Archived Friday Philosophicals abstracts- Winter Semester 2015

Co-Supervisors : Dr. Scott Petrie and Dr. Hugh Henry
Degree Sought : MSc
An essential component of wildlife management and applied ecology is to understand how animals use habitat. Examining how an animal may select habitat can shed light on complex behavioural processes and their associated influence on fitness. Knowledge of how wood ducks and their broods move throughout their landscape, select habitats, and survive is valuable information for wildlife managers and ecologists. Duckling survival has a strong relationship with recruitment, therefore, population management can be improved through understanding the spatial and temporal dynamics of survival. I used radio-telemetry to monitor female wood ducks and broods to 30 days post-hatch. I determined what types of habitat wood ducks select for and modelled survival based on biotic and abiotic covariates. My research will improve our ecological understanding of wood ducks in Ontario and help refine management practices for nest box programs and brood rearing habitats.

Northern peatlands (a type of wetland) play an important role in accumulating atmospheric CO₂ and storing it as soil C in peat thereby contributing to ‘global cooling’ over the Holocene.  However, climate change is forecasted to be the most extreme in high latitudes where a significant amount of global C is stored in peat.  Enhanced decomposition through warming and possibly drying could result in northern peatlands becoming a net carbon source in the future, resulting in a positive feedback with the atmosphere. There is little experimental research on this question, particularly for fen peatland types even they account for about 50% of the total peatland area in Canada. My objective is to explore how strongly climate will alter peatlands carbon storage (i.e. direction, magnitude and drivers) with evidence from both mesocosm and field experiments in order to better model the fate of carbon in Canadian peatlands and their role in global carbon cycling.

Boreal forest ecosystems are nitrogen (N) limited, but sequester large amounts of carbon (C). Predicted elevated temperatures are expected to increase the demand for N. Moss-cyanobacteria associations (MAC) are a fundamental source for new N inputs through biological N₂ fixation. Although the effect of temperature on these systems and N₂ fixation and the fate of N are poorly understood I hope to  (1) understand the differences in N₂ fixation and growth of Nostoc punctiforme under elevated temperature in isolation and with mosses under controlled laboratory and field conditions and; (2) elucidate whether N₂ fixed by N. punctiforme is preferentially taken up by moss or ‘leaked’ in the ecosystem.

A heterogeneous landscape affects population structure, resulting in both neutral and adaptive genetic differences between populations. Understanding how populations are structured informs predictions about how they will respond to changes in their environment, which is especially important for species that may be vulnerable to climate change. I will examine population structure and adaptive variation in the alpine butterfly Parnassius smintheus in the context of the landscape, using single nucleotide polymorphisms (SNPs) as genetic markers. I will determine how landscape features such as forest cover affect P. smintheus population structure, and whether different landscapes result in adaptive variation. I will also investigate the effects of changing sampling size on calculating population statistics when using SNPs compared to microsatellites, to inform future sample collection.

MSc. Candidate
Supervisor: Dr. Irena Creed
Abstract: Models can be used to forecast large-scale ecological change, but physical processes are often complex and contain hidden frequencies at different times. My goal is to develop models that characterize water discharge across time and space, and relate observed changes to large-scale natural oscillations including the El Nino, North Atlantic, Pacific Decadal and Atlantic Multidecadal Oscillations, which may be affecting water discharge. I use wavelet analysis, which allows me to understand not only which oscillations are occurring but also when they are occurring. By decomposing water discharge time series into frequency and time sub-space, we can relate causes of seasonality to large-scale oscillations. 

Supervisor: Dr. Zoe Lindo
Degree: MSc

Climate change is expected to increase atmospheric carbon dioxide levels and global temperatures. In Boreal peatlands, these changes are expected to directly affect decomposition processes through enhanced microbial activity, and indirectly affect decomposition through changes in litter input and decomposability associated with changes in plant species composition. I will use Sphagnum spp., Carex magellanica and Chamaedaphne calyculata litter. First, I will quantify the decomposability and carbon release of the three species grown under ambient and elevated CO₂. Next, I will investigate how microbial communities use different carbon compounds under different temperature regimes. Finally, I will evaluate the interactive effects of temperature and elevated CO₂ on long-term decomposition. Northern peatlands are carbon sinks; understanding decomposition processes under future climate scenarios will help inform carbon budgets.

Genetic diversity is critical in shaping the adaptive capacity of populations and the fitness of individuals. In vertebrate animals, the Major Histocompatibility Complex (MHC) is the most polymorphic region in the genome and appears to be under strong balancing selection pressure. The adaptive importance of MHC genes makes these loci good candidates for comparing patterns of genetic diversity to those at neutral loci, and for examining the fitness consequences of MHC diversity. My research investigates the degree to which neutral and adaptive loci are correlated in terms of individual genetic diversity, and pairwise genetic similarity, in free-living song sparrows (Melospiza melodia). I will also examine patterns of selection at MHC class II b by examining how individual genetic diversity at this locus corresponds to annual survivorship.

Supervisor: Dr. Hugh Henry
Degree: M.Sc. (Entrance Seminar)
Climate change may expose plants to greater stress in many northern temperate regions. Specifically, increasing air temperatures may expose plants to greater frost and drought stress. Cross-adaptation occurs when exposure to one stress increases tolerance to a second, different stress. Interestingly, both frost and drought result in cellular dehydration, and can stimulate the production of similar protective compounds. What I will investigate is how frost stress influences drought tolerance, and in turn how drought stress influences frost tolerance in Kentucky bluegrass (Poa pratensis). I will take an ecological perspective and assess tolerance by examining the effects on plant growth. Understanding the interactions between stresses may help us better predict how plants will respond to climate change.

Supervisor: Dr. Greg Thorn
Degree: Masters
The Agaricomycetes are a class of fungi that include most typical mushrooms. Tall grass prairies are an endangered ecosystem and there is great interest in studying their biodiversity and endeavoring to restore them. Little is known about Agaricomycetes in the prairies – what is out there, why it is there, and how to best uncover this. I will use both traditional and molecular techniques to analyze mushroom and soil samples from a variety of tall grass prairies to address these questions. My three objectives are: to characterize the Agaricomycetes of Ontario’s tall grass prairies, examine factors that may influence their composition (geography, soil, plants, and tillage history), and compare results of two different survey methods (aboveground mushroom collecting and belowground soil molecular analysis).

Degree: PhD

Understanding how animals recognize their kin has been a major challenge for psychologists and behavioural ecologists for decades. Two common mechanisms of kin recognition are familiarity and phenotype matching. When familiarity is used, individuals remember kin whereas when phenotype matching is used, individuals instead compare putative kin to a template of what kin should look (or smell) like. The guppy (Poecilia reticulata) has become an important model species in evolutionary biology. It has been shown that some populations of guppies use familiarity whereas other populations use phenotype matching. Capitalizing on this dichotomy, I will use breeding crosses to establish the inheritance patterns as well as search for the gene or genes underlying the different kin recognition mechanisms.

Supervisor: Dr. Charles Trick
Degree: Masters
Prymnesium parvum is a widespread golden algae species that inhabits marine, estuarine and inland systems. It is known to form harmful algal blooms that can have devastating effects on ecosystems and fisheries. This is due to the toxins produced by Prymnesium parvum that target the gills in fish and molluscs. These toxins cause hemolysis and produce reactive oxygen species that lead to the asphyxiation of the affected organism. In other algal species, iron is known to influence toxin production. However, the effect of iron on Prymnesium parvum toxicity remains unknown. For my project, I will be investigating the effects of limited iron availability on toxin production in Prymnesium parvum by conducting hemolytic assays, hydrogen peroxide assays and assays using a model gill cell line.

Supervisors: Jeremy McNeil & Ian Scott
Degree Sought: MSc. Biology
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.

Common buckthorn (Rhamnus cathartica), a highly competitive Eurasian woody shrub, is currently invading North America.  Dense monoculture thickets of buckthorn reduce native plant species diversity and may also reduce diversity of soil organisms, including mycorrhizal fungi, negatively impacting surrounding symbiotic flora and facilitating invasional meltdowns. Manipulative garden experiments were done to assess the effects of root exudate, leaf litter and drupes, containing allelochemicals, on the diversity of naïve native arbuscular mycorrhizal fungi (AMF) associated with sugar maple (Acer saccharum) seedlings. Soil samples from sugar maple forests with and without buckthorn were surveyed for communities of soil fungi, including AMF.  Additionally, a comprehensive list of the local fungi occurring on buckthorn was generated in order to identify potential biocontrols.

Supervisor: Dr. Greg Thorn
Arbuscular mycorrhizal fungi (AMF) form symbiotic associations with the roots of many vascular plants. AMF exchange soil nutrients from nutrient pools that the plants cannot reach themselves in exchange for photosynthetically fixed carbon. Arbuscular mycorrhizal fungi are an essential component of tallgrass prairie ecosystems. My project is looking at the effects of agricultural tillage on species composition of arbuscular mycorrhizal fungi in Ontario tallgrass prairies. The objectives of my project are to use Next Generation Sequencing to compare species composition of arbuscular mycorrhizal fungi in sites with different disturbance histories and determine if there are potential indicator taxa for the ends of the disturbance spectrum. Understanding how disturbance affects AMF could reveal information on how AMF can be used for restoration of endangered ecosystems.

The coordinated movements of groups arise by collective decisions between group members.  Black-capped chickadees have a stable dominance hierarchy in which dominants obtain more long and short-term gains (good breeding territories and food resources), than subordinates.  There is still some uncertainty to why subordinates join flocks at all.  Chickadees will be radio-tagged and tracked throughout the winter and breeding seasons for several years in order to examine how social rank influences flock structure as well as the interaction of social rank and breeding area size, survivorship, and caching and roosting behaviours.  I predict that subordinates achieve more fitness than previously thought, and that radio-telemetry methods combined with observational methods will reveal more details regarding social structure than would be possible with observation methods alone. 

Predator effects on prey populations extend beyond direct killing through changes in prey physiology and behaviour that can affect survival and reproduction. Under high predation risk, prey should reduce conspicuous behaviours, such as courtship and mating, in order to reduce their risk of detection. Although limiting their reproductive behaviours may increase their chances of survival, it may also reduce their reproductive success. Therefore, individuals must balance the risk of predation and their investment into reproduction. To test these ideas, I experimentally manipulated the risk of predation during the breeding season and sampled courtship and mating behaviour in both male and female brown-headed cowbird (Molothrus ater). Any potential changes can be used to infer how predation risk alone can impact prey populations by affecting reproductive success.

Degree: PhD (exit)
Supervisor(s): Scott Petrie/Jack Millar
The Eastern Population Sandhill Crane (Grus canadensis) was extirpated from Ontario within the last 100 years.  The species is of conservation and management concern to the provincial and federal government of Ontario and Canada, respectively.  Thus, managers required basic population biology data along with targeted management information to make informed decisions relating to the species.  In consult with the governments, we selected the primary autumn staging site for the species to collect data to address this void.  We estimated multi-year minimum population estimates, fall recruitment, migratory chronology, roost site selection, and feeding ecology using direct observation, GPS tracking, and field experimentation to address our management and research objectives.  Our results will inform wildlife managers as well as provide novel behavioural ecology data to the scientific community and beyond.

Supervisor: Graham Thompson
Degree: Masters
As social insects, termites typically live in kin-based colonies that are replete with sterile workers and soldiers. Despite their sterility, workers and soldiers can potentially gain indirect fitness by directing help towards reproducing relatives and defending against unrelated intruders. For invasive populations, however, these kin-mediated behaviors break down, leading to the formation of mixed-kin supercolonies that occupy vast areas. One potential explanation stems from the genetic consequence of the invasion itself; invasive populations go through a genetic bottleneck that strips them of alleles essential for recognition. If so, then invasive should have lower genetic diversity than non-invasive populations. In this study, I will use next-generation sequencing analysis to test this prediction on a genome-wide scale.

MSc Exit Seminar
The perceived risk of predation (i.e. the ‘fear’ of predators) can impact prey populations through behavioural and physiological changes that significantly affect survival.  Increased predation risk has been shown to induce body mass change in several bird species. Consequently, it is assumed these predator-induced changes in mass may affect an individual’s ability to evade predatory attack by altering flight performance (i.e. takeoff speed, ascent angle). By manipulating the level of predation risk in the environment, my research is specifically focused on how brown-headed cowbirds (Molothrus ater) respond physiologically to the increased risk of predation and aims to test the assumption that predator-induced mass change will affect various measures of flight performance.

Endurance flight during migration and immune system functioning are two very energetically costly activities for birds. Since nutritional resources are limited, there may be a trade off between migration and immune investment. Avian blood parasites consume host resources, which may further decrease a bird’s resource pool to the point where endurance flight and immune defense may not be possible simultaneously. I examine and compare naturally occurring levels of blood parasite infection in a migrating songbird population by microscopy and molecular methods. The prevalence and intensity of infection is compared to measures of immune defense, and the impact of infection intensity on endurance flight performance is assessed. Studying host-parasite interactions within the context of migration will help to improve knowledge of the ability of birds’ to migrate and spread disease over large geographic distances.

Supervisor: Dr. Greg Thorn
Arbuscular mycorrhizal fungi (AMF) form symbiotic associations with the roots of many vascular plants. AMF exchange soil nutrients from nutrient pools that the plants cannot reach themselves in exchange for photosynthetically fixed carbon. Arbuscular mycorrhizal fungi are an essential component of tallgrass prairie ecosystems. My project is looking at the effects of agricultural tillage on species composition of arbuscular mycorrhizal fungi in Ontario tallgrass prairies. The objectives of my project are to use Next Generation Sequencing to compare species composition of arbuscular mycorrhizal fungi in sites with different disturbance histories and determine if there are potential indicator taxa for the ends of the disturbance spectrum. Understanding how disturbance affects AMF could reveal information on how AMF can be used for restoration of endangered ecosystems.

Supervisor: Brock Fenton
The echolocation calls that bats use to navigate their environment and find food can also play a social role. When nectar-feeding bats converge on a food source, they may rely on different calls to minimize the chances of mid-air collisions and interference by others. To explore this possibility, I conducted playback experiments with two species: Glossophaga soricina and Leptonycteris yerbabuenae. I predicted that these bats use echolocation calls and/or social calls to change flight behaviour and feeding approaches, or to effect ‘air traffic control’ while feeding. I investigated this by presenting a variety of playbacks to captive and wild bats and analysing behavioural responses and flight patterns. My research will improve our understanding of the role that these calls play during social interactions at feeding sites.

The production of androgens is hypothesized to have immunosuppressive effects in vertebrates. Here, I test this idea in bluegill sunfish, Lepomis macrochirus, by comparing the immune responses mounted by distinct male morphs in response to a vaccination. Sneaker males produce low levels of androgens and are thus expected to mount stronger immune responses than parental males, who produce relatively high levels of androgens during spawning.  Fish that were held in captivity following vaccination appear to have been highly stressed, so I have excluded their data from most of my analyses. Freshly caught fish of both male morphs demonstrate a positive relationship between their androgen production and white blood cell concentrations. I discuss these findings and their implications for the immunocompetence handicap hypothesis.    

Recent research has have begun to provide important insights into the origins and destinations of migratory bats, but fewer studies have examined how bats budget their time and energy en-route. Previous work in our lab found that during fall migration silver-haired bats (Lasionycteris noctivagans) use a torpor assisted migration strategy, which dramatically reduces daytime thermoregulatory costs, increases net refueling rate, and facilitates very brief stopovers. However, spring and fall migration pose different challenges. The concurrence of migration and pregnancy in the spring creates a conflict for female bats. Daily torpor use will spare energy stores for migratory flight, but may delay fetal development. Thus, sex may substantially affect the energy and time management of spring migrants in ways that wouldn’t occur during the fall. My research investigates sex differences in several aspects of spring migration ecology: arrival date phenology, body composition, stopover duration, torpor expression and migratory routes.  

Parasites are taxonomically and geographically widespread, and place important selective pressures on their hosts. Most studies exploring host-parasite coevolution have done so in the context of host species with predictable geographic ranges. Virtually nothing is known about host-parasite coevolution in hosts with nomadic distributions, such as red crossbills (Loxia curvirostra). Compared to most songbirds, marked vocal variation exists amoung red crossbill populations. Individuals with different vocal types also differ in feeding capabilities. In this study, I used genetic techniques to determine how haematozoan parasite communities differ among 4 ecologically and behaviourally isolated populations of nomadic songbirds. I screened 640 free-living red crossbills; 76 birds were found to be infected and sequences obtained were used to construct phylogenies of parasite lineages