Western University BiologyWestern Science

Friday Philosophicals - Winter Semester 2017

Mikhail Mack:  Methylmercury in two northern peatland types and William Laur: Novel Trap Crop Design: Trichoplusia ni (Hübner) Attraction to Transgenic Solanum lycopersicum (L) Using Stable Hydrogen Isotopes To Study Migration In Pseudaletia unipuncta (Haworth)

Mikhail Mack: Methylmercury in two northern peatland types.
William Laur: Novel Trap Crop Design: Trichoplusia ni (Hübner) Attraction to Transgenic Solanum lycopersicum (L)

April 7, 2017

Mikhail Mack: Methylmercury in two northern peatland types

Mikhail Mack photoSupervisor: Dr. Brian Branfireun

Northern fen peatlands provide conditions favourable for sulphate reducing bacteria, largely responsible for producing methylmercury, an aquatic pollutant. Observations from a moss-dominated poor fen and sedge-dominated intermediate fen were used to compare spatial and temporal patterns of methylmercury production to assess if contrasting plant communities and nutrients control production. First, comparisons of methylmercury and porewater solutes were measured across two northern Ontario fens. Greater sulphate availability and lower pH in the poor fen resulted in greater methylmercury production. Second, riparian margins in the intermediate fen were evaluate to see if groundwater nutrient supply controlled methylmercury production and transport. Water table fluctuations rather than groundwater supply controlled sulphate availability and methylmercury production. The proximity of riparian margins to stream waters facilitated methylmercury transport to surface waters.

William Laur: Novel Trap Crop Design: Trichoplusia ni (Hübner) Attraction to Transgenic Solanum lycopersicum (L)

William Laur photoSupervisors: Dr. Ian Scott and Dr. Jeremy N. McNeil

New pest management strategies are required to counter the rise of insecticide-resistance in populations of greenhouse pest insects, for example Trichoplusia ni (Hübner), the cabbage looper moth. One alternative is to use trap crops - planting attractive, disposable plants within the main crop arrangement to draw pests away from the crop of interest. Transgenic Solanum lycopersicum (L) tomato lines were modified to over-express the gene that regulates carotenoid cleavage dioxygenase 1 (LeCCD1) enzymes resulting in altered production of tomato volatiles. The objectives of this study were to assess the attraction of cabbage looper moths to volatiles emitted by transgenic tomato lines relative to wild-type, as well as to determine if the response was modified post-oviposition for the purpose designing a novel trap crop.

March 31, 2017

Lucas Silveira: The major histocompatibility complex and mate choice in bluegill

Lucas Silveira photoSupervisor: Dr. 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 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 are being investigated using next gen sequencing techniques.

Kyle Doward: Where Do Ontario True Army Worms Come From? Using Stable Hydrogen Isotopes To Study Migration In Pseudaletia unipuncta (Haworth)

Kyle Doward photoSupervisors: Dr. Keith A. Hobson and Dr. Jeremy N. McNeil

The true armyworm (Pseudaletia unipuncta), a seasonal migrant, does not overwinter in Canada and I undertook experiments to determine if continental spatial hydrologic scales for deuterium (δ2H) in precipitation could help determine the natal origin of immigrants. Initially I established the relationship between water and wing chitin δ2H by rearing larvae on vegetation treated with different concentrations of deuterated water. I then analyzed the wings of 2016 field-collected moths captured during the three flight periods, testing the hypothesis that spring specimens (immigrants) would have a significantly different δ2H profile than summer (residents) and fall (emigrants) ones. The results indicate that spring moths originate from further south, and the preliminary inter year data suggest that 2008 and 2016 immigrants have similar geographic origins.

March 24, 2017

Joel Slade: MHC-mediated mate choice, and chemical and acoustic signaling of MHC genotype, in song sparrows (Melospiza melodia)

Joel Slade photoSupervisor: Dr. Beth MacDougall-Shackleton

Genes of the major histocompatibility complex (MHC) play a fundamental role in vertebrate immunity. Because selection at MHC often favors particular alleles and allelic combinations, assessing MHC profiles of potential mates should be advantageous. Additonally, in songbirds, candidate signals of MHC remain largely unexplored but may include odor cues from feather preen oil or the content of geographically variable song. Here, I present results on whether specific combinations of MHC alleles confer protection against avian malaria, using song sparrows (Melospiza melodia) as a model species. I will also discuss whether chemical composition of preen oil and song repertoire content reflect song sparrow MHC genotypes.

Jessica Deakin: Behavioural mechanisms of protandry in a migratory songbird

Jessica Deakin photoSupervisors: Dr. Yolanda Morbey and Dr. Christopher Guglielmo

The sex-specific mechanisms underlying protandry, the earlier arrival of males than females to breeding sites, are unknown for most species. Nocturnally migrating birds in cages will show periods of locomotor activity at night during migration periods (migratory restlessness), with the onset reflecting departure and intensity reflecting the migratory distance flown in wild conspecifics. Here, we tested the hypothesis that male black-throated blue warblers have earlier onset of spring migratory restlessness compared to females by using Noldus video analysis software to quantify nocturnal behaviour of birds kept in captivity. No sex-differences were found in the onset of migratory restlessness but males had higher intensity, represented as cumulative activity per night. This suggests that distance flown may be an important driver of protandry in this species.

March 17, 2017

Mathis Natvik: Contribution of Agronomic Grasses to Oak Recruitment Failure in Old Field Ecosystems

Mathis Natvik photoSupervisor: Dr. Hugh Henry

Oak populations in eastern North America are in steep decline and are being replaced by maples and walnuts. The mechanisms blocking oak recruitment in forests are well understood and include fire suppression, herbivore overpopulation, disease, and altered relationships with soil microorganisms. In contrast, the mechanisms blocking oak recruitment in old field ecosystems are poorly understood. In this study, we manipulate grass cover in old field settings to compare the effects of native grasses versus naturalized European grasses on oak recruitment. Preliminary results show that native oaks are very sensitive to the presence of Festuca rubra while European oaks are not. This European grass produces meta-Tyrosine, a potent allelochemical which European oaks may be tolerant of. The results are interpreted in the context of coevolution.

Kimberly Mitchell: Effects of a high-thiaminase diet on reproductive traits in three populations of Atlantic salmon

Kimberly Mitchell photoSupervisor: Dr. Bryan Neff

One potential obstacle to the reintroduction of Atlantic salmon in Lake Ontario is invasive prey fishes. These fishes contain high concentrations of the enzyme thiaminase, which breaks down the essential vitamin thiamine (B1). We compared the effect of dietary thiaminase on reproductive traits in three Atlantic salmon populations (LaHave, Lac Saint-Jean, Sebago), which have previously been used in reintroduction efforts. We hypothesized that a high-thiaminase diet would affect reproductive traits and these effects would differ among the three populations. To test our hypotheses, we performed experimental crosses with our low- and high-thiaminase treatment individuals within populations and measured reproductive traits. We present data on the effects of dietary thiaminase levels on mortality, yolk conversion efficiency, specific growth rate and sperm quality.

March 10, 2017

Julia Palozzi: Peatland plant-soil feedbacks dictate ecosystem properties and processes

Julia Palozzi photoSupervisor: Dr. Dr. Zoë Lindo

In Boreal peatlands, where aboveground plants literally become belowground soil, there is great opportunity for strong plant-soil relationships to arise. Boreal peatlands are important ecosystems due to high carbon sequestration and slow decomposition driven by cool and moist conditions and nutrient-poor plants. My research explores the intimate linkage between aboveground and belowground that shapes peatland properties and dictates decompositional processes. In an observational study, I show how plant-soil feedbacks between plant traits of the dominant ecosystem engineer and the peat environment drive ‘slow’ or ‘fast’ cycles that characterise two peatland types. In those same peatlands, through a reciprocal transplant using plant litter of two dominant plants I show that plant litter was decomposed more efficiently at its site of origin consistent with a home-field advantage.

Matheus Sanita Lima: Unravelling organelle genome transcription using RNA-sequencing data

Matheus Sanita Lima photoSupervisor: Dr. David Roy Smith

Organelle genomes are the most sequenced type of chromosome. Next generation sequencing (NGS) has been generating unprecedented amounts of genomic and transcriptomic data that are publicly available, but underused to investigate organelle genome evolution - most of the NGS data is generated for the study of cell nucleus only. We employed this untapped data source to investigate the transcription of organelle genomes in plastid-bearing protists. We mapped RNA-seq reads over 116 protists' mitochondrial and plastid genomes; 77 out of 116 species had their organelle genomes nearly entirely (> 85%) recovered from transcripts despite of the amount of non-coding DNA (intergenic regions and introns) they had. Therefore, polycistronic and/or pervasive transcription seemed to be the norm, regardless the genome structure. In this talk, I will show how publicly available RNA-seq data can be used to investigate organelle genome transcription and argue how current technologies are being underused to characterize organelle genomes.

March 3, 2017

Helen Chen: Assessing landscape effects on genetics and dispersal of the Rocky Mountain Apollo Butterfly (Parnassius smintheus) using a resistance mapping approach

Helen Chen photoSupervisor: Dr. Nusha Keyghobadi

The effect land cover has on dispersal is a key question in landscape ecology and it is important to understand just how well genetic variables and dispersal correspond. I compare the relationships of dispersal and population genetic structure using a resistance mapping approach. I analyze genetic and dispersal data from populations of the butterfly Parnassius smintheus, on Jumpingpound Ridge in Kananaskis. I use a resistance surface map of the study area generated in ArcGIS. This surface is analyzed in Circuitscape to derive resistance distances between butterfly habitats that will be correlated separately with historical mark-recapture dispersal and genetic data from this landscape. With a better understanding of how resistance surfaces reflect dispersal and genetic differentiation, we can better interpret the results of landscape genetic studies.

Lauren Witterick: Assessing the long term effects of perceived predation risk on the avian brain

Lauren Witterick photoSupervisors: 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. Using auditory playbacks to manipulate perceived predation risk in black-capped chickadees (Poecile atricapillus) in acoustic isolation and brown-headed cowbirds (Molothrus ater) in large outdoor aviaries, I found short and long term behavioural changes in individuals exposed to increased predation risk. My research connects laboratory methods used to quantify the effects of fear in the brain with behavioural changes found from perceived predation risk in the field.

February 17, 2017

Carlos Barreto: Factors affecting food webs and ecosystem processes in soil systems

Carlos Barreto photoSupervisor: Dr. Zoe Lindo

Food webs are important conceptual tools for illustrating feeding relationships among species, revealing energy flow, diversity and community structure. Although decomposition, nutrient cycling and carbon sequestration are processes happening in below ground environments, soil food webs are understudied compared to above ground terrestrial or aquatic systems. In addition, the ecosystem level processes of soil systems as emergent properties of soil food webs are affected by global change. My research will examine how soil food webs and ecosystem processes respond to increasing temperature, nutrients, atmospheric CO2 concentration and predator addition. I will perform both lab experiments using mesocosms as well as field experiments.

Nicole Zathey: Thermal performance of Atlantic salmon (Salmo salar).

Nicole Zathey photoSupervisors: Dr. Bryan Neff

Atlantic salmon (Salmo salar) were once abundant in Lake Ontario but were extirpated by 1900. Recent stocking programs have had low success, possibly because of a mismatch between the thermal environment in Lake Ontario and the thermal performance of the stocked salmon. Thermal performance curves (TPC’s) describe the effect of temperature on biological processes, and can be a useful tool for understanding the fitness of animals in different thermal environments. My thesis will use TPC’s to examine three metrics of performance in Atlantic salmon: burst swim speed, feeding rate and heart rate. I will compare these metrics across three populations and two rearing temperatures and explore the relationship between these metrics and thermal preferences. Together these data will be used to inform stocking programs.

February 10, 2017

Mathew Stefan: Parasites and divergence at the major histocompatibility complex (MHC) between the foraging ecomorphs of pumpkinseed sunfish (Lepomis gibbosus)

Mathew Stefan photoSupervisor: Dr. Bryan Neff

Disruptive natural selection related to foraging tactics has been recognized as a key factor to the initial stages of species divergence within populations. Pumpkinseed sunfish (Lepomis gibbosus) provide an excellent study system for disruptive selection, as resource-mediated intraspecific competition has been shown to drive divergence between foraging ecomorphs (subset of individuals within populations that that have distinct ecological diet and morphological features). This variation in feeding ecology may lead the ecomorphs to be exposed to different parasites. In theory, variation in parasite communities in different foraging habitats may drive divergent selection on hosts and may promote speciation. I will use pumpkinseed sunfish to examine the role of parasites on MHC and test whether these differences in parasite communities have caused divergent MHC genotypes between pumpkinseed ecomorphs.

Christian Therrien: The effect of shelter availability on diel activity and space use in three populations of Atlantic salmon (Salmo salar).

Christian Therrien photoSupervisors: Dr. Yolanda Morbey and Dr. Bryan Neff

Throughout their lifetimes, juvenile Atlantic salmon (Salmo salar) are under constant threat from predators and have thus evolved several predator avoidance behaviors, such as utilizing shelters. Despite shelter use being an important behavior against predation risk, how shelter availability modifies this behavior has been understudied and represents a management gap in the conservation of stream fishes. My research aims to examine how shelter availability affects the activity timing of Atlantic salmon and to examine if there are population differences in this behavior. I will be observing the behavior of juvenile Atlantic salmon from three populations held in net pens in a natural creek to determine how high and low shelter conditions influence juvenile behavior.

February 3, 2017

Jackson Kusack: Effects of agricultural intensity on reproductive success of Barn Swallows (Hirundo rustica).

Jackson Kusack photoSupervisor: Dr. Keith Hobson

Avian species breeding within agricultural landscapes have experienced declines worldwide. Studies have shown a linkage to increasing agricultural intensification which may influence prey insects. Nestling body condition is an important predictor of survival and is directly related to diet. Barn Swallows (Hirundo rustica) are a threatened, agriculturally associated, aerial insectivore species which makes them highly reliant on prey insects. My research aims to examine reproductive success in Barn Swallows breeding in a diverse landscape, focusing on the effects of nestling diet. I will sample breeding colonies that vary in degree of agricultural intensity, measuring nestling diet via DNA barcoding of fecal samples and stable isotopic analysis. This information will further our understanding of the mechanisms resulting in observed declines of a threatened aerial insectivore species.

Veerta Singh: Geographic variation in growth and toxicity of the fish-killing Raphidophyte, Heterosigma akashiwo

Veerta Singh photoSupervisor: Dr. Charles Trick

The complex interaction between factors, such as increased eutrophication, temperature and salinity, may help explain harmful algal bloom (HAB) prevalence. Heterosigma akashiwo is a prominent marine species that episodically forms HABs. H. akashiwo is a microscopic alga of the class Raphidophyceae, aptly named for causing red tides in coastal waters. It has been indicted for extensive fish mortality resulting in major economic losses for commercial fishing and aquaculture industries. Management of H. akashiwo blooms is challenging as the cause of toxicity is unclear. I will be comparing the growth and toxicity of different strains of H. akashiwo. My research aims to compare the growth and toxicity between strains of H. akashiwo, isolated from different geographic locations, under a suite of temperature and salinity regimes.

January 27, 2017

Renée Howard: Wetland restoration success evaluated through plant functional traits.

Renée Howard photoSupervisor: Dr. Irena Creed

Wetland restoration has increased over the last few decades as the importance of wetlands on the landscape has been recognized for their role in flood abatement, carbon sequestration, and habitat provisioning. Research suggests that vegetation structure might not be the best determination of restoration success. Rather, a functional look a plant communities through plant functional traits, has been suggested as a better method for evaluating wetland restorations and may provide insight into the functional recovery of wetland systems. My research aims to analyse plant functional traits of a wetland restoration chronosequence to understand how ecosystem processes change with time since restoration.

Joshua Isaacson: Katanin-60’s effect on female rejection of heterospecific males in Drosophila species.

Joshua Isaacson photoSupervisor: Dr. Amanda Moehring

An organism’s ability to recognize and mate only with conspecific individuals is vital to maximize their reproductive success and offspring’s fitness. I will study the genetic basis of mate recognition and female rejection behaviours by using two Drosophila species, Drosophila simulans (sim) and Drosophila melanogaster (mel). I will determine if katanin-60, a microtubule-severing protein, affects female rejection of heterospecifics. I will use the CRISPR/Cas9 system to produce hybrids that lack either the mel or sim allele to see if this results in mel-like or sim-like behavior. I will also use RNAi in conjunction with the UAS/Gal4 system to identify which brain regions contribute to female rejection behaviours. Understanding the genes affecting mate recognition and rejection would give us greater insight into how speciation occurs.

January 20, 2017

Dean Evans: Barn Swallow (Hirundo rustica) post-fledging movements and survival: an automated telemetry approach.

Dean Evans photoSupervisor: Dr. Keith Hobson

Due to the difficulty of tracking small birds, the post-fledging period is one of the least understood stages of the avian life cycle. This period also represents a time of strong selective pressure for juvenile migratory songbirds resulting in significant population bottlenecks. Barn Swallows (Hirundo rustica) are a threatened long distance migrant and little is known about the fate of juveniles once they leave the nest, especially in North America. Making use of automated radio telemetry (Motus), I hope to track the post-fledging survival and movements of juvenile Barn Swallows in Southern Ontario. The use of the existing Motus infrastructure in southern Ontario allows for a novel approach for measuring survival of this threatened species and provides the means for insight into their pre-migratory movements.

Spencer Heuchan: Plant stimuli-responsive “smart” biodegradable polymers for the use in timed release fertilizer coatings.

Spencer Heuchan photoSupervisors: Dr. Elizabeth Gillies & Dr. Hugh Henry

Asynchronies between fertilizer application and crop nutrient demand have led to over-fertilization and increased soil nitrogen leaching from agricultural fields. The use of stimuli-responsive biodegradable polymers for the coating of fertilizers offers a more targeted delivery mechanism, which could increase nutrient use efficiency and reduce soil nutrient losses. I have been working with a redefined class of triggable polymers (poly(ethyl glyoxylate)) that are designed to go through end-end depolymerization after the protective end cap on the polymer is cleaved off by a specific stimulus. I aim to develop an end cap that can be cleaved off by specific plant-root specific stimuli, which would allow for controlled and targeted release of fertilizer pellets.

January 13, 2017

Matthew Palumbo: Habitat selection and survival of adult female mallards in the Lake St. Clair region during autumn and winter.

Matthew Palumbo photoSupervisor: Dr. Scott Petrie Co-Supervisor: Dr. Christopher Guglielmo

Spatial and temporal use of habitats by animals is influenced by a variety of associated benefits and costs. The Lake St. Clair region provides a diversity of habitat management and conservation strategies that are ideal to investigate how waterfowl movements and foraging strategies vary in response to human disturbance (e.g., hunting), habitat quality, and food availability across the landscape. My objective was to evaluate resource selection of adult female mallards (Anas platyrhynchos) in relation to perceived risk and to determine if resource selection influences survival during autumn and winter. Preliminary results indicate that resource selection strategies of adult female mallards were influenced by the composition habitats categorized by land classification and ownership type while survival appears to be independent of these variables.

Andrew Beauchamp: Mechanisms underlying the timing of migration in White-throated Sparrows.

Andrew Beauchamp photoSupervisor: Dr. Yolanda Morbey & Dr. Chris Guglielmo

Seasonal migration is a common part of life for many North American bird species. Many of these species exhibit differential migration, where the spatial and temporal attributes of migration differ between groups of individuals within the same population. Differential migration is believed to result from multiple mechanisms, however the relative importance of these mechanisms is still uncertain. In this talk, I will discuss my upcoming research that will examine several mechanisms believed to influence migratory timing in birds. Using the White-throated Sparrow (Zonotrichia albicolis), a species known to display male-first differential migration, I will compare mechanisms between sexes and behaviourally distinct plumage morphs. These plumage morphs are genetically linked and allow for inferences regarding how the mechanisms underlying differential migration are effected by behaviour.

Friday Philosophicals run every Friday in The Kresge Building room 103 (KB 103) in the fall term. Seminars are at 3:30pm - 4:30pm.

Speaker Schedule Winter Term 2017

Jan. 13 Matthew Palumbo (E) Andrew Beauchamp (I)
Jan. 20 Dean Evans (I) Spencer Heuchan (I)
Jan. 27  Renée Howard (I) Joshua Isaacson (I)
Feb. 3 Jackson Kusak (I) Verta Singh (I)
Feb. 10 Mathew Stefan (I) Christian Therrien (I)
Feb. 17 Carlos Barreto (I) Nicole Zathey (I)
Mar. 3 Helen Chen (E) Lauren Witterick (E)
Mar. 10 Julia Palozzi (E) Matheus Sanita Lima (E)
Mar. 17 Mathis Natvik (E) Kimberly Mitchell (E)
Mar. 24 Joel Slade (E) Jessica Deakin (E)
Mar. 31 Lucas Silveira (E) Kyle Doward (E)
Apr. 7 Mikhail Mack (E) William Laur (E)
I = Introductory Seminar, E = Exit Seminar