sec-butyl-4,5-dihydrothiazole (DHT) were present in male bedding. In a field experiment, traps baited with DEB and DHT captured four times more female mice than corresponding control traps, indicating that DEB and DHT are sex attractant pheromone components of male house mice.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Gerhard Gries
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.P.M.

Habitat-mediated predation and selective consumption of spawning salmon by bears

Date created: 
2016-04-15
Abstract: 

Predator–prey interactions are key elements of ecosystem functioning and can be mediated by physical characteristics of the environment. To examine this, I studied interactions between bears and spawning salmon on the Central Coast of British Columbia, Canada. I first show how size-biased predation is mediated by stream characteristics that provide refuge for prey, with implications for size-selective pressures acting on salmon in different streams. I then demonstrate that bears feed selectively on energy-rich parts of salmon, depending on characteristics of the stream, with consequences for terrestrial nutrient transfer via uneaten salmon biomass. Overall, I found that bears captured larger salmon in streams with less wood and fewer undercut banks and fed more selectively in narrower, shallower streams with less pool volume. This suggests that habitat characteristics play a role in mediating predator behaviour and, therefore, have implications for the selective pressures faced by salmon, and nutrient subsidies to surrounding habitats.

Document type: 
Thesis
File(s): 
Senior supervisor: 
John Reynolds
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.