Western University BiologyWestern Science

Archived Friday Philosophicals Abstracts - Winter Semester 2013

April 19, 2013 - Special Lecture in Philosophy of Biology

April 5, 2013

Catherine Gao: Social immunity and the expression of immune-relevant genes in the Eastern subterranean termite

Catherine Gao Philosophical

Supervisor: Dr. Graham Thompson
Degree: Ph.D. Candidate

For social insects, there are two levels of immune defense. Individual immunity consists of a conserved innate response involving the expression of antimicrobials upon infection. Social immunity, by contrast, is a derived phenomenon specific to social animals whereby individuals cooperate to reduce each other’s pathogen load. Using the Eastern subterranean termite as a model, I studied the ability of termites to mount a social immune response. First, I show that group-level behaviours do confer social immunity in the face of infection, and that this immunity is dependent, not on the number, but on the nature of social interactions. Second, I use molecular techniques to identify several termite immune genes, and show their expression to vary as a function of social context.

Eric Moise

Eric Moise Philosophical

Supervisor: Dr. Hugh Henry
Degree: Ph.D. Candidate

Field experiments are commonly used to investigating potential ecosystem consequences of climate warming and nitrogen deposition, yet the lack of experimental control relative to laboratory-based investigations may present influential artifacts. For instance, herbivores may concentrate feeding to plots offering beneficial microhabitat or high quality resources. For this study exclosures were employed to explore interactions of herbivory with warming and nitrogen addition manipulations. Exclusion of rodents from nitrogen plots resulted in significantly greater biomass than did their exclusion from non-fertilized plots. Likewise, mollusc exclusion from warmed plots resulted in significantly greater biomass than did their exclusion for ambient temperate plots. Overall, these results suggest quantification of plant responses in global change field experiments may be substantially influenced by species-specific herbivore sensitivities to warming and nitrogen addition.

March 22, 2013

Brendan J. McCabe: First flight: energetics and digestive physiology of songbirds during their first migratory journey

Brendan McCabe Philosophical

Supervisor: Dr. Chris G. Guglielmo
Degree: Ph.D. Candidate

Young songbirds make their first migration when they are only a few months old and tend to do less well compared with adults in several measures of migratory performance, including length of stopover. Underlying physiological factors, such as energy expenditure and digestive efficiency, may contribute to longer stopover durations of juveniles. For juvenile and adult songbirds during fall migration, I measured body compositions using quantitative magnetic resonance and dissection, basal metabolic rates using open-flow respirometry, and digestive efficiencies using total collection feeding trials. Juveniles tended to have larger digestive organs and higher metabolic rates, but equivalent digestive efficiencies. These results suggest that juveniles are physiologically different than adults during fall migration, and that these differences provide greater challenges to juveniles during their first migration.

Mat Vankoughnett: The combined effects of soil freezing and nitrogen deposition on plant and soil nitrogen retention

Mat Vankoughnett Philosophical

Supervisor: Dr. Hugh Henry
Degree: Ph.D. Candidate

In northern temperate regions, climate warming is predicted to decrease the proportion of precipitation that falls as snow. Reduced snow cover can increase soil freezing, causing microbial lysis, disruption of soil aggregates, and damage to roots, ultimately leading to decreased ecosystem nitrogen retention. Coupled with increased atmospheric nitrogen deposition and ecosystem nitrogen saturation over the next century, nitrogen losses may be exacerbated. The objective of my study was to investigate the interactive effects of soil freezing and nitrogen deposition on nitrogen retention in a temperate ecosystem. My results indicate that soil freezing can enhance winter ecosystem nitrogen losses, and also lead to decreased retention of nitrogen deposition during the summer. My findings highlight the likely importance of winter climate change in modifying ecosystem nitrogen retention.

March 15, 2013

Emma Mullen: Gene Networks for Altruism in the Honey Beey

Emma Mullen Philosophical

Supervisor: Dr. Graham Thompson
Degree: M.Sc. Candidate

Kin selection explains how social behaviour can evolve at the gene level, but it does not identify which genes are necessary for the expression of altruism. Using microarray data, we reconstructed ten provisional knowledge-based gene networks that describe altruism by means of ovary activation and de-activation in the honey bee. Nine out of ten networks were enriched for Gene Ontology terms pertaining to reproduction, and the hub genes of each network consist of either transcription factors, signaling genes, or genes involved in oogenesis. The relatively low (17%) gene overlap among networks suggests bees are using different suites of genes throughout their behavioural ontogeny to regulate ovary activation, and taken together these networks provide the first insights of the molecular interactions necessary for reproductive altruism.

Drew Moore: Measuring vocal performance and examining the relationship between performance, morphology and other song characteristics

Drew Moore Philosophical

Supervisor: Dr. Beth MacDougall-Shackleton
Degree: M.Sc. Candidate

Birdsong, like many mating signals, has multiple aspects to which receivers can attend. One such aspect is vocal performance, defined as the ability to perform physically demanding song. My project aimed to determine the best way to measure vocal performance in birds with complex song such as the song sparrow (Melospiza melodia), and to examine relationships between performance, morphological constraints, and other song characteristics. I found that distinguishing between simple and complex trills, and measuring maximum performance is the most effective measure of vocal performance. Bill size does not constrain performance, however vocal performance is positively correlated with a bird’s song repertoire size, a known proxy for male quality. This suggests that vocal performance may also encode important information for the receiver about male quality.

March 8, 2013

Joanna Konopka: Reproductive biology of Western bean cutworm (Striacosta albicosta) females

Joanna Konopka

Supervisor: Dr. Jeremy McNeil
Degree: M.Sc. Candidate

The western bean cutworm (WBC), an insect pest of corn and dry beans, has recently expanded its range eastward reaching Ontario and Quebec provinces. Since environmental conditions can affect patterns of release from artificial lures in pheromone traps (used in pest management programs) and from feral insect females, this project aims to investigate the calling behaviour and sex pheromone synthesis of WBC female moths under different abiotic (temperature and relative humidity) and biotic (age and mating status) conditions. I will present results on age of female sexual maturation, and patterns of calling behaviour in virgin females held under different abiotic and biotic conditions.

Yelin Xu: The effect of growth on age and size at maturity in female kokanee salmon

Yelin Xu Philosophical

Supervisor: Dr. Yolanda Morbey
Degree: M.Sc. Candidate

Different reproductive phenotypes occur in female kokanee salmon (Oncorhynchus nerka) returning in the fall spawning season to Meadow Creek, British Columbia. Female kokanees either arrive in the creek with a changed red skin color, which is most common, or as others that maintain their silver colour. Red- and silver-arriving females differ in age and size at maturity with the silver females younger and smaller than the red ones. During the life history of a fish, growth is one of the characteristics whichplay a significant role in decision-making of age and size at maturity. Theoretically,rapid growing fish tend to mature younger to decrease pre-maturation mortality risk, while the slow growing fish prefer delayed maturation with increased fecundity. The aim of my project is to use otolith growth as a proxy to compare fish growth in different life stages between two phenotypes, thereby investigating to what degree growth influences the difference in age and size at maturity of female kokanee salmon.

March 1, 2013

Michael Thorn: A comparison of Chinook Salmon (Oncorhynchus tshawytscha) Egg Quality and Developmental Traits Among Three Great Lakes Tributaries

Michael Thorn Philosophical

Supervisor: Dr. Yolanda Morbey
Degree: M.Sc. Candidate

Chinook salmon (Oncorhynchus tshawytscha) were first introduced to the Great Lakes in the late 1960’s with embryos from the Green River, Washington. Since then, they have colonized tributaries throughout the Great Lakes. In salmonid fishes, egg size is known to be locally adapted and capable of rapid evolution in novel environments. The purpose of my research is to test for the adaptation of egg size in Great Lakes Chinook salmon populations. I first tested for differences in egg size among populations after controlling for the effect of female size. Egg size differed among populations with 20% and 23% of the variance explained by female size and among population differences respectively. I also found that egg size accounts for much of the variance in early growth.

Jasmine Farhan: Temperature, wind speed and relative humidity affecting the number of male western bean cutworm, Stricosta albicosta, caught in pheromone traps

Jasmine Farhan Philosophical

Supervisor: Dr. Jeremy McNeil
Degree: M.Sc. Candidate

Pheromone traps are often an important component of IPM programs. However, as with the western bean cutworm (WBC), Striacosta albicosta in the Great Lakes region, trap catches are not good indicators of subsequent infestations. In part, this is because we do not have good data on the influence of abiotic factors on either the emission of, or response to, pheromones. I will present the results of a two-year field study examining the effects of temperature, wind speed and relative humidity on the number of WBC males captured in pheromone traps.

February 15, 2013

Philip Wilson: Habitat selection by Long-tailed Ducks (Clangula hyemalis) overwintering at Lake Ontario

Philip Wilson Philosophical

Supervisor: Dr. Scott Petrie
Co-supervisor: Dr. Chris Guglielmo
Degree: M.Sc. Candidate

Shortly after the introduction of Dreissenid mussels to the lower Great Lakes in the mid-1980s, the abundance of diving and sea ducks increased rapidly during winter. An increase in food combined with warmer winter temperatures and decreased ice cover may be contributing to the increased abundance of overwintering Long-tailed ducks at Lake Ontario. Plans to develop offshore areas with industrial wind turbines may influence habitat use by Long-tailed Ducks. Preliminary results suggest that habitats are used offshore nocturnally for roosting and nearshore diurnally where they select areas to forage in shallower water with a greater abundance of macroinvertebrates. My goal is to develop relative probabilities of habitat use across Lake Ontario to determine areas where offshore industrial wind turbines would interfere with foraging and roosting.

Leslie Erdman: Effect of trophic level on the stable hydrogen isotopic composition of bat fur

Leslie Erdman Philosophical

Supervisors: Dr. Brock Fenton and Dr. Fred Longstaffe
Degree: M.Sc. Candidate

Stable isotope analysis has become an important tool for studying bat ecology. Stable hydrogen isotopic compositions from fur (δ 2H fur) are particularly useful for determining the extent and occurrence of migration in bats. Little is known, however, about the effect of trophic level on δ 2H fur values. Understanding the effect of trophic level on δ 2H fur variation can help us refine our understanding of migration in bats as well as provide information about their diets. I will conduct stable isotope analyses on several bat species, both captive and wild, to determine if there is an effect of trophic level on the stable hydrogen isotopic composition of bat fur.

February 8, 2013

Kaylin Liznick: Explaining the increasing mercury trend in Lake Erie: the role of invasive species

Kaylin Liznick Philosophical

Supervisor: Dr. Brian Branfireun
Degree: M.Sc. Candidate

Long-term monitoring has revealed a recent increasing trend in mercury (Hg) levels in the top predatory fish of Lake Erie, despite the decline in regional atmospheric Hg emissions. This project explores the roles that recently introduced invaders, such as the round goby and dreissenid mussels, play in the transfer of Hg and its methylated form (MeHg) throughout the lake-wide food web. Results show that aqueous total and methyl Hg levels are low, often beneath EPA and instrument detection levels. Measured Hg concentrations in goby, yellow perch and walleye corresponded with literature values, indicating an inter-basin difference from West to East. Future work aims to analyze findings with the perspective of trophic transfer from lower foodweb compartments to clarify the rate of transfer and factors of biomagnification.

Bryana McWhirter: The Interactive Effects of Warming and Nitrogen Deposition on Tree Establishment in Temperate Old Fields

Bryana McWhirter

Supervisor: Dr. Hugh Henry
Degree: M.Sc. Candidate

Old field habitats are increasing in number as areas previously utilized for agricultural production have been abandoned or converted into naturalized areas. With time and lack of disturbance, old fields develop into secondary forest communities. However, there is concern that climate warming and increased atmospheric nitrogen deposition over the next century may alter plant community successional trajectories. Changes to growing season length and timing as well as nitrogen availability may affect the establishment and competitive abilities of woody seedlings in grass-dominated communities. In this study, I am investigating the effects of both climate warming and increased nitrogen addition on the germination success, establishment, and first year’s productivity of five early successional tree and shrub species in a temperate old field.

February 1, 2013

Marek Allen: "Mommy, I'm Scared": Assessing perceived predation risk effects on juveniles

Marek Allen Philosophical

Supervisor: Dr. Liana Zanette
Degree: Ph.D. Candidate

Studies usually only measure how many individuals predators kill, and do not assess the equally and sometimes stronger effect of predator-induced fear (i.e. perceived predation risk) on prey populations. I am proposing to assess how perceived predation risk affects prey population dynamics through effects on juveniles, an important but understudied life-history stage. I will fill this gap by manipulating perceived predation risk in wild, free-living song sparrows (Melospiza melodia). Fates of offspring will be monitored once they have left the nest (i.e. fledged) until their death or recruitment into a population the following season, and I will assess the behavioural and physiological reasons why they live or die.

Christopher Austin: Do some like it hot? Thermal Adaptation in Drosophila

Christopher Austin Philosophical

Supervisor: Dr. Amanda Moehring
Degree: M.Sc. Candidate

With the current shifts in global climate, it is critical for us to understand how organisms have adapted to local climate. While D. simulans is thought to be a more genetically variable species, its sister species, D. melanogaster, is thought to be more genetically adapted to its local environment. I tested the hypothesis that D. simulans is more plastic than D. melanogaster. To do this, I determined whether populations of D. simulans and D. melanogaster have adapted to their local environment by comparing their optimum temperatures range at a variety of life stages. Preliminary results indicate that D. simulans has equal levels of fitness in a very wide range of temperatures, whereas D. melanogaster is more sensitive to changes in temperature.

January 25, 2013

Catherine Dieleman: What is ecosystem function?

Catherine Dieleman Philosophical

Supervisor: Dr. Brian Branfireun
Degree: Ph.D. Candidate

Anthropogenically-driven habitat loss is the single greatest threat to the biodiversity and functions of Earth’s ecosystems. Therefore, an understanding of, and effective means to quantify, anthropogenic impacts on ecosystem function are urgently needed if we are to effectively mitigate further impact. The aim of my doctoral research is to develop a set of quantitative metrics to measure ecosystem function using wetlands as a model system. In order to even begin to address this overall goal, the first part of my work has led to a critical examination of the terminology and assumptions in the field of ecosystem function research. My conclusion thus far is that scientific progress in this area of Ecology is hindered by the use of ill-defined language and unquantifiable metrics that render generalizable principles elusive.

January 18, 2013

Heather MacGillivray: The effect of parasites on the genetic composition of song sparrow populations (Melospiza melodia)

Heather MacGillivray

Supervisor: Dr. Beth MacDougall-Shackleton
Degree: M.Sc. Candidate

Parasites comprise many of the known species in the world and they have significant effects on the health and reproductive success of their hosts. Theory suggests that locally good genes may allow an individual to resist parasites with which they are familiar. This may in turn be an isolating mechanism that can cause populations to genetically diverge. In a song sparrow population in southern Ontario, recent work has improved the ability to distinguish local from non-local individuals more accurately than previously possible. Using multiple measures of immunity and parasite counts, I intend to determine whether local individuals carry more parasites than non-local birds, and also to test whether local birds have inherently greater immunocompetence than their non-local counterparts.

Kayla Gradil: The adaptive capacity of thermal tolerance in Atlantic salmon: reintroduction to Lake Ontario

Kayla Gradil Philosophical

Supervisor: Dr. Bryan Neff
Degree: M.Sc. Candidate

Global climate change is projected to have widespread effects, threatening the viability of natural populations and biological diversity. The ability of species to adjust to climate change is modulated by its adaptive capacity, which likely involves evolutionary adaptation. Physiological processes of aquatic ectotherms critically depend on their thermal environment, such that optima for performance corresponds to historically experienced temperatures. Atlantic salmon (Salmo salar) were extirpated from Lake Ontario by 1900, and current restoration efforts are focused on three candidate source populations. The aim of my project is to evaluate thermal tolerance and its underlying adaptive capacity in these candidate source populations, and identify which would have the highest relative survival and thereby long-term restoration success in Lake Ontario in projected warming temperatures.

January 11, 2013

Matthew Turnbull: The effects of climate change on Collembola community functional trait distribution

Matthew Turnbull Philosophical

Supervisor: Dr. Zoë Lindo
Degree: M.Sc. Candidate

Collembola, also known as springtails, are an ancient and globally distributed group of arthropod soil mesofauna with an important role in ecological processes including decomposition, nutrient cycling, and microbial activity mediation. Their variety of feeding strategies, high densities, and ubiquity make them a major component of soil functioning. However, little is known about how springtail communities will respond to anthropogenic environmental changes to temperature, moisture, and CO2. This is further complicated by springtail taxonomic and morphological variation, making classic richness-based diversity metrics less meaningful predictors of functioning. My research uses a full factorial design to study the effects of environmental change variables on Collembolan community composition and trait distribution, with an eye towards resulting effects on associated microbes, fungi, and plants.

Tosha Kelly: Migratory immunocompetence: An investigation of partial migration in Song sparrows (Melospiza melodia)

Tosha Kelly Philosophical

Supervisors: Dr. Elizabeth MacDougall-Shackleton and Dr. Scott MacDougall-Shackleton
Degree: M.Sc. Candidate

Pathogens present strong selective pressures upon hosts, thus trade-offs involving immunity are crucial in determining optimal life-history decisions. Life-history theory predicts animals face trade-offs with immune defence while performing strenuous exercise, such as migratory flight. Long migratory flight creates a lose-lose scenario where, as travel distance increases, there is an increasing energetic cost while encountering a growing number of foreign pathogens and parasites. Intraspecific variation of migratory distance in a well-studied song sparrow population will be determined using stable isotope analysis. These distances will be compared to a range of immune techniques that assess diverse aspects of the immune response. My objective is to determine whether trade-offs exist within the innate and adaptive branches of the immune system to optimize life-history decisions and energy allocation.