Western University BiologyWestern Science

Archived Friday Philosophicals Abstracts - Winter Semester 2012

March 23, 2012 - A Friday Extra-Philosophical

March 16, 2012

Nahed Mahrous: Characterization of Corn Rhizosphere (Zea mays) Grown in Metal-contaminated Soil

Nahed Mahrous Philosophical

Supervisors: Dr. Gordon Southam and Dr. Sheila Macfie
Degree: M.Sc. Candidate

When plant roots grow into the soil, they create a rhizosphere. The release of plant metabolites promotes the growth of microorganisms within the rhizosphere, where they in turn alter the geochemical environment through the release of their metabolic products. The microorganisms can also increase the solubilisation of essential nutrients and some symbiotic organisms can promote metal tolerance. This interaction among plant roots and microorganisms shifts to change the physiochemical and biological soil properties. My project investigates the effects of a rhizosphere on metal bioavailability and microbial activity in a metal-polluted soil. The results suggest that metal bioavailability and microbial activity were higher within the rhizoshere, which was reflected by the decrease in the pH, while the microbial diversity was not affected by the growth of plant.

Ashley Warnock: Exposure of mercury of small-bodied fish in the Hudson Bay Lowlands

Ashley Warnock Philosophical

Supervisor: Dr. Brian Branfireun
Degree: M.Sc. Candidate

There is considerable interest in the mercury dynamics of the peatland-dominated watersheds of Canada’s Hudson Bay Lowlands in light of current and future climate and land-use changes. Little data exist on mercury (THg and MeHg) concentrated in the various abiotic and biotic components of the lotic ecosystems of the region, making assessments of future changes to Hg cycling difficult. As part of an ongoing monitoring program at the DeBeers Victor Mine near Attawapiskat, Ontario, small-bodied fish have been collected annually since 2008 from first- and second-order tributaries. Analysis of this data shows evidence of within-species variability over a relatively small geographic region, confounding the concept of ‘reference’ or ‘unimpacted’ sampling locations and populations. This unprecedented dataset will generate a baseline understanding for the ongoing monitoring of Hg in the far north.

March 9, 2012

Lindsey Valliant: The effect of overwintering diet quality on initiation of spring breeding in northern Peromyscus maniculatus

Lindsey Valliant Philosophical

Supervisor: Dr. Jack Millar
Degree: M.Sc. Candidate

There is variation in the mean breeding initiation date of Peromyscus maniculatus populations among years and the reason for this is unknown. In this study, carbon and nitrogen stable isotopes of hair of the deer mouse Peromyscus maniculatus were used to determine how overwintering diet quality varied among the years of 2004-2011. Then, the relationship of these yearly values was annual mean initiation of breeding date was examined. It has been found that mean hair carbon isotope values of adult P. maniculatus vary among years, which may be due to a yearly climatic effect on plant sources. Adult mean nitrogen isotope values did not vary among years. Adult 13C and 15N values do not appear to be correlated with initiation of breeding dates.

Chelsea Hicks: Persistent organic pollutants and metals in Lake Naivasha, Kenya: Contaminant movement and implications for human health

Chelsea Hicks Philosophical

Supervisor: Dr. Charles Trick
Degree: M.Sc. Candidate

The community in Naivasha, Kenya, believes that environmental contaminants pose a risk to their health. This concern stems from the massive increase in agricultural activity, industry and urban centers in Naivasha over the past 3 decades. All 3 of these human activities are often correlated with increasing levels of contamination by harmful chemicals, such as persistent organic pollutants and metals. My study explores the distribution of these contaminants in Naivasha’s sediment and dust and the potential risk that exposure poses to human health.

March 2, 2012

Rachel Hamilton: Monitoring Migratory Bat Activity along Landscape Features

Rachel Hamilton Philosophical

Supervisor: Dr. Brock Fenton
Degree: M.Sc. Candidate

Little is known about migratory bat movement across the landscape, however, studies suggest that linear geographical features may be important navigational markers during migration. My study explored activity patterns of migratory bats along north-south oriented landscape features in southwestern Ontario. Acoustic monitoring was used to indicate bat activity for two species, L.Cinereus and L. Borealis, at ridge and shoreline features. The levels of bat activity in relation to landscape features may indicate areas of significance for migratory bats during their annual seasonal movements and may also inform the placement of future wind turbines.

Katie Millette: The influence of habitat composition and configuration on the genetic structure of the pitcher plant midge

Katie Millette

Supervisor: Dr. Nusha Keyghobadi
Degree: M.Sc. Candidate

A fundamental goal of landscape genetics is to understand how landscape structure influences gene flow. Little is known about how the composition and configuration of habitat in a landscape contributes to patterns of genetic divergence. We investigate the relative contribution of landscape composition and configuration to patterns of genetic structure in the pitcher plant midge, Metriocnemus knabi, across spatial scales. As a larval inhabitant of the pitcher plant, the habitat of M. knabi is defined and organized among pitcher leaves, plants, clusters, and bogs. Using the amount of habitat, the size of habitat patches, and the degree of isolation among habitat patches as metrics of landscape composition and configuration, and hierarchical F-statistics as metrics of genetic structure, we examine this key question in landscape genetics.

February 17, 2012

Jennifer McDonald: The evolution of fruit body morphology within the Resupinateae

Jennifer McDonald Philosophical

Supervisor: Dr. Greg Thorn
Degree: Ph.D. Candidate

The evolution of reduced fruit body morphology (“cyphelloidism”) in the mushroom fungi is poorly studied and understood, especially within the Resupinateae. How many times has the cyphelloid habit evolved within the group? Do all cyphelloid members that are treated in this group belong? Are there other species of cyphelloid fungi treated in other genera that belong within the Resupinateae? I will present a preliminary phylogeny of the cyphelloid and lamellate members of the Resupinateae based on rDNA sequences to illustrate the evolution of the reduced basidiomata. For morphological studies, the few herbarium specimens associated with many species names may lead to false impressions of geographic range. In contrast, some previously suggested synonymies and reports based on misidentifications mask genuine patterns of geographic range.

Trinh Nguyen: Postmating Sexual Selection in Drosophila

Trinh Nguyen Philosophical

Supervisor: Dr. Amanda Moehring
Degree: Ph.D. Candidate

Although the costs of mating to females are high, females of many species are polyandrous. The benefits females receive from mating with multiple males must counteract costs. Polyandrous females can impose selection on males through mechanisms of postmating sexual selection. Postmating sexual selection is an important evolutionary force that can change allele frequencies within a population and drive sexual selection, and can also create divergence between populations that can eventually lead to speciation. My research will study postmating sexual selection at the molecular, cellular, and organism level using Drosophila as a model. The broad goal is to tease apart the antagonistic postmating sexual selection relationship between females and males.

February 10, 2012

Justin P. Saindon: How much gene flow is required to impede adaptation at a species range-edge? An artificial selection Drosophila model

Justin P Saindon Philosophical

Supervisor: Dr. Brent J. Sinclair
Degree: M.Sc. Candidate

Climate change is rapidly altering abiotic conditions at species range-edges and many organisms will have to shift their geographic ranges to accommodate the new conditions. However, gene flow can limit a species’ range by swamping the ability of a species to adapt to local conditions. An estimate of the amount of gene flow required to inhibit local adaptation has not been experimentally investigated. I use laboratory populations of Drosophila melanogaster under selection for desiccation resistance and quantify adaptation, as well as the physiological response to selection, in range-edge populations subject to migration from the core population. Preliminary results indicate my methods of selection were successful, but there was no response of gene flow on adaptation as measured by survivorship to the selection pressure.

February 3, 2012

Colin Hayward: Ecological implications of stomach specialization: a comparison of Jamaican fruit eating bats

Colin Hayward Philosophical

Supervisor: Dr. Brock Fenton
Degree: M.Sc. Candidate

Specialized stomach morphology can lead to important consequences in the dietary strategies of frugivorous animals. Food passage times and dietary selection are two such characteristics determined by these adaptations. This can easily be observed in sympatric New World leaf-nosed bats such as Ariteus flavescens, Artibeus jamaicensis, and Glossophaga soricina. Although these species all eat fruit, they exhibit different stomach morphologies and dietary strategies. Ariteus flavescens, a very poorly understood endemic Jamaican species, purportedly has skeletal muscle in its stomach walls leading to a unique feature within the mammalian class. Through fecal analysis and feeding experiments I will examine the food passage times relative to the diet and roosting preference of each species to determine the biological and ecological implications of each strategy.

Helene LeVasseur: Viens Evaluating the morphological factors that affect mating success

Helene LeVasseur Philosophical

Supervisor: Dr. Amanda Moehring
Degree: M.Sc. Candidate

The lock and key model has long been used as an explanation for highly divergent male genitalia in sister species. Although it initially seems intuitive, much controversy surrounds the model as it is difficult to test. The sibling species Drosophilia simulans and D. mauritiana have long been suspected to be a prime example of the lock and key model as the only apparent morphological difference between them is the male genital arch, but little evidence has been previously reported on its validity. The purpose of my study is to investigate what role morphological factors play on the reproductive isolation of these two species, therefore determining if the lock and key model is a viable explanation for species isolation.

January 27, 2012

Kaylin Liznick: Changes in sediment inputs and trophic status and their relation to mercury bioaccumulation in Lake Erie, Ontario

Kaylin Liznick Philosophical

Supervisor: Dr. Brian Branfireun
Degree: M.Sc. Candidate

Regional atmospheric mercury emissions have been declining since the late 1970s, and although organismal concentrations of mercury are expected to decrease concurrently, the bioavailability of mercury in some areas is complicated by many factors. Continuing research in one such area, Lake Erie, has revealed a recent (post-1990) rising of mercury concentrations in its top predatory fish. The purpose of my study is to examine the trophic changes in the lake resulting from introduced benthic invasive species, determining the role they play in mercury bioaccumulation in higher organisms. I will also be monitoring mercury levels in biotic and abiotic samples after storm and sediment re-suspension events to determine the role of these occurrences in lake-wide mercury cycling.

Leslie Erdman: The effect of trophic level on stable hydrogen isotope ratios in bat fur

Leslie Erdman Philosophical

Supervisor: Dr. Brock Fenton
Co-supervisor: Dr. Fred Longstaffe
Degree: M.Sc. Candidate

Stable isotope analysis has become an important tool to study bat ecology. Stable hydrogen isotope ratios (δD) in particular can be very useful for determining if migration occurs and if so, at what distance bats migrate. Little is known, however, about the effect of trophic level on δD values in bat fur. Understanding the effect of trophic level on δD variation can help to refine our understanding of migration in bats as well as provide additional information about their diets. I will conduct stable isotope analyses on several bat species, both captive and wild, to determine if there is an effect of trophic level on the stable hydrogen isotope ratios in bat fur.

January 20, 2012

Bryana McWhirter: The Interactive Effects of Warming and Nitrogen Deposition on Tree Establishment in Temperate Old Fields

Bryana McWhirter Philosophical

Supervisor: Dr. Hugh Henry
Degree: M.Sc. Candidate

Old field habitats are increasing as areas previously utilized for agricultural production have been abandoned or converted into naturalized areas. With time and lack of disturbance, old fields develop into secondary forest communities. However, there is concern that predicted global changes in climate and nutrient deposition will alter the composition and dynamics of plant communities. Specifically, increases in temperature and nitrogen deposition may have an impact on the ability of woody species to germinate and compete with established grasses in old field environments. In this study, I will be examining the effects of increased temperature and nitrogen deposition on the survival, growth, and competitive ability of several early successional species commonly found in temperate old fields.

January 13, 2012

Philip Wilson: Movement patterns and habitat selection by Long - tailed Ducks (Clangula hyemalis) overwintering at Lake Ontario , Ontario

Philip Wilson Philosophical

Supervisor: Dr. Scott Petrie
Degree: M.Sc. Candidate

Decisions to develop offshore areas of the Great Lakes with industrial wind turbines were preceded without adequate research on impacts to animal movements and migration. Planned development of industrial wind turbines throughout the lower Great Lakes may affect overwintering sea duck populations because of their placement in areas where ducks may forage and roost during winter. Movement patterns and habitat selection by animals are used to infer resource patch availability, habitat quality, estimate minimum space requirements, and evaluate the plasticity of individuals to habitat change. Long-tailed Ducks (Clangula hyemalis), the most abundant sea duck overwintering at Lake Ontario, will be implanted with satellite transmitters to investigate environmental variables hypothesized to influence movement patterns and habitat selection in the nearshore and offshore habitats of Lake Ontario.

Michael Thorn: Chinook Salmon (Oncorhynchus tshawytscha) Early Life History Survival within Three Great Lakes Tributaries

Michael Thorn Philosophical

Supervisor: Dr. Yolanda Morbey
Degree: M.Sc. Candidate

Chinook salmon (Oncorhynchus tshawytscha) were first successfully introduced to the Great Lakes in the 1960’s. Since then, Chinook have colonized tributaries throughout the Great Lakes with variable success resulting in differential rates of fish production. The early life history (egg deposition-emergence) of Chinook salmon is associated with high mortality rates and can significantly influence fish recruitment rates. The Nottawasaga River, Sydenham River (both in Lake Huron), and Credit River (Lake Ontario) have very different recruitment rates and little is known about the underlying factors contributing to this difference. The purpose of my study is to investigate how maternal traits, egg quality, habitat quality and habitat quantity affect early life history survival in Chinook salmon and how this influences tributary recruitment rates in the Great Lakes.