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Friday Philosophicals - Fall Semester 2020

Friday Philosophicals with Pok Man Paul Wan and Jacob Lasci

Garth Casbourn: The role of testosterone in regulating the movement behaviours of juvenile migrant songbirds Rebecca Howe: Effects of experimental malaria infection on migration of Yellow-rumped Warblers (Setophaga coronata).

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

Each week a Zoom invite will be distributed to bioseminar-ee@uwo.ca. Contact ymorbey@uwo.ca if you are not on this list and need the Zoom login details.

December 11, 2020

Garth Casbourn: The role of testosterone in regulating the movement behaviours of juvenile migrant songbirds

Garth Casbourn photoSupervisor: Dr. Scott MacDougall-Shackleton

The post-fledging period is a critical stage in the life of a juvenile migrant songbird. Juveniles must develop their foraging skills, as well as the flight, navigation, and orientation skills that will allow them to make their first migration. Movement across the landscape is critical to developing all of these skills, and there is likely individual variation in the propensity to move. Testosterone is related to individual differences in migration distance in adult sparrows, but it has not been studied in the context of other movement behaviours. I investigated the relationships among movement propensity in a novel environment, juvenile prospecting movements, and testosterone profile in juvenile Song Sparrows (Melospiza melodia). I characterized testosterone profile as the maximal level of circulating testosterone produced in response to an injection of GnRH. I introduced fledged, free-living juvenile birds to an artificial chamber (2.4 x 2.4 x 1.8 m) containing 5 artificial trees, and recorded activity for 10 minutes as an index of exploration behaviour. Finally, I handtracked radiotagged birds for 2-4 weeks to assess prospecting movements. I present my findings on the correlations between these behavioural and physiological phenotypes.

Rebecca Howe: Effects of experimental malaria infection on migration of Yellow-rumped Warblers (Setophaga coronata)

Rebecca Howe photoSupervisors: Drs. Chris Guglielmo and Beth MacDougall-Shackleton

Avian migration between breeding and wintering grounds is an energy intensive behavior that requires birds to stop frequently to rest and refuel. These resting locations, called migratory stopovers, are where birds spend much of their migratory period. The duration spent at a stopover is based on a bird's condition upon arrival. Stopovers present the threat of exposure to novel pathogens or the spread of pathogens amongst birds, but the effect that infection has on migration is not well studied. During fall migration 40 Yellow-rumped Warblers were brought into captivity and inoculated with avian malaria (Plasmodium cathemarium) to simulate infection at a migratory stopover. Avian malaria is a common unicellular bloodborne protozoan parasite that effects 68% of wild bird species and chronically effects at least 50% of Yellow-rumped Warblers in the study area. Twelve days after inoculation birds were released further south along their migration route and monitored. Infection status, activity levels, and departure date are compared between treatments to determine if avian malaria exposure effects stopover and departure behavior. This experiment is a novel combination of inoculation and radio-tracking to simulate infection at a stopover and is an important addition to understanding migration.

December 04, 2020

Vonica Flear: The Q continuum: Effects of gene-environment interactions on the evolution of social behaviours

Vonica Flear photoSupervisor: Dr. Marc-André Lachance

Inclusive fitness models in sociobiology emphasize the importance of relatedness, R, and synergy, S when exploring the evolution of social behaviours. Very few models explicitly consider ‘role’, or environmental stimuli, influencing the expression of behaviours, and none consider genetic-environment interactions where genotype predisposes individuals to certain roles. I propose a third key variable for inclusive fitness models, Q, which describes the overlooked potential bias in the genetic composition of individuals exposed to an environmental stimulus – here referred to as ‘role’. I describe an inclusive fitness model built from Price’s formula which can be presented in a ‘Hamilton’s Rule’ format. I consider classic social behaviour models using this format, and find the inclusion of gene-environment interactions dramatically changes the original results. This, in conjunction with the increase in evidence supporting gene-environment interactions involved in eusocial caste determination, suggest that current inclusive fitness models may be missing key details about the evolution of social behaviours.

Jeff Martin: Cache-site selection by Canada jays (Perisoreus canadensis)

Jeff Martin photoSupervisors: Drs. David Sherry and Yolanda Morbey

At high latitudes extended winters often result in food scarce periods, presenting a significant challenge for non-migratory species. Food caching is a behavioural strategy employed by a wide variety of these species in an effort to mitigate the effects of food scarcity. Canada jays (Perisoreus canadensis), a non-migratory resident in Canada and parts of the United States, are one such species. Canada jays rely on cached food in order to survive winter, and thus, cached food items remaining viable and available when required is essential. Through a series of captive experiments, I investigated the ability of Canada jays to actively select and exploit caching locations that increase the likelihood their caches will remain viable upon recovery. I suggest that Canada jays are able to make accurate assessments about their environment and, in response, alter their caching behaviour to increase their chances at success.

November 27, 2020

Kevin Park: Characterizing a Genetic Basis of Dispersal and Recolonization in a Butterfly Metapopulation

Kevin Park photoSupervisor: Dr. Nusha Keyghobadi

Persistence of a metapopulation and local populations within it are dependent on the dynamic balance between local extinction and recolonization of habitat patches, in which dispersal, the movement and settlement of individuals from their native patch to another, serves as the key mechanism. Despite its importance, the genetic basis of metapopulation-level dispersal is poorly understood, especially in natural systems. In my study, I will utilize the effects of local extinction and removal events on the genetic structure of local populations to characterise a genetic basis of dispersal and recolonization in Parnassius smintheus, an Apollo butterfly species that inhabit meadow patches in the Rocky Mountains. I will be focusing on a metabolism-related candidate locus - Phosphogluclose isomerase (Pgi), that has been associated with variation in movement abilities across several other insect species. I will genotype and assess the change in frequency of single nucleotide polymorphisms (SNP) within the Pgi locus, as well as other SNPs throughout the P. smintheus genome across historical extinction and removal events. I hypothesize that variation in Pgi underlies variation in dispersal in P. smintheus, and therefore predict that variations associated with increased dispersal ability or likelihood will increase in frequency within the local population following recolonization.

Dariusz Wojtaszek: Migratory connectivity of hunted northern pintails

Dariusz Wojtaszek photoSupervisors: Drs. Keith Hobson and Ben Rubin

Understanding migratory connectivity helps wildlife managers consider the conservation needs of migratory species throughout their annual life cycle and so facilitates long-term management plans. The Northern Pintail (Anas acuta) is a waterfowl species that suffered large population declines throughout the 1980s and remains below long-term management goals. Current research suggests that conversion of native habitat to agriculture, is limiting the recruitment and growth of the population. The objective of this thesis is to better understand the source of hunted Northern Pintails in North America, using intrinsic markers. Intrinsic markers are particularly useful because pintails have a large geographic range, and unlike extrinsic markers such as banding, is more inclusive of inaccessible areas and does not require recapture. I will use measurements of hydrogen ratios (δ2H) feathers from hunted pintails throughout North America to assign individuals to probable origins. Then, I will use carbon and nitrogen stable isotope ratios (δ13C, δ15N) and corticosterone levels in feathers to infer habitat and individual condition. I expect to see lower values of δ13C, δ15N and feather corticosterone in areas further north, as assigned by δ2H. These findings can be used by wildlife managers to inform bag-limits, restrictive hunting seasons and adaptive harvest management.

November 13, 2020

Colleen Wardlaw: Investigating microplastic ingestion in demersal fishes from the Thames River, ON.

Colleen Wardlaw photoSupervisors: Drs. Bryan Neff and Patricia Corcoran

Microplastics (plastic particles <5 mm) are now ubiquitous in natural environments. Within rivers, the abundance of microplastics differs considerably among sites, but few studies have measured microplastics ingestion by freshwater fishes or the relationship between ingestion and local variation in microplastics abundance. I will collect two species of fishes white sucker (Catostomus commersonii) and common carp (Cyprinus carpio) from the Thames River (Ontario, Canada) at locations where microplastic levels in sediment have previously been characterized. The gastrointestinal tract of these fish will be extracted and digested to characterize the number and type of microplastics ingested by the fishes using Fourier-transform infrared spectroscopy (FT-IR). These data will be used to test the relationship between the abundance of microplastics in the sediment and their ingestion by fishes, and will contribute to a better understanding of the effects of plastic pollution in natural environments.

Erica Stroud: Short-term vs. long-term responses of soils to warming and nitrogen addition in a temperate old field

Erica Stroud photoSupervisor: Dr. Hugh A.L. Henry

Climate warming and atmospheric nitrogen deposition are two global change drivers predicted to affect the productivity and nutrient cycling of northern temperate grasslands over the next century. Previous studies investigating the effects of climate warming and nitrogen additions on soils in grass-dominated systems have typically been performed over a short time period (< 5 years), whereas long-term experiments (>10 years) are uncommon. The objective of this research is to compare the short- and long-term effects of warming and nitrogen deposition on soil carbon, nitrogen and extracellular enzyme activities in a field experiment located at a grass-dominated old field site in London, Ontario. Forty 1m2 plots have been receiving either warming or nitrogen fertilization treatments for 14 years and thirty new warming and nitrogen addition plots have been established to examine the short-term effects. Soil samples will be collected throughout the growing season, fractioned into heavy and light fractions of soil organic matter and analyzed using FTIR spectroscopy. Nitrate and ammonium concentrations, along with extracellular enzyme activities, will also be measured. This experiment will provide insight into whether the results of short-term global change studies can be extrapolated to longer-term effects on soil carbon, nitrogen, and microbial activities.

October 30, 2020

Tyler Watson: Investigating mycelial-plant biomass mat application to reduce early-colonizing weeds in row-crop agriculture

Tyler Watson photoSupervisor: Dr. Greg Thorn

Properties of mycelia such as density, hardiness, and adaptability have led to recent application in industrial forms. This project suggests this utility may extend to weed control in agriculture. I will determine if an application of a fungal-crop residue mat can function as an effective weed control as an alternative to traditional herbicide regimens in agriculture. I will determine candidate fungal species and correct slurry mixture for application. Following slurry application, I will investigate weed emergence through direct stalk counts, as well as effects on the crops or surrounding soil by measuring crop biomass at termination as well as soil pH and nutrient availability. This will be done initially in a controlled greenhouse setting, before expanding to agricultural field trials, more accurately replicating a real-world environment. If successful, this approach offers the opportunity to make a novel use of crop waste, simultaneous reducing costs and environmental impacts on current weed-reduction methods, providing both economic benefit and improved agricultural sustainability.

Noor Saeed Cheema: Manipulating the root mycobiome to improve plant performance and reduce pathogen pressure in corn (Zea mays)

Noor Saeed Cheema photoSupervisor: Dr. Greg Thorn

Crop rotation is a system where crops are rotated annually in consistent sequence. Commonly, local crop rotations often feature corn, soybeans, and wheat. These practices have been shown to effectively reduce pests, weeds, and disease cycles, while simultaneously increasing crop yield. Crop rotation effects the soil chemistry, and the soil microbes present. Manipulation of the micro- and myco-biomes could potentially reduce pathogen pressure and increase yield. However, the identification of an organism that can induce these effects must be determined first. In 10 farm fields in Southwestern Ontario, our industrial partner, A&L Biologicals, has confirmed historic yield differences in crops of the corn, soybean, and wheat rotation. From the 10 farm fields, root-associated fungi were identified from corn root samples by metabarcoding based on ribosomal DNA sequences, and a suite of fungi was isolated in culture and identified. The objective of my research is to investigate how selected fungal isolates affect plant performance, soil chemistry, and root mycobiome in corn (Zea mays). The ability to manipulate the mycobiome to improve crop health has potential agroecology applications.

You may find he Speakers List for the Winter Term 2021 here.