á Department of Biology Department of Biology Western University Science Logo

Friday Philosophicals - Winter Semester 2020

Friday Philosophical March 13-27 cancelled

Seminars are cancelled for the remainder of the term.

Friday Philosophicals run most Fridays in Kresge Building K103 (check the schedule). Seminars start at 3:30 pm and are expected to end by 4:20 pm.

March 13, 2020 CANCELLED

Samuel Rycroft: Freezing tolerance of herbaceous legumes in the northern temperate zone: are legumes disproportionately sensitive to freezing?

Samuel Rycroft photoSupervisor: Dr. Hugh Henry

In northern temperate regions, the effects of freezing stress from late Fall into early Spring can vary substantially among herbaceous (i.e. non-woody) plant species. Anecdotal evidence and previous research suggest herbaceous legumes (family: Fabaceae) are more freeze-sensitive/susceptible than other herbaceous functional plant groups. As legumes can increase soil nitrogen inputs through symbioses with rhizobia, this may have important implications for ecosystem nitrogen cycling in a changing climate. Though previous investigations have studied the effects of freezing on specific legume species, comparative studies on a variety of leguminous vs. non-leguminous species have been lacking. I have been using a combination of controlled environment (freezing treatments within controlled chambers) and field (increased freezing via snow removal) experiments to investigate the impacts of freezing stress on herbaceous legumes relative to other herbaceous species. This work can provide insight into species composition and nitrogen dynamics in temperate plant communities in a changing climate.

Shayla Kroeze: Conservation genetics of the endangered Mottled Duskywing (Erynnis martialis)

Shayla Kroeze photoSupervisor: Dr. Nusha Keyghobadi

Worldwide declines in insect species threaten a “catastrophic collapse of nature’s ecosystems”, and butterflies are experiencing one of the largest of these declines. Re-introducing species to areas where they once occurred is increasingly being used as a strategy for recovering at-risk populations. Early re-introductions of butterfly species were largely unsuccessful due to a lack of background research and rigorous protocols. I will characterize genetic diversity using microsatellites to inform planned re-introductions for the only endangered species of butterfly in Ontario, the Mottled Duskywing (Erynnis martialis). My work will form part of a larger, collaborative effort to achieve the overall recovery goal of the species in Ontario.

March 6, 2020

RoseLynne Savage: Exploring the diversity and specificity of zooplankton symbionts in coastal marine ecosystems

RoseLynne Savage photoSupervisor: Dr. Vera Tai

As primary consumers, zooplankton are a key link between primary producers and higher trophic levels in aquatic ecosystems. Understanding the dynamics of zooplankton productivity, especially in response to predation, is a critical area of current research. However, the influence of symbiotic relationships, including parasitism, on zooplankton production remains less understood. In particular, parasites of zooplankton have rarely been characterized and their impact on zooplankton health is largely unknown. Many zooplankton parasites are eukaryotic microorganisms, or protists. Using a metabarcoding approach, I am investigating the diversity of protist symbionts associated with marine crustacean zooplankton and determining the host-specificity of potentially parasitic lineages. I will be investigating the seasonal trends in microbiome composition of as well as between developmental life stages. This work provides insight into the composition and specificity of zooplankton symbionts in coastal ecosystems and contributes to resolving the ecological significance of zooplankton parasitism in marine food webs.

Lucas Khodaei: Understanding the genetic and neurological basis of larval aggression and co-operation in Drosophila melanogaster

Lucas Khodaei photoSupervisor: Dr. Amanda Moehring

Aggressive behaviours impact an organisms’ survival and fitness as individuals frequently must compete with others to acquire resources and conflict often results. To understand how aggression is modulated in Drosophila larvae, Lucas Khodaei will attempt to identify which genes and neurons induce aggression in larvae, whether there are sex differences in larval aggression, and if these behaviours are indicative of adult aggressive behaviours. Lucas will attempt to create a protocol for sexing 2nd instar larvae using GFP and RFP markers, and in Drosophila hyper aggressive lines, such as Bully flies, determine if certain genes and neurons such as the pC1/pC2 neuron clusters will also affect larvae in similar ways. Additionally, Lucas is interested in studying the relationship of aggression and how it might be linked to mating in relation to female receptivity or male rejection in Drosophila lines with varying levels of aggression using multiple DGRP fly line.

February 28, 2020

Scott Walters: The importance of biofilm fatty acids for migrating shorebirds

Scott Walters photoSupervisors: Drs. Chris Guglielmo & Keith Hobson

Migrating shorebirds refuel at stopover sites to power the energetically-expensive flight necessary to reach their breeding grounds. Biofilm produced on the surface of mudflats has been recently identified as a major component of shorebird diet during stopover, and fatty acid composition is hypothesized to be the key factor of this potentially critical food source. Samples will be collected from biofilm and Western Sandpipers (Calidris mauri) at mudflats in the Pacific Northwest of British Columbia and Washington State, USA during both spring and fall migrations. Compound-specific stable isotope analysis will determine how different biofilm fatty acids are routed and metabolized by migrating shorebirds. Subsequent feeding trials of captured shorebirds will determine their ability to synthesize important fatty acids, determining the importance of exogenous inputs. This understanding is particularly important in the face of increasing habitat alteration from development, such as plans to expand a shipping terminal near the Fraser River Delta.

Marianna Wallace: Root-inhabiting and rhizosphere mycobiomes and crop yield

Marianna Wallace photoSupervisor: Dr. Greg Thorn

The rhizosphere, the area of soil in direct proximity of plant roots, is a hot spot of microbial diversity and activity. While many members of the rhizosphere microbiome are beneficial to plant growth and can provide protective advantages, pathogenic microorganisms may break through the protective microbial shield and cause disease. The communities of microorganisms present in the rhizosphere soil, are thereby directly linked to plant health and crop yield. My research will focus on identifying the members of the mycobiome communities of rhizosphere and root of corn, soybean and wheat, which are planted in rotation on the same fields. I aim to profile the mycobiomes of low and high yield patches crops within fields by next-generation sequencing of the ITS region, in order to identify microorganisms providing protective or pathogenic effects for these crops. The knowledge gained through this research can be integrated into current soil health management systems to reduce crop losses.

February 14, 2020

Farhaan Kanji: Assessing the impact of biosolid-typical levels of imidazoles on soil fungi

Farhaan Kanji photoSupervisors: Drs. Edward Topp (AAFC) & Hugh Henry

In parallel to long-held concerns over the development of antibiotic resistance in bacteria due to residual antibiotics in the environment, concern over the development of antifungal resistance due to the persistence of antifungals in the environment is growing. Miconazole and clotrimazole are environmentally persistent pharmaceuticals that are typically found in over-the-counter topical creams used for treating yeast infections. To study the effects of these pharmaceuticals on soil fungi, microplots at AAFC-London have been annually amended with various levels of miconazole and clotrimazole since 2010 and fungal isolates from the soils have been tested for their sensitivities toward these drugs. This study aims to elucidate the effects that levels of miconazole and clotrimazole typical of a biosolid-amended agricultural soil plot have on changes in microbial composition and antifungal resistance, and more broadly apply the results of these experiments to address concerns over links between clinical antifungal resistance and environmental antifungal persistence.

William Laur: A multi-scale investigation of predator-prey interaction strength under warming

William Laur photoSupervisor: Dr. Zoë Lindo

Individual interactions contribute to the structure of a community. Predation, herbivory and competition have cumulative effects resulting in characteristic energetics at the population- and community-levels—changes to individual interactions would likely have consequences to population and community energy dynamics. A significant rise in global mean temperature is expected to increase the energy demands of earth’s inhabitants, altering trophic relationships between interacting organisms, and consequently affecting community consumer-resource abundance-size spectra. My dissertation will focus on the predator-prey consumer-resource interaction between individual soil invertebrates exposed to warming, as well as the resulting changes to the population and community energetic characteristics. Initially, a link will be drawn between predator consumptive pressure and optimal prey body-mass, providing a useful measure of interaction strength. Using this defined mass-interaction strength relationship, shifts in the abundance-size spectra under warming between predator-prey populations forming a community will be investigated in connection to community restructuring.

February 7, 2020

Andrew Pitek: Potential for probiotics to mitigate environmental stress in Western honey bees

Andrew Pitek photoSupervisor: Dr. Graham Thompson

The Western honey bee is an efficient and valuable pollinator of flowering crops in Southern Ontario. Despite its vital role in the agri-food sector, honey bees are proving difficult to sustain against multiple environmental stressors. The advent of the human microbiome initiative recognizes the importance of probiotics in sustaining life of various species. My research explores a potential for beneficial bacteria to augment bee health and bolster immunity against local parasites and pathogens. Specifically, I will test the efficacy of an oral and topical delivery of a probiotic formulation of Lactobacilli on bee resistance to two bacterial pathogens and one ectoparasitic mite. Findings at Western suggest that oral delivery of Lactobacilli can lower pathogen load of American foulbrood, but this effect is yet to be tested across the Ontario landscape. This seminar will explain my designed field and laboratory study that is highly relevant to the Ontario beekeeping community.

January 24, 2020

Breanna Craig: Long term vs. transient responses to warming and nitrogen addition in a temperate old field

Breanna Craig photoSupervisor: Dr. Hugh Henry

Climate warming globally is expected to intensify over the following decades; moreover, the intensity of this effect is expected to be greater at increasing latitudes. In many northern temperate regions, industrial and agricultural activities have increased over the last century, resulting in high rates of atmospheric nitrogen (N) deposition. These rates are projected to continue increasing worldwide through 2050 and could further drive changes in plant productivity, with important implications for global carbon cycling, and have detrimental effects on plant diversity as a result of terrestrial eutrophication. Both warming and atmospheric N deposition have been found to have an additive effect on increasing plant productivity. My research will be restarting a pre-existing 15 year old field experiment, in which I will compare the short-term (1-2 year) effects of warming via heaters and N fertilizer addition on plant productivity, relative species abundances and plant tissue N content compared to the long term (14-15 year) effects.

HaeWon Kim:Uncovering the impact of a cover crop on the insect-pest wireworm

HaeWon Kim photoSupervisor: Dr. Ian Scott (AAFC) & Dr. Hugh Henry

Cover crops are also known as service crops or companion crops and it is mainly grown to improve soil health. While the practice has been long established, its full value is only beginning to get understood. Traditionally, it was typically planted to reduce soil erosion, better retain nutrients and moisture, but recently, researches have shown that cover crops can be planted to suppress weeds and delay herbicide resistance. The area that is still relatively unexplored is the impact of cover crop on soil invertebrates, especially the soil insect pest. Studies from Eastern Canada reported that buckwheat plantation suppressed the soil insect pest, wireworm. The focus of my research is to assess if buckwheat can suppress wireworm species present in Ontario. My research also aims to elucidate the buckwheat mediated insect pest suppression. The knowledge gained through this research can be integrated into the current pest management system to suppress soil pest using a cultural method and thereby reduce pesticide input.

January 17, 2020

Emma Churchman: The endocrine and genetic regulation of adaptive parental care in sunfish

Emma Churchman photoSupervisor: Dr. Bryan Neff

Parents determine how much energy to invest in caring for their offspring based on perceived value of the brood. This value is often associated with the relatedness of the offspring and parent, which can be assessed through kin recognition. In this study I will test if male sunfish adjust their parental investment based on their perception of paternity by directly reducing their paternity though egg swaps between nests, or by providing a visual cue to the male that indicates an uncertainty of paternity. I propose hormones, including androgens and prolactin, and gene expression in key regions of the brain are important mechanisms regulating parental care. I predict males with lower perceived paternity will have lower circulating levels of androgens and prolactin and decreased expression of genes associated with parental care. By understanding the mechanisms involved in the response to kin recognition, we can further understand how parental care itself evolved.

Jack Goldman:Chemical communication in sunfish breeding systems

Jack Goldman photoSupervisor: Dr. Bryan Neff

Breeding systems characterized by alternative mating tactics have fascinated ecologists for decades. These systems are characterized by complex interactions between individuals, including the recognition of kin and mates. High rates of brood parasitism in these systems make it important to recognize kin vs. non-kin within a nest. Increased competition for access to mates emphasizes the value of mate recognition. Despite the adaptive importance of recognizing kin and mates, the sensory mechanism involved are poorly understand. Using bluegill and pumpkinseed sunfish as model systems, my research aims to elucidate how individuals use chemicals in kin and mate recognition, and to identify the active chemical compounds mediating these interactions.

January 10, 2020

Dong Lee: Metschnikowia mitochondria

Dong Lee photoSupervisors: Dr. David Smith & Dr. Marc-André Lachance

Our current understanding of mitochondrial genomes is biased toward metazoans, which represent the majority of sequenced mitochondrial DNAs. Yeast mitochondrial genomes are an appealing alternative to those of metazoans for studying genomic evolution and diversity due to their high diversity in size, shape and gene synteny. The genus Metschnikowia is known for producing two unique ascospores and living inside of guts of beetles. Currently there are 72 genomes belong to the large-spored subclade of this genus available on Genbank. These genomes, however, lack complete mitochondrial genomes. Therefore, mitochondrial genomes of 72 strains of large spored Metschnikowia species will be constructed and analyzed in detail, focusing on diversity in size, shape, and gene synteny to further our understanding of mitochondrial genome evolution. Also, intron rich genes cob and cox1 will be analyzed to provide new insights into evolution of introns.

Liam Brown: Resist! Investigating the response of the soil bacterial mobilome to long-term exposure of macrolide antibiotics.

Liam Brown photoSupervisors: Dr. Ed Topp (AAFC) & Dr. Vera Tai

Macrolide antibiotics have been identified as “critically important” by the World Health Organization because of their use as first-line and sole treatments of serious human infections, such as community-acquired pneumonia and campylobacteriosis. The extensive use of macrolides in healthcare and agriculture has led to increased drug resistance among historically susceptible bacterial species, and of particular concern is the possibility for these antibiotics to promote resistance in the environment via fertilization of agricultural soil with macrolide-contaminated manure or biosolids. To investigate if long-term exposure of agricultural soil to macrolides promotes resistance in environmental bacteria, soil microplots in London, ON were exposed annually to a mixture of three macrolide antibiotics, and an increase in several resistance genes was observed over time. The goal of my research is to investigate the role of mobile genetic elements in the dissemination of resistance genes in these soil bacteria using culture-based and next-generation sequencing methods.

Schedule for the Winter Term 2020

Date First Speaker Title Second Speaker Title
The remaining seminars for the term have been cancelled.

3 Apr.


EDI Workshop Lesley Oliver anti-oppression training: colonization, intersectionlity & microaggression), 2:30-4:30