á Department of Biology Department of Biology Western University Science Logo

Archived Friday Philosophicals abstracts - Fall Semester 2015

December 04, 2015

Christine Dulal-Whiteway: Investigating the ichthyotoxic activities of Prymnesium parvum

Christine Dulal-Whiteway photoMSc. candidate
Supervisor: Dr. Charles Trick
Fish-killing flagellates are comprised of a taxonomically diverse set of Protists. Yet, the mechanisms by which these cells purportedly kill fish are fairly common. These HAB species can have dramatic effects on the aquaculture and fishery industries. The mass mortality of the affected marine organisms may result from individual or multiple toxic mechanisms. As Prymnesium parvum is a potentially invasive species, knowledge on the factors that shift the bloom from non-toxic to toxic is critical to our ability to predict the consequences of new or established blooms. For my project, I will be investigating the effects of light, temperature, salinity, macronutrients and micronutrients on toxin production in Prymnesium parvum.

Jeff Martin: Effects of Seasonally Harsh Climates on Avian Cognition 

Jeff Martin photoSupervisor: 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, by 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 seasonal temperatures on cognition. Environmental cues play a significant role in seasonal changes experienced by chickadees. These changes include changes within the brain.  By simulating different seasonal temperatures, I hope to find a relationship between seasonal conditions and cognitive functions in black-capped chickadees.

November 27, 2015

Ricky Kong: Freezing Stress Enhances the Survival and Growth of Poa Pratensis Under Severe Drought

Ricky Kong's photoSupervisor: Dr. Hugh Henry
Cross-protection is a phenomenon that occurs when exposure to one stress increases tolerance to a second different stress. Both frost and drought result in cellular dehydration and there are similar increases in protective compounds, but it is currently unknown whether exposure to frost can increase the survival and growth of plants under drought. Poa pratensis was frozen at 0, -5 or -10 for 3 d in the fall or spring and then subjected to no drought, a moderate drought, or a severe drought for 3 weeks in the summer. There was a significant interaction between frost and drought stress, where freezing resulted in higher survival, biomass and relative growth rates under severe drought. However, this interaction did not appear to be related to the retention of soluble sugars after freezing.

Christopher Hay: Little Mushrooms on the Prairie - or - Agaricomycetes of Ontario Tall Grass Prairies

Christopher Hay photoSupervisor: Dr. Greg Thorn
Tall grass prairies are known for their drastic reduction across North America and there is great interest in restoring them via conversion from agricultural land. Large-scale ecological studies of soil organisms have been greatly facilitated by the advent of high throughput sequencing. The Agaricomycetes are class of fungi found in prairie soils, best known for producing macro scale fruiting bodies or “mushrooms”. My study uses both mushroom and soil sequence data from prairies in various stages of recovery since agricultural use. Which factors drive prairie Agaricomycete composition? Years since tillage, dominant plants, soil minerals & organic matter, and geographic location will be considered. In the process, tall grass prairies in Ontario can be characterized by their mushroom diversity and comparisons will be made between my two sampling methods (mushroom collection vs. soil sequencing). This will lead to insights into fungal community succession, prairie restoration, and the natural history of our grasslands.

November 20, 2015

Katarina Doughty: The effects of hybridization on fitness related traits in Chinook Salmon (Oncorhynchus tshawytscha).

Katarina DoughtyEvolutionary biologists have long been interested in understanding how mating patterns contribute to fitness, and specifically the effects of genetic compatibility on mate choice and offspring viability. Genetic compatibility has been previously linked to the effects of specific genes of large effect, such as the major histocompatibility complex (MHC). MHC heterozygosity improves resistance to pathogens (Hedrick, 2002) and mating preferences have been shown to increase offspring MHC heterozygosity (Penn & Potts, 1999). In broader terms, genetic compatibility has been linked to overall genetic relatedness between mates and/or populations. At one extreme, inbreeding effects between closely related mates can reduce the fitness of offspring through the loss of heterozygosity and expression of deleterious recessive alleles (Lynch & Walsh, 1998). At the other extreme, outbreeding effects between distantly related mates can reduce the fitness of offspring through genetic incompatibility and disruption of co-adapted gene complexes (Lynch, 1991). When observed as a continuum with inbreeding and outbreeding as the extremes, the effects are expected to produce a function where the highest fitness occurs at intermediate levels of genetic relatedness between mates (Figure 1). A stronger understanding of this relationship is of interest to evolutionary biologists, and can provide practical information about optimal relatedness levels that can be used to guide conservation and agriculture programs that aim to rescue or enhance inbred populations via outbreeding.

Rachel Chambers: Plants on the edge: functional traits and grassland gradients

Rachel ChambersIt 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, that are bordered by active agricultural fields and forest fragments in Norfolk County.  I will quantify plant diversity and soil faunal diversity at varying distances from grassland borders, in association with environmental variables and functional traits. This research could inform restoration processes through determination of patch size as influenced by land cover. The use of plant and faunal functional traits could provide new perspectives for restoration initiatives.

November 13, 2015

Yeritza Bohoquez Ruiz: Evaluating the effects of root exudates from buckwheat, Fagopyrum esculentum,on Agriotes sputator larvae.

WirewormScott/McNeil group
Generalist insect herbivores utilise visual, chemical and tactile cues to locate host plants. However, generalist soil-dwelling herbivores rely most on chemical cues in order to detect suitable and avoid unsuitable plants. Wireworms (Coleoptera: Elateridae) are generalists and are serious pests of many agricultural crops; thus requiring pest management strategies. Preliminary studies observed reduced wireworm densities (genus Agriotes) after buckwheat (Fagopyrum esculentum) is used as a cover crop; potentially due to the plant releasing repellent, antifeedant and/or toxic chemicals into the soil. I will explore the different potential effects of chemicals from buckwheat roots on wireworm behaviour, using a six arm olfactometer and small plot experiments.  My results will be the basis for subsequent chemical analyses, as these compounds could offer an alternate management strategy.

Pria Mahabir: Identifying the neural mechanisms underlying female receptivity in drosophila

Drosophila brainMoehring group
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, yet females are the primary discerners of reproductive receptivity in most species. In order to address the existing knowledge gap we will be utilizing a combination of genetic tools, including temperature-sensitive gene disruption, in both Drosophila melanogaster and Drosophila simulans to isolate regions of the brain responsible for female receptivity or rejection. We will then assess the contribution of these neural region(s) to behaviour in the context of three candidate genes that have previously been identified as contributing to female mate preference in order to assess whether each gene acts via the same neural region. Identifying the neural basis of female receptivity, while of interest in its own right, will also contribute to our understanding of how neuronal circuits integrate multiple sources of information from various modalities to subsequently produce directed behavior