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

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Repurposing historical data to investigate aerial insectivore declines

Date created: 
2019-09-09
Abstract: 

Populations of aerial insectivores have decreased since the mid-1980s, possibly due to declines in their prey. However, long-term data on insect abundance in North America are lacking. I evaluated whether brood size manipulation experiments could be repurposed to assess changes in insect availability. A literature review found no evidence that parents’ ability to respond to a challenge has changed over time, but study methods varied widely. Therefore, I replicated a brood size manipulation experiment conducted on tree swallows in 1994/1995. Parents did not change how they responded to changes in brood size. However, delivery rates were consistently lower in 2017/2018 because parents delivered smaller boluses and tended to visit the nest less. These results are consistent with the hypothesis that aerial insectivores are declining due to reduced insect availability, but could also arise for other reasons. My thesis highlights the value of historical data for investigating aerial insectivore population declines.

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

The evolutionary origins of amphibian extinction risk

Author: 
Date created: 
2019-09-18
Abstract: 

The rise of humanity to ecological dominance has precipitated concerted patterns of environmental change across every biome on Earth. Human activities can upend the adaptive landscapes on which species' have evolved, causing the sudden maladaptation of lineages to these novel conditions. Amphibians are amongst the most threatened vertebrates, with contemporary extinctions driven by multiple interacting stressors including habitat destruction, introduced pathogens, and climate change. Despite these looming threats, we understand little about how or why susceptibility to these stressors varies across amphibian lineages. In this thesis, I investigate the evolutionary origins of modern extinction risk in the Amphibia, by examining comparative patterns of susceptibility to various drivers of extinction. First, I show that modern extinction risk positively covaries with speciation rates across amphibian genera due to the most rapidly-diversifying clades producing numerous range-restricted and vulnerable species. Second, I demonstrate how evolutionary dynamics may influence local-scale extinction by examining amphibian species' responses to deforestation across the world. Contrary to patterns of global threat, the slowest-diversifying amphibian lineages are disproportionately lost from human-modified ecosystems - which may reflect a relationship between diversification and niche lability. Third, I examine phylogenetic and trait-based patterns of susceptibility to a human-dispersed fungal pathogen. Though species' ecology and life history consistently shape infection patterns across diverse amphibian assemblages, these traits appear to bear little weight for species' extinction risk from disease epidemics. Fourth, I test the relative effects of both dehydration and temperature on performance, and therefore climate risk, in three ecologically diverse anuran species. Performance was maintained across broad thresholds of dehydration in all species, but warmer temperatures accelerated the onset of performance decline. Species-specific biophysical modelling revealed stark differences in how dehydration is likely to limit activity in each species, suggesting that desiccation physiology may be an important driver of extinction risk from climate change in amphibians. These studies collectively illustrate that amphibian species' responses to anthropogenic environmental change have deep evolutionary roots. In turn, we can expect our continued environmental dominance to fundamentally reshape the evolutionary tree of amphibians into the future.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Wendy Palen
Arne Mooers
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) Ph.D.

The effect of spawning salmon subsidies on reproduction and territoriality of an avian insectivore

Author: 
Date created: 
2019-02-06
Abstract: 

Resource subsidies link marine, freshwater and terrestrial ecosystems. The movement of marine-derived nutrients from spawning salmon into riparian forests through multiple trophic pathways provides an important subsidy to recipient terrestrial ecosystems. Studies have established links between salmon subsidies and higher densities of indirect consumers, such as insectivorous birds. However, the mechanisms supporting these higher densities remain largely unexamined as studies have focused on patterns rather than processes. This thesis examines the mechanisms and trade-offs supporting higher densities of Pacific wrens (Troglodytes pacificus), a species of avian insectivore, along salmon streams. I found that salmon subsidies mediate habitat selection and reduce territory sizes of adult male wrens along riparian forests. I then examine the effect of salmon subsidies on reproductive success and effort. Thus, not only do salmon subsidies shape spatial occurrence of adult wrens, they also impact breeding behaviour and effort, leading to higher wren reproductive success on salmon streams.

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

The effects of the anti-sea lice chemotherapeutants Salmosan® and Interox® Paramove® 30 on marine zooplankton

Author: 
Date created: 
2020-01-27
Abstract: 

Sea lice infestations can be harmful to both wild and farmed salmon. The Atlantic salmon aquaculture industry relies on the use of chemotherapeutants to control sea lice outbreaks, which can have both economic and ecological impacts. With treatment, several chemotherapeutants are released directly into the water column, potentially exposing non-target organisms. The lethal and sublethal effects of two anti-sea lice chemotherapeutants, Interox® Paramove® 30 and Salmosan®, were examined in wild zooplankton assemblages, wild brachyuran and porcelain crab zoea, and cultured marine copepods (Acartia tonsa). The lowest LC50 values for Interox® Paramove® 30 and Salmosan® of 4 mg/L (CI 4 – 6.9 mg/L) and 54 µg/L (CI 32 – 90 µg/L), respectively) were found for wild zooplankton exposed for 3-h with a 48-h recovery period. The highest Interox® Paramove® 30 LC50 value was 55 mg/L (CI 30 – 95 mg/L) for brachyuran crab zoea using a 1-h exposure, and the highest LC50 value found for Salmosan® was 529 µg/L (CI 333 – 900 µg/L) using a 1-h exposure for wild zooplankton. In terms of sublethal affects, Acartia tonsa naupliar development was more sensitive to both chemicals compared to hatching and reproductive success. After exposure to Interox® Paramove® 30 or Salmosan®, the 3-h naupliar development EC50 values were 0.12 mg/L (CI 0.08 – 0.18 mg/L) and 30 µg/L (CI 20 – 41 mg/L), respectively. The least sensitive Acartia tonsa endpoint tested was immobility after hatching: eggs exposed for 1-h to Interox® Paramove® 30 had an immobility EC50 value of 7.3 mg/L (CI 3.2 – 72 mg/L). In contrast, Salmosan® had no observable effect after a 1-h exposure of Acartia tonsa eggs up to 7500 µg/L. Collectively, these results provide novel toxicity data for two chemotherapeutants to planktonic organisms which will support the safe and appropriate regulation of these aquaculture chemicals in Canada.

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

Effect of diluted bitumen on the survival, physiology, and behaviour of the zebra finch (Taeniopygia guttata)

Author: 
Date created: 
2019-11-27
Abstract: 

Given ongoing and potential increases in shipment of diluted bitumen (dilbit) out of the port of Vancouver, there is a need for toxicity data to assess the impact of catastrophic dilbit spillage on wildlife. Peer reviewed literature on dilbit toxicity is limited to teleost fish, despite the importance of coastal waters as habitat for diverse bird fauna. We used the zebra finch (Taeniopygia guttata) as a tractable, avian model system for preliminary studies on Cold Lake blend dilbit. Objectives were to establish methodology appropriate for determining dilbit toxicity to birds, determine a range of lethal and sublethal doses, and obtain physiological and behavioural endpoints. We conducted three 14-day exposure trials with dosages from 0-12 ml dilbit/kg bw day. Mortality was associated with mass loss, external oiling, elevated OXY, and decreased pectoral muscle mass. In addition, evidence for sub-lethal effects included elevated EROD, increased wet gizzard mass, and behavioural changes.

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

Biology and captive husbandry of Andinobates geminisae, a critically endangered dart frog

Author: 
Date created: 
2019-05-21
Abstract: 

One third of amphibians are threatened with extinction and the number of amphibian captive breeding programs (CBPs) is increasing as components of recovery strategies. However, the success rate of amphibian CBPs is only 50%, and may be limited by health problems resulting from inadequate husbandry knowledge. I investigated the role of husbandry in the occurrence of Spindly Leg Syndrome (SLS), a limb development disease, in a population of captive-bred Andinoabes geminisae tadpoles at the Panama Amphiban Rescue and Conservation Project (PARCP). I found that that vitamin supplementation and filtration method of tadpole rearing water may affect SLS prevalence and that decreasing tadpole husbandry intensity delays the development time of tadpoles. A fortuitous accident during one of my experiments provided compelling evidence that phosphate exposure may also be a key factor in the occurrence of SLS. Accompanying my SLS work, I described the tadpoles of Andinobates geminisae and Oophaga vicentei (Vicente’s dart frog) using tadpoles that died of baseline mortality during my experiments. Combined, my work demonstrates that CBPs can serve beyond their immediate conservation purpose to facilitate important research on the biology of the species they hold.

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

The role of science in wildlife management: From grizzly bears in British Columbia to hunted species across Canada and the United States

Author: 
Date created: 
2017-11-09
Abstract: 

Agencies often claim, and societies often assume, a scientific basis to natural resource management. Science does have potential for informing management, for example by providing rigorous approaches for advancing understanding of managed systems and predicting management outcomes. However, the extent to which science informs real-world management is rarely tested. I offer a simple conceptualization of the management process and show how it identifies multiple focal points for testing the scientific basis of management systems. I illustrate this first with hunt management of grizzly bears (Ursus arctos horribilis) in British Columbia (BC), Canada. I find that the number of kills often exceeds agency-defined sustainable limits, associated with unaddressed uncertainty. I refine approaches from fisheries management to illustrate how uncertainty could be buffered against when setting hunting targets. I then assess the ecology of grizzly bear-human conflict in BC. I find limited support for the common hypotheses that conflict- and hunt-related kills reduce subsequent conflict rates, despite both being management responses. Instead, I find that food availability is correlated with conflict rates, suggesting that more effective management might focus on protecting natural foods. I then focus on protected areas. I use a spatial capture-recapture approach to characterize spatial patterns of grizzly bears in the Great Bear Rainforest and find that existing protected areas do no better, or worse, than random at capturing areas with high densities of grizzly bear activity centres, suggesting protected areas shortcomings. Finally, I explore the process of management itself across Canada and the USA, where hunting is guided by a model which asserts that management is ‘science-based’. However, in 667 management plans from agencies across the continent, I find key hallmarks of science (evidence, measurable objectives, transparency, independent review) largely lacking, raising doubts about a scientific basis. These chapters illustrate how shortcomings at various stages of the management process might undermine the ostensible scientific basis of an overall management system. I argue that assessing the role of science in management is important not only for enabling the evolution of management systems, but also for honest and transparent governance, by clarifying where science begins and ends in decision-making.

Document type: 
Thesis
Senior supervisor: 
John Reynolds
Chris Darimont
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) Ph.D.

Microplastic pollution in the Arctic Ocean: Assessing ingestion and potential health effects in Calanus and Neocalanus copepods

Author: 
Date created: 
2019-08-16
Abstract: 

Microplastics (MPs; plastic particles 1 µm–5 mm) are an emerging contaminant in the world’s oceans; found from surface to seabed in many forms. Evidence for ingestion of MPs exists for a variety of organisms including zooplankton, bivalves, and fishes, raising concern about potential effects in marine food webs. Although studies have reported MPs in the remote Arctic Ocean, data are nonexistent on the ingestion and associated health effects in calanoid copepods (zooplankton). Copepod samples were collected at 56 stations along 10 transect lines spanning the Northeast Pacific and Arctic Oceans and digested according to a novel enzymatic method developed during this thesis. Using light microscopy, MPs were quantified and characterized in Calanus and Neocalanus copepods. Polymer identity was confirmed for each microparticle isolated using Fourier-transform infrared spectroscopy (FTIR). Microplastic ingestion was confirmed at 6 of the 12 Arctic sampling stations. Particle density (PD) ranged from 2.79–15.28 MPs per gram wet weight sample. Differences in PD among survey regions and sampling stations were not significant. RNA:DNA ratios were determined as an indicator of health (i.e., growth and condition) and a station-specific relative RNA:DNA index (RRD) was calculated to account for differences in temperature; both were examined in relation to MP ingestion in Calanus glacialis copepods. A positive trend was observed between station-specific PD and both RNA:DNA ratios and RRD; neither correlation was statistically significant (RNA:DNA ratios: rp = 0.52, p = 0.154; RRD: rp = 0.45, p = 0.220), however the strength of the relationship is notable. The results of this thesis confirm MP ingestion in copepods in the Arctic Ocean, and constitute the first examination of associated health effects in the keystone copepod of Arctic Ocean ecosystems.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Leah Bendell
Peter S. Ross
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.

Pathogen growth inhibition and disease suppression on cucumber and canola plants with ActiveFlower™ (AF), a foliar nutrient spray containing boron

Author: 
Date created: 
2019-07-30
Abstract: 

The effectiveness of ActiveFlower (AF), a fertilizer containing 3% boron in reducing pathogen growth and diseases on cucumber and canola plants was evaluated. In vitro, growth of S. sclerotiorum with AF at 0.1, 0.3 and 0.5 mL/100 mL showed pronounced inhibition at 0.5 mL/100 mL. In greenhouse experiments, the number of powdery mildew colonies on cucumber was significantly reduced by AF at the higher concentrations applied as weekly foliar sprays. On detached canola leaves, AF at 0.5 mL/100 mL and boric acid (BA) at 10 mL/L significantly reduced lesion size of S. sclerotiorum. Phenolic content and boron levels in foliage receiving AF applications were significantly increased. There were no significant differences in lignin. These results indicate that boron present in AF contributed to the disease suppressive effect.

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

Dense core vesicle transport and synaptic capture in neurons

Author: 
Date created: 
2019-08-01
Abstract: 

Dense core vesicles (DCVs) transport signalling molecules, such as brain-derived neurotrophic factor (BDNF), to neuronal synapses utilizing the kinesin KIF1A. BDNF is critical for neuronal function, therefore it is important to understand DCV trafficking and synaptic capture. I used live-cell imaging to characterize DCVs carrying fluorescently tagged BDNF in hippocampal neurons to assess how they translocate to presynaptic sites. Transport was processive both anterogradely and retrogradely and DCVs can be captured regardless of the direction in which they are traveling. Next, I studied whether absence of doublecortin-like kinase 1 (DCLK1), a KIF1A motility modulator, allows for DCV capture at synapses. Using super-resolution microscopy, DCLK1 co-localized only with a small fraction of axonal DCVs. Despite low co-localization of DCLK1 and DCVs, DCLK1 was absent from most synapses (64%). These observations suggest that DCLK1 may not regulate DCV transport in axons but may regulate movement of other KIF1A cargo.

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