Western University BiologyWestern Science

Archived Friday Philosophicals Abstracts - Fall Semester 2013

December 6, 2013

Heather MacGillivray: The effect of natal philopatry on parasite load and immune function in song sparrows (Melospiza melodia)

Friday Philosophicals - December 6Supervisor: Dr. Beth MacDougall-Shackleton
Degree: M.Sc. Candidate

Parasites are a widespread and diverse group that can significantly impact host survivorship and reproductive success. The more heterogeneous the environment an organism encounters, the more likely it is to encounter a wider variety of parasites; if a bird moves to a new population, it must cope with infection by new and foreign parasites. Previously in my studied song sparrow population, birds of local natal origin were found to have lower parasite loads than non-local birds. Local adaptation and coevolution have been suggested as mechanisms explaining this, but I examine an alternative: varied immunocompetence.  I use assignment tests to determine whether birds of this population are of local natal origin and I relate this to parasite loads and to several measures of immune function.

Mathis Natvik: Mechanisms of Oak Recruitment Failure in Old Fields: The Role of Non-Indigenous Grasses

Friday Philosophicals - December 6Supervisor: Dr. Hugh Henry
Degree: M.Sc. Candidate

Oaks were historically dominant canopy trees in many North American ecosystems. Failure to sufficiently regenerate over the past century has left most oak populations in steep decline. This phenomenon is known as “oak recruitment failure”. The Quercus genus is a larval host to 534 Lepidoptera species, more than any genus on this continent. The insect biomass produced on oaks is critical food for many songbirds. I will be studying the mechanisms by which non-indigenous creeping red fescue (Festuca rubra var. commutata) limits oak recruitment in old field ecosystems. These mechanisms are still unclear and proposed factors include herbivore overpopulation, competition, and missing ectomychorrhizal associations. My research will specifically test if creeping red fescue releases allelopathic phytochemicals that suppress acorn germination and subsequent seedling survival.

November 29, 2013

Tosha Kelly: Stable isotope analysis of migratory distance and its relationship to immune allocation in song sparrows Melospiza melodia

Friday Philosophicals - November 29Supervisors: Dr. Beth MacDougall-Shackleton and Dr. Scott MacDougall-Shackleton
Degree: M.Sc. Candidate

Life-history theory predicts animals face trade-offs with immune defence while performing strenuous exercise, such as migratory flight. Long and short-distance migrants differ in the parasites they encounter where short distance-migrants re-encounter the same pathogens throughout their lifetime while long-distance migrants encounter a much larger set of parasite fauna. I hypothesize that song sparrows of a partially migrant population should strategically allocate immune function in relation to their migratory strategy and, thus, parasite fauna. Using stable isotope analysis and a variety of immune techniques my results show that, overall, long distance migrants had weaker immune responses than short-distance migrants. Additionally, upon arrival to breeding grounds birds shifted their immunity from innate to adaptive. This demonstrates the high energetic cost of migration and plasticity of immune allocation.

Kimberly Schmidt: Song as an Honest Indicator of Developmental Stress in Song Sparrows

Friday Philosophicals - November 29Supervisor: Dr. Scott MacDougall-Shackleton
Degree: Ph.D. Candidate

Birdsong is a sexually selected trait that influences female mating preferences and male-male competition. Features of male song production correlate to measures of male condition and fitness suggesting that song is an honest indicator of male quality. One problem with this theory is that it has been difficult to determine the costs associated with certain song attributes, such as song complexity. The Developmental Stress Hypothesis proposes that the honesty of birdsong is maintained by costs incurred during development, such that song in adulthood reflects exposure to early-life stressors. I provide support for this hypothesis by showing that exposure to early-life stress affects: 1) adult phenotypic quality, 2) adult male song production, and 3) development of a brain region involved in song learning and production.

November 22, 2013

Asma Asemaninejad: Global change impacts on communities of fungi in boreal peatlands

Friday Philosophicals - November 22Supervisor: Dr. Greg Thorn
Degree: Ph.D. Candidate

Peatlands have an important role in global climate change through sequestration of atmospheric CO2, but there is concern that altered fungal community function may turn peatlands from carbon sinks to carbon sources, greatly exacerbating the impacts of climate change. In an experiment established in Western's Biotron facility, I will assess the impacts of the elevated temperature, carbon dioxide concentration and altered hydrology associated with Canada's predicted climate change on communities of fungi in intact peat cores. Community genomic DNA will be extracted from peat samples from cores in each experimental treatment and fungal communities will be assessed by next-generation sequencing of a portion of ribosomal DNA.  Changes in fungal communities will be related to changes in nutrient cycling and release, vegetation, and peat microfauna.

Aleksey Paltsev: Predicting susceptibility of oligotrophic lakes in Ontario to formation of cyanobacteria blooms

Friday Philosophicals - November 22Supervisor: Dr. Irena Creed
Degree: M.Sc. Candidate

Lakes in North America have experienced an increase in the frequency of cyanobacterial blooms over the last 15 years. While cyanoblooms were the bane of water quality issues in the 1970’s, restrictions in the release of phosphate into surface waters virtually eliminated them. In my project I consider a new model aimed at explaining why some lakes in Ontario experience new cyanoblooms, in spite of phosphate release restrictions. I hypothesize that the reasons for this are climate-driven changes in lake’s contributing catchments that cause alterations in nutrient discharge. I evaluate the effect of the nutrient contribution to the phytoplankton biomass and the cyanobacterial presence, normalizing the lakes for their shapes and sizes using digital bathymetry data. This is the first study to compare the importance of catchment controls on nutrient dynamics in lakes coupled to the effect of lake morphometry on increasing risk of cyanoblooms.

November 15, 2013

John Loggie: Androgen and immunity tradeoffs in Bluegill Sunfish (Lepomis macrochirus)

Friday Philosophicals - November 15Supervisor: Dr. Bryan Neff
Degree: M.Sc. Candidate

The immunocompetence handicap hypothesis posits that androgens such as testosterone and 11-ketotestosterone have an immunosuppressive effect. This enables androgens and their associated behaviors to function as honest signals of fitness, as only males with the best genes for immune defense can afford the immunosuppression caused by these hormones. Alternate male life histories have been documented in Bluegill Sunfish (Lepomis macrochirus). Parental males have high androgen levels, and must use aggressive behaviours to defend their nests from intruders. Sneaker and satellite males have low androgen levels and steal fertilization events from parental males. The life histories are thus expected to differ in their response to an experimental immune system challenge, due to differing levels of androgen production. Understanding how reproductive hormones affect immunity is critical, as concentrations of endocrine disrupting compounds continue to increase in aquatic environments worldwide.

Tara Crewe: Assessing the use of counts of migrating individuals for population monitoring

Friday Philosophicals - November 15Supervisor: Dr. Phil Taylor
Co-supervisor: Dr. Christopher Guglielmo
Degree: Ph.D. Candidate

Counts of migrating animals are often used for long-term population monitoring and for the assessment of Species At Risk.  However, the use migration counts for this purpose relies on several assumptions, including that individuals counted depart the count site within 24 hours; that factors that influence counts, including effort, habitat, and stopover duration, do not vary systematically over time; and that detected fluctuations in population size are proportional to fluctuations in the underlying larger-scale populations. Using simulated counts of migrating birds, I examine how sampling intensity and stopover duration influence our ability to reliably estimate population change.  I also assess whether regional and national population trends can be detected with sufficient power to inform conservation efforts, given realistic levels of daily and annual variability in counts at and among migration count sites.

November 8, 2013

Muna Basahi: The effect of treatments of potato seed tubers with Pseudomonas strains on the number of pathogenic Streptomyces on the mother and daughter tubers

Friday Philosophicals - November 8Supervisor: Dr. George Lazarovits
Co-supervisor: Dr. Greg Thorn
Degree: M.Sc. Candidate

Potato common scab is a tuber- or soil-borne disease caused by several species of Streptomyces. Once established in the soil these bacteria can survive for years making it difficult to eradicate. However, recent studies showed that suppressiveness against common scab can develop naturally due to the presence of antagonistic micro-organisms such as Pseudomonas species. The objective of this study is to reduce or eliminate the number of pathogenic Streptomyces found on the potato surface to reduce or eliminate transmission of common scab to non-infested soils. Preliminary results showed statistically significant decline in the number of pathogenic Streptomyces per gram of tissue on the mother tuber. In the field trial, seed treatments showed statistically significant differences in yield but not in scab incidence between different cultivars.

Katelyn Weaver: Agricultural and Aquatic Habitat Selection by Eastern Population Tundra Swans, Cygnus columbianus columbianus, during the Nonbreeding Period

Friday Philosophicals - November 8Supervisor: Dr. Scott Petrie
Co-supervisor: Dr. Hugh Henry

Waterfowl exploitation of agricultural forage has triggered population increases and changes in migration routes and timing of migration. Because changes in habitat availability and foraging profitability have the potential to greatly influence the population dynamics of waterfowl, understanding temporal and geographic selection of these habitats is necessary to manage resource availability for waterfowl. The purpose of my research was to identify these selection relationships and to further understand the mechanisms driving them. Results indicate wetlands were used equal to availability during migration, but were not selected during winter when Tundra Swans selected open water and agricultural habitats. Open water was the most strongly selected habitat during migration and seasonal comparison of migration indicated a 2-fold increase in use of agriculture from autumn to spring. My results have contributed to scientific understanding of avian migration and wintering ecology and will help guide management of Arctic-nesting waterfowl throughout the nonbreeding period.

October 25, 2013

Taylor Finger: Factors influencing spring migration chronology of Lesser Scaup (Aythya affinis) and Mallards (Anas platyrhynchos)

Friday Philosophicals - October 25Supervisor: Dr. Scott Petrie
Co-supervisor: Dr. Irena Creed
Degree: M.Sc. Candidate

Weather affects timing of spring migration in birds but how exogenous factors influence timing and rate of migration by lesser scaup to their breeding grounds is relatively unknown.  I used locations of scaup tracked by satellite telemetry, waterfowl surveys of scaup and mallards, and corresponding weather data to evaluate competing models to explain variation in timing and rate of migration by scaup.  Timing of spring migration varied negatively with factors influencing energetic costs (spring mean temperature) and positively with those affecting habitat availability (rainfall and snow water equivalence). Difference in date of peak migration by scaup and mallards through North Dakota was not explained by exogenous factors.  My analyses suggest flexibility in timing and rate of spring migration by lesser scaup based on exogenous factors.

Toby Thorn: The Use of Great Lakes Islands by Migrating Bats

Friday Philosophicals - October 25Supervisor: Dr. Brock Fenton
Co-supervisor: Dr. Jeremy McNeil
Degree: M.Sc. Candidate

Flight allows bats to migrate over relatively large distances, in order to follow food resources and favorable weather climate. Large numbers of North American migrate through the region of the Great Lakes, which can provide a significant physical barrier. I am investigating the importance of two Great Lake islands, Amherst and Pelee. I am collecting data using acoustic data from remote bat detectors, and will analyse this to identify species, look for annual patterns in activity, and compare to activity at other sites. If the islands prove to be significant sites for migrating bats, this could make them a priority for conservation, as degradation at such sites could have a disproportionate effect of the wider population.

October 18, 2013

Paul George: Response of soil nematodes to wood ash amendment in forest soils following tree harvest

Friday Philosophicals - October 18Supervisor: Dr. Zoë Lindo
Degree: M.Sc. Candidate

The use of wood ash as a soil amendment is a popular practice in Scandinavian silviculture but still being assessed in Canada. Effects of wood ash on soil communities are not fully understood including its effects on soil animal communities. Nematodes are ubiquitous in soils, representing a major link in soil energy pathways between microflora and larger animals. This project investigates the effects of wood ash on free-living nematode communities in a forestry stand near Chapleau, Ontario. Traditional measures of community composition (richness, abundance), as well as the nematode-specific Maturity Index will be compared to a novel application of Body Size Spectra – a measure of community composition based on organism size instead of identity. This project is a first-step in the assessment of wood ash effects on nematode communities in Canada and demonstrates the potential for Body Size Spectra as a standard soil community measure.

October 11, 2013

John O'Leary: Population genetic structure in the flesh fly, Fletcherimyia fletcheri, a commensal inhabitant of the northern purple pitcher plant, Sarracenia purpurea.

Friday Philosophicals - October 11Supervisor: Dr. Nusha Keyghobadi
Degree: M.Sc. Candidate

Communities and populations that occupy container-like habitats, such as the northern purple pitcher plant, Sarracenia purpurea, are ideal for addressing questions in spatial ecology and landscape genetics due to the occurrence of multiple species within spatially well defined habitat patches. The northern purple pitcher plant is the exclusive larval habitat for the flesh fly, Fletcherimyia fletcheri. I examined the effects of broad scale landscape configuration and composition on the population genetic structure of this flesh fly in 15 discrete habitat patches across Algonquin Provincial Park. Through the use of spatially referenced genetic samples I developed a model to test hypotheses about rates of gene flow and movement through the landscape, based on least cost pathway analysis.

September 27, 2013

Lindsey Clairmont: The Role of Morphology in Diet and Flower Visitation by Five Species of Cuban Flower Visiting Bats

Friday Philosophical - September 27Supervisor: Dr. Brock Fenton
Degree: M.Sc. Biology

Flower-visiting bats are an important pollinator group but 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 collected dietary data from guano and used acoustic monitoring to assess bat activity at flowers. I found evidence of partitioning of plant resources among the bat species, although evidence of limiting resources was not observed. Morphological similarity between species did not predict dietary overlap. However, species differing in their morphological specialization for nectarivory consumed resources and visited flowers at different frequencies.

Steve Sharron: Fish out of Saltwater: Rapid Adaptation of Smoltification Traits in Pacific Salmon

Friday Philosophicals - September 27Supervisor: Dr. Yolanda Morbey
Degree: M.Sc. Candidate

Salmonid fishes are excellent systems for studying the phenomenon of rapid adaptation following introduction into novel environments. The Great Lakes have been stocked with Pacific salmon for a century and many naturalized populations have established. These populations present an opportunity to investigate adaptations of preparatory smoltification traits in c. 12 generations. Smoltification is a complex transformation – morphological, behavioural and physiological – preparing juvenile salmon for their outmigration to the marine environment. Because juveniles of the introduced populations now migrate into the lake rather than the ocean, the physiological preparations for salt water are no longer necessary. I will test for adaptation in smoltification traits by comparing juveniles from a naturalized Great Lakes population with those from the ancestral population, raised in a common garden.