Archived Friday Philosophicals abstracts - Winter Semester 2016

Supervisor: Dr. Graham Thompson
Termites are eusocial insects that live in kin-based colonies, where a small number of reproductives are supported by a large number of subfertile workers and soldiers. Some of this variation in caste phenotype may be explained by genes that regulate individual development in a caste-specific manner. I tested this hypothesis by using mRNA-seq analysis to detect the presence and expression of protein encoding genes in the worker, soldier, and reproductive nymph castes of the Eastern subterranean termite. I assembled a transcriptome from nine sequence libraries derived from three reproductively isolated populations, and provisionally annotated 29461 transcripts for gene function. Using this transcriptomic data, I identified 141 genes that are uniquely expressed by caste. This gene set contains several regulators of development such as hexamerins and a growth arrest protein. My finding helps to clarify the genetic basis of caste differentiation in a common pest species of subterranean termite.

Personal information:
I became fascinated with insects during my previous employment with the Canadian National Collection of Insects. At the same time, I also saw the emergence of large data genomic technology being used to answer evolutionary questions. When I decided to pursue a master’s degree, I wanted a project that would combine both of my interests. During my stay here at Western, I started the Mustang Bioinformatics Club with Jantina Toxopeus to provide other graduate students with bioinformatic support.

Supervisor – Dr. Ian Scott Co-Supervisor – Dr. Jeremy McNeil

Insecticide resistance continues to develop as a problem within agricultural systems. New non-chemical routes of pest reduction are required to reduce pest populations and increase agricultural yield in response to rising levels of resistance. Trichoplusia ni (Hübner) (Cabbage Looper Moth) is a problematic agricultural pest in standard agriculture, and greenhouses, with a wide range of possible host plants including cabbage, tomato, and bell peppers. They have developed resistance to a number of pest management strategies, and serve as a model organism in this study of LeCCD1 transgenic Solanum lycopersicum (L) (tomato) trap crop capabilities. Trap cropping is the practice of planting highly attractive, disposable plants within the grow area of a main crop with the purpose of drawing pests away from harvested plants. This design aims to verify Cabbage Looper Moth attractance to LeCCD1 tomatoes, as well as assess trap crop effectiveness against this pest in model growing arrangements.

Supervisor: Dr. Liana Zanette
Predators affect prey populations not only through direct killing, but also through the perception of predation risk.  Responding to predator threats is critical for prey survival, however perceived predation risk can have lasting effects ranging from individual changes in neurobiology up to the population level.  My research focuses on the lasting effects of predator ‘fear’ on the avian brain.  I will be using auditory playbacks to manipulate predation risk in black-capped chickadees (Poecile atricapillus) in acoustic isolation and brown-headed cowbirds (Molothrus ater) in large outdoor aviaries. I will be looking for long lasting changes in brain morphology and activation in regions thought to be involved in the avian fear network.  My research aims to connect laboratory methods used to quantify the effects of fear in the brain with behavioural and physiological changes found from perceived predation risk in the field.

Supervisor: Bryan Neff
The major histocompatibility (MHC) genes encode cell-surface proteins that are responsible for presenting antigen peptides to immune cells. Aside from its vital immune function, the highly variable MHC genes have also been linked to mate choice in multiple species. One hypothesis is that females of some species choose their mates based on dissimilarity at the MHC in order to produce heterozygous offspring with improved immunocompetence. I will use bluegill (Lepomis macrochirus) as a study species for MHC-based mate choice. The MHC regions of bluegill mating pairs caught in the act of spawning will be investigated using next gen sequencing techniques.

Supervisors: J.N. McNeil, K.A. Hobson
Temperature is a major abiotic factor determining distribution and population dynamics of insects. Seasonal changes in temperature are also important cues related to habitat quality and when decreasing temperature (and shortening daylength) indicate impending habitat deterioration insects enter diapause locally until conditions improve or emigrate elsewhere.  However, increased variability in temperature conditions as a result of climate change may significantly impact the distribution and seasonal biology of beneficial and pest species.
Fields and McNeil (1984) showed the true armyworm, a sporadic pest, did not overwinter in Canada but immigrated in each spring. However, there are now more frequent suggesting there may be local overwintering populations. I repeated their experiments and found armyworm still cannot survive here. Therefore, I propose using stable isotopes to examine the origin of immigrants, testing the hypothesis that the higher frequency of outbreaks is the result of armyworm populations overwintering further north than in the past.

Supervisor: David Roy Smith
Mitochondria and plastids originated from independent endosymbiotic events over 1.5 billion years ago. These organelles evolved and kept their genetic material. The first organelle chromosomes to be sequenced were circular and relatively simple. However, in the last 30 years of organelle genetics, mitochondrial and plastids genomes proved to be widely diverse in size, content and structure. The modes of organelle genome transcription are similarly variable and difficult to explain under purely adaptive forces. Here, I will present how intricate organelle transcription can be, particularly in protists. I will also argue how current technologies are being underused to better characterize these processes and what we can do to overcome it.
A bit about me: I was raised in a farm, which brought me to Biology. Luckily, I attended a school purely based on Evolution (University of Sao Paulo, campus Ribeirao Preto). Then, my passion for evolutionary biology just kept increasing after working in Portugal (with fungi taxonomy at the University of Minho) and Canada (with evolution of aging in Volvox carteri at the University of New Brunswick). Now, Im here at Western continuing my path on evolutionary biology.

Supervisors: Yolanda Morbey and Chris Guglielmo
Protandry, meaning “males first”, is a common pattern of sex-biased timing that is seen across a diverse range of animal taxa (insects, amphibians, fish, mammals, and birds). In migratory birds, protandry is the norm, and is apparent in many events leading up to and including arrival at breeding sites. I will be studying the mechanisms underlying protandry in a migratory songbird, the Black-throated Blue Warbler (Setophaga caerulescens). I will capture Black-throated Blue Warblers during fall migration, keep them in captivity over winter, photostimulate them to begin migration, and then radio-tag and release them during spring migration at Long Point, Ontario, to monitor stopover behaviour and timing of departure. This will be the first study to estimate stopover duration in migratory birds with a known arrival date.

Supervisor: Graham Thompson
Social insects often communicate reproductive roles through pheromones. In honey bee colonies both drone and worker castes cue their reproductive behaviour from queen mandibular pheromone. Drones are sexually attracted to pheromone-emitting virgin queens, while workers respond to this same pheromone with selfless reproductive help. Studies within our lab suggest that this multi-purpose reproductive signal is inadvertently effective on nonspecific recipients, and may elicit comparable responses from male and female non-social insects. Remarkably, QMP de-activates Drosophila ovaries, much as it does in workers. QMP may also accelerate mating effort by males, as it normally does with drones. In the present study, I build on these bee-fly comparisons to test if male or female flies are positively attracted to volatile QMP, and further use the fly model (NFAT) to map the neural receptors that mediate this behavioural response.

MSc candidate
Supervisor: Dr. Zoë Lindo
Boreal peatlands are ecosystems that are receiving heightened interest due to their large carbon sequestration abilities and low decomposition rates, making them significant sinks of carbon. There is a growing body of literature that suggests aboveground-belowground linkages, or plant-soil interactions, are important for ecosystem functioning and integral to the delivery of ecosystem services like carbon and nutrient cycling. Trait-based approaches in ecology are being increasingly used to quantify functional diversity of organisms to elucidate ecosystem functioning, and aim to understand how plants respond to environmental conditions and effect processes. Examining aboveground-belowground linkages with a traits-based approach in the context of peatlands allows for novel examination of traditional questions, like how are plant communities shaped by the environment, and how do plants influence ecosystem process like decomposition? My master’s project explores these questions by performing an observational study linking plant species to soil variables, and two reciprocal litterbag transplant experiments testing for decomposer-litter affinities.
A bit about me: My passion for peatland research was cultivated during a stint at the Ontario Ministry of Natural Resources and Forestry in Sault Ste Marie, where I participated in peat collection and permafrost coring, and also met Dr. Lindo conducting this field work.

Supervisor: Dr. Liana Zanette  
Predators  not only kill prey, but through the 'fear' of predators induce costly anti-predatory responses.  These anti-predatory costs among prey individuals, may scale up to effects on prey populations as a whole, through effects on prey reproduction, juvenile survival, and/or adult survival.  My thesis focuses on how the perceived risk of predation affects prey population dynamics through effects on juveniles.  I monitored the fate of juvenile song sparrows (Melospiza melodia) reared in environments manipulated with audio playbacks to be perceived as either a high or low predation risk environment. Scared juveniles had lower survival compared to juveniles reared in a low risk environment.  Furthermore, scared juvenile survivors were in poorer condition which may have adverse, possibly even lifelong effects.  Demonstrating that the fear of predators can have a greater net effect on wildlife prey populations than we previously showed with reductions in offspring production alone.

Supervisor: Nusha Keyghobadi
Due to the current rate of climate change and the warming patterns it has caused, in many alpine habitats the treeline is ascending towards the normally colder mountain peaks. This results in shrinking alpine habitats and fragmentation of existing populations of local organisms. For the purpose of conservation, it is imperative to understand the effects of individual landscape elements on the dispersal of organisms. My project entails creating resistance surface map models in ArcGIS to examine the effects of the landscape on movement and gene flow among populations of alpine butterfly Parnassius smintheusin Kananaskis, Alberta. The variables of interest are land cover type and elevation changes, and these will be used to create an isolation by resistance model. With this model, areas of high connectivity and traffic can be determined and targeted for conservation purposes.

Climate change is expected to increase atmospheric CO₂ levels and global temperatures. In Boreal peatlands, increased temperature is expected to directly increase decomposition rates, but also indirectly through changes in plant species composition and litter inputs. I used three species of peatland plants grown at 430 ppm and 750 ppm CO₂ for a year to quantify litter decomposability and carbon release. My results suggest that predicted changes in plant species composition may increase decomposition rates and labile carbon inputs to soil systems. However at the same time, plants grown under elevated CO₂ demonstrated reduced labile carbon inputs. Understanding decomposition processes in Boreal peatlands under future climate scenarios will help predict whether these systems will remain a carbon sink or possibly become a global carbon source.

Termites, as social insects live in kin-based colonies with defined boundaries that are generally actively defended against intruders, including individuals from conspecific colonies based on chemical signatures. However, the eastern subterranean termite (Reticulitermes flavipes) was accidentally introduced into Toronto where it forms expansive supercolonies that differ from the separate colonies observed in their native range. In addition there are now colony locales in southwestern Ontario with significant genetic differences.  It has been argued that in habitats with limited resources the benefits of sharing outweigh the costs of aggressive defense. Therefore, using a behavior based study I tested the hypothesis that intra-specific aggression varies with geographic distance. I found no evidence of overt aggressive behavior between individuals from Toronto (supercolonies) or Pelee (separate). However, it was evident that workers from Toronto and Pelee did not mix in an assay where they shared a common food resource, which indicates that social order is still maintained, possibly through cuticular hydrocarbon profiles. 

Supervisor: Bryan Neff
Atlantic salmon (Salmo salar) were once abundant in Lake Ontario, but were extirpated by 1898. Efforts to reintroduce Atlantic salmon into Lake Ontario have not yet succeeded. One potential obstacle is the introduction of invasive forage fish, which can lead to a thiamine deficiency in salmonids. Previous studies on thiamine deficiency have documented negative effects, including lower swimming performance and body condition. To study the effects of thiamine deficiency, our salmon have been fed either a high-thiamine diet or a low-thiamine diet. Three populations of Atlantic salmon will be used to determine which strain has the best performance under a low-thiamine diet. Crosses will be done to investigate the effects of thiamine deficiency on reproduction, including hatching success and survival. Results will provide insight into which population may be better suited to the current environmental conditions of Lake Ontario, and how to manage the reintroduction efforts of Atlantic salmon.

Supervisor: Brian Branfireun
Northern peatlands disproportionately contribute methylmercury, a bioaccumulating and biomagnifying neurotoxin and endocrine disruptor, to aquatic biota in downstream waters ultimately affecting humans. Sulphate reducing bacteria (obligate anaerobes) are mainly responsible for methylmercury production in anoxic peat soils. The production of methylmercury is largely controlled by the availability of sulphate reduction reactants (sulphate as an electron-acceptor, a labile carbon substrate and bioavailable mercury), whereas the specific hydrologic properties of any particular peatland control transport. The effects of climate change may enhance the production and transport of methylmercury in northern peatlands. Using two field investigations: (1) measuring the response of in situ net methylmercury production under experimentally heated soil treatments in two northern peatlands and (2) determining the hydrologic connection between two streams draining a peatland, will provide researchers, land managers, and policy makers greater understanding of methylmercury production and transport in northern peatland ecosystems.

Supervisors: Ian Scott & Graham Thompson
In today's day and age, food is being produced at an arithmetic rate while human population is growing at an exponential rate, making crop yield and protection increasingly important. Currently, insect pests and pathogens are responsible for approximately 25-30% of crop loss. In addition, the incidence of pesticide resistance is also increasing, further threatening crop yield. The use of RNA interference (RNAi) is one promising means of pest management where double-stranded RNA (dsRNA) silences the messenger RNA (mRNA) of a target based on the genetic sequence selected, resulting in lethality and developmental delays. By utilizing RNAi, applying it to transgenic Micro-Tom tomatoes (Solanum lycopersicum cv.), which have a high attraction for the greenhouse whitefly (Trialeurodes vaporariorum), a new efficient trap crop may be developed. This may be the next step in pest management and in the phasing out of chemical pesticides and insecticides.

Genetic diversity is critical in shaping the adaptive capacity of avian populations and the fitness of individuals. Genome-wide heterozygosity is usually assessed using selectively neutral markers such as microsatellites. However, neutral-locus heterozygosity may not accurately reflect heterozygosity at protein-coding sites that may be under selective pressure. The major histocompatibility complex (MHC) is the most polymorphic region in the vertebrate genome. Additionally, MHC diversity is found to be associated with immunocompetence, which is related to survivorship. DNA samples were collected from a population of Song Sparrows (Melospiza melodia) and analyzed to assess heterozygosity at 12 microsatellites. Birds were genotyped at MHC class II b using the Illumina MiSeq platform. Our results show that microsatellite heterozygosity does not predict MHC diversity. We also found that MHC allele number did not correlate with overwinter. This information will aid in conservation and management decisions when determining how to properly assess genetic diversity of endangered populations.

Vegetative reproduction utilizes stem, leaf, or root derived organs to form clonal offspring and is an inherent feature of the body plans of many plants.   Growth allocation often favours vegetative organ production over that of sexual reproduction and the depth of clonal organs can aid in freezing avoidance. Frost tolerance decreases dependence upon site availability and recruitment can be facilitated by the greater supply of resources to clonal offspring.
To test the effects of freezing on vegetative organ survival and plant recruitment I will use snow removal, freezing, and functional trait analysis.  Plants will be subjected to freezing temperatures after which organ survival, recruitment, and organ investment will be measured.  Snow removal and freezing chambers will be used to study the effects of organ depth.  Functional trait literature, phylogenetic information, and geographic distribution will also be used to gain further insight on the distribution and qualities of these functional traits.

Choosing the right mate is of central importance to biological fitness. In Drosophila, olfactory and gustatory cues in the form of cuticular hydrocarbons (CHCs) are used to assess the identity and quality of potential mates. Since Drosophila melanogaster produces infertile offspring when it forms hybrids with any of its sister species, those individuals which are the most discriminating against flies that do not express the appropriate CHC profile will have the highest fitness, as they will preferentially mate with individuals of the same species to form fertile offspring. Here, I will endeavour to identify key genes involved in species differences in CHC production. Since different CHC profiles constitute a reproductive barrier across Drosophila species, genes identified in this study will provide insight into the complex mechanisms of speciation in insects.