Western University BiologyWestern Science

Archived Friday Philosophicals abstracts - Fall Semester 2016

November 25, 2016

Priya Mahabir: Identifying the neural basis of female receptivity within and between Drosophila species.

Priya Mahabir photoSupervisor: Dr. Amanda Moehring

The complex processes that regulate mate preference have been widely studied. Most studies to date have focused on the mechanisms that drive male mate choice, while those that underlie female mate preference remain largely unknown. Recent studies show that females in most species are the primary discerners of reproductive receptivity. In order to address the existing knowledge-gap, a combination of genetic tools will be employed, including temperature-sensitive gene disruption, in both D. melanogaster and D. simulans females to isolate regions of the brain responsible for female sexual receptivity or rejection. Identifying the neural basis of female receptivity, while of interest in its own right, will also contribute to our understanding of the origin of speciation and how neuronal circuits integrate multiple sources of information from various modalities to subsequently produce directed behaviours.

Kaitlyn Ludba: Fatal attraction: the volatile influences that will lead whiteflies to deadly encounters and the dsRNA responsible.

Kaitlyn Ludba photoSupervisor: Dr. Ian Scott & Graham Thompson

With global food security becoming increasingly important, and insecticide resistance on the rise, new insect pest management strategies need to be considered. One technology that shows potential is RNA interference, which silences target gene expression and can result in development delays, decreases in insecticide resistance, and lethality to pests. Other alternatives are trap crops, which attract pest species using either visual or olfactory cues. By targeting the olfactory senses, an attractant or arrestant effect can be observed; this has been seen in Trialeurodes vaporariorum (Westwood) using transgenic Micro-Tom tomatoes (Solanum lycopersicum) with enhanced carotenoid cleaving deoxygenase gene activity. By combining these attractive plants with RNA interference, a novel lethal trap crop model, which lures, and then kills by silencing vital gene targets, can be developed.

November 18, 2016

Jeff Martin: The effects of temperature on cognitive abilities in black-capped chickadees (Poecile atricapillus).

Jeff Martin photoSupervisor: Dr. David Sherry

Harsh Climates can cause avian populations to endure stressful conditions for extended periods of time. Black-capped chickadees (Poecile atricapillus) inhabit much of North America, including southern Ontario, and are subjected to local winter conditions for several months of the year. Previous studies have shown that populations of birds inhabiting harsh climates benefit from advanced cognitive function. These benefits are found in populations from different geographic regions, testing components of harshness such as latitude and altitude. Though temperature is closely related to other components of harshness, few studies have isolated temperature. Here, I examine local populations to assess the impact of harsh seasonal winters on cognition.

Heather Ward: The Genetic and Environmental Basis for CHC Biosynthesis in Drosophila.

Heather Ward photoSupervisor: Dr. Amanda Moehring

The type and quantity of cuticular hydrocarbons (CHCs) expressed by Drosophila are determined by the complex interplay between the fly’s genetic background, its diet, and the commensal microbes that colonize its gut. Since the CHC profile of a fly is intrinsically linked to its reproductive fitness, alterations to the fly’s profile due to input from any of these mechanisms can potentially lead to reproductive isolation and eventual speciation. Using genetic and molecular techniques, this study aims to separate out and independently examine each of the factors contributing to CHC variation in Drosophila in order to better understand the mechanisms that may give rise to behavioural isolation and speciation in insects.

November 11, 2016

Justin Croft: Tracking behavioural and neuronal responses to social pheromones: Insight from a pre-social model.

Justin Croft photoSupervisor: Dr. Graham Thompson

In honey bee colonies the queen signals fecundity to her worker daughters via ovary-inhibiting queen pheromone, which renders them conditionally sterile. There is interest in identifying genes and neural circuits regulating this type of reproductive signalling, but honey bees are not ideal models in neuroimaging. In my study, I use Drosophila as an established behavioural genetic model to map neurons that respond to the queen bee’s ovary inhibiting pheromone. To do so, I use a calcium-channel activated neural imagining technique that allows me to identify pheromone-activated neurons within antennae. Through confocal imaging I have identified olfactory receptor neurons Or-49b, Or-56a and Or-98a as responsive to the social pheromone, and identify functional homologues of each receptor in the bee itself.

Asma Asemaninejad: The impacts of climate change on communities of fungi in boreal peatlands.

Asma Asemaninejad photoSupervisors: Dr. Greg Thorn and Dr. Zoë Lindo

Peatlands have an important role in global climate change through sequestration of atmospheric CO2. There is concern that altered fungal community function affected by climate change may turn peatlands from carbon sinks to carbon sources, greatly exacerbating the impacts of climate change. In order to gain a better insight into effects of climate change on the structure and function of these ecosystems, my research has focused on diversity and structure of fungal communities in natural environment in boreal peatlands and in mesocosm experiments to better understand the main and interactive effects of multiple drivers of climate change on fungal communities, and their function. These studies could help to provide a broader conceptual context of climate change and its consequences for carbon dynamics of boreal peatlands. .

November 4, 2016

Rachel Chambers: Plants on the edge: fields, forests, and grassland gradients.

Rachel Chambers photoSupervisor – Dr. Zoë Lindo

It is estimated that the last 200 years has seen the loss of 99% of North American grasslands through conversion to agriculture. In southern Ontario, urban and agricultural landscapes have replaced all but fragments of tallgrass prairie habitat. Currently, grassland restoration initiatives convert land, such as former agricultural fields, to restored grasslands. However, many of the areas targeted for restoration are small, isolated patches surrounded by active agriculture or forested areas. My project looks at such restored grasslands, planted by Nature Conservancy Canada, where I measured plant diversity in association with environmental variables at varying distances from adjacent forest and agriculture, in order to explain patterns in plant composition. This research could inform future restoration plantings and help determine minimum grassland patch sizes.

Benoit Talbot: Evolutionary genetic aspects of host-parasite interactions in generalist ectoparasites.

Benoit Talbot photoSupervisor: Dr.Nusha Keyghobadi and Dr. Brock Fenton

Many parasites rely on their hosts for dispersal, and we thus expect their movements to be linked. However, it was recently emphasized that generalist ectoparasites and highly mobile hosts might display very different gene flow patterns. In my project, I wanted to see how similar gene flow patterns are between Cimex adjunctus, a generalist ectoparasite of bats, and its bat hosts. In the same genus as C. adjunctus, few species are associated with humans, and others with swallows. Parasite species may display genetic signature representative of the host with which they associate. In my project, I also wanted to know how hosts affect neutral and adaptive genetic variation in generalist ectoparasites. Overall, I found that hosts clearly affect their parasites, but sometimes in unusual ways.

October 21, 2016

Leanne Grieves: Spatiotemporal variation in MHC diversity, parasitism, and olfactory-based mate choice in a migratory songbird.

Leanne Grieves photoSupervisor – Dr. Beth MacDougall-Shackleton

Major histocompatibility complex (MHC) genetic diversity is maintained largely by pathogen-mediated selection and sexual selection should favour the ability to assess MHC. MHC genotype is assessed via olfaction in several taxa, but this has been largely overlooked in birds. Recent evidence indicates that MHC-genotype and preen oil composition are correlated, but whether birds use this information to assess potential mates is unknown. MHC heterozygosity has also been linked to disease resistance, and preen oil odour thus provides a compelling potential mechanism for both MHC-based mate choice and disease avoidance. I will test whether song sparrows (Melospiza melodia) use preen oil odour to preferentially associate with both MHC-dissimilar and uninfected conspecifics. My research may reveal that chemical communication in birds is more common than previously believed.

Badru Mugerwa: Using wildlife’s fear response to humans and commensals (dogs) to experimentally quantify the extent of poaching.

Badru Mugerwa's photoSupervisor: Dr. Liana Zanette

Poaching drives biodiversity loss, yet there have been no means to systematically quantify its extent. Current methods are fraught with problems ranging from low statistical robustness to unreliable answers given by suspected poachers. I use an automated camera and playback system that when triggered by motion broadcasts a sound, and films the animal’s reaction, to experimentally quantify the level of fear poaching cues (sound of humans speaking, dogs barking) and a non-threatening noise (insects) inspire in a Ugandan wildlife community. Animals reacted fearfully to dogs by significantly fleeing and exhibiting more vigilance during dog playbacks, indicative of high poaching intensity, as dogs enter wildlife areas only in the company of poachers. Following validation, I will use the methodology to quantify poaching in a temperate system.