April 6, 2018
Temperature is an important factor that affects all organisms due to its effect on rates of biochemical reactions; however, it is most important in ectotherms because their internal temperature is closely linked with the environment. Global climate change models predict that water temperatures worldwide will continue to rise, and this increase in temperature may challenge the capacity of aquatic organisms to persist in their current habitats. Our project aims to further understand how plasticity and genetic adaptation shape thermal performance in Atlantic salmon (Salmo salar). We examined phenotypic plasticity by rearing our salmon at two different temperatures, and examined genetic variation by looking at three different populations. We measured critical swim speed (aerobic) and burst swim speed (anaerobic) across 8 temperatures. These thermal performance measures are complemented by assessments of temperature preference. We will discuss how these data can help to understand how fish will respond to changing thermal environments.
Northern peatlands are long-term carbon (C) sinks, and changes in C storage under climate change is of considerable interest due to the high sensitivity of peatlands to environmental changes. Moss- and vascular plants-dominated peatlands have different C storage and are two prevailing but understudied peatland types in Canada. Climate change could shift peatlands from moss-dominated towards vascular plants-dominated, making future peatland C storage highly uncertain. Using greenhouse experiment, my research firstly investigated how increased temperature (T) and carbon dioxide (CO2) affected C cycling via altered plant biomass allocation in vascular plants-dominated peatlands. Additionally, a field experiment was set up to experimentally examine effects of increased ground T and atmospheric CO2 on greenhouse gas fluxes and dissolved organic carbon chemistry in two peatlands types. C balance data prior to the initiation of warming were used to preliminarily evaluate changes in peatland C storage if a vegetation shift occurs under climate change.
March 23, 2018
Methylmercury (MeHg), the organic, neurotoxic form of mercury, is produced in anoxic wetland sediments and biomagnifies in aquatic food webs. The first step of bioaccumulation in some systems, uptake of MeHg from the water column by phytoplankton, will be affected by increased primary productivity and dissolved organic matter (DOM) as a result of climate changes. MeHg binds strongly with organic matter, and DOM concentrations increase in water bodies as permafrost-dominated catchments thaw. Conversely, MeHg also partitions from water to algal cells. Under climate change, primary productivity is expected to increase; so, algae and DOM may “compete” for MeHg binding, resulting in unknown consequences for mercury bioavailability in climate change-impacted regions. My proposed experiments will quantify partitioning of MeHg to algal cells in the presence of different types of DOM, in order to better understand the effects of catchment-derived DOM on mercury bioavailability in northern lakes affected by climate change.
With climate change and associated climatic instability, populations are expected to experience more frequent and severe fluctuations in size, resulting in demographic bottlenecks. These population size fluctuations have strong effects on genetic variation, which is a central concern for conservation. Using long-term demographic data and samples collected over several years, I studied the population genetic consequences of demographic bottlenecks, within a network of interconnected populations of the alpine butterfly, Parnassius smintheus, taking into account the effects of landscape structure. Severe reductions in population size are becoming more frequent in this population network with unfavorable over-wintering conditions resulting from climate change. I also investigate how adaptive genetic variation in a population network is affected by recurrent population collapses. This study provides insights into how natural selection, drift, and gene flow shape genetic diversity and differentiation in dynamic populations occupying heterogeneous landscapes.
March 9, 2018
Social insects are characterized by sub-fertile castes that evolve via indirect selection, yet little is known about how this type of selection affects rates of molecular evolution. On the one hand, genes indirectly selected for subfertility may experience relaxed adaptive molecular evolution, relative to genes directly selected for reproduction. On the other hand, genes associated with sub-fertile castes may be less constrained and thus, free to evolve rapidly. These potential yet contrasting 'signatures of kin selection' remain unresolved. In this study, I propose to test for differences in the rate of adaptive molecular evolution across caste-biased and un-biased genes from a subterranean termite. Specifically, I will exploit allelic diversity captured in a newly available RNA sequence data set to reveal differences in patterns of nucleotide substitution that are associated with the sub-fertile castes.
Peatlands are wetlands typically dominated by sphagnum mosses, have >40 cm of organic soil, and are ubiquitous across the boreal forest ecozone. The nutrient-poor soils are dominated by anaerobic microbes, including methanogenic archaea and sulphate-reducing bacteria (SRB). The SRB are principal methylators of inorganic mercury (Hg) in the environment, and are the primary reason why peatlands are ‘hotspots’ for methylmercury (MeHg) production. As MeHg is the toxic, bioaccumulating form of Hg, factors that control the activity and composition of SRB communities in peatlands are important for understanding MeHg in the environment. Recent research suggests that historically elevated sulphate inputs result in enhanced MeHg production, even if sulphate inputs are now much lower. My MSc research will focus on understanding this sulphate ‘priming’ effect on SRB and methylation through a series of laboratory experiments on pristine and sulphate-impacted peat soils, as well as an investigation of mine-impacted peatlands in northern Ontario.
March 2, 2018
Population control of an invasive species, such as the Asian pentatomid Halymorpha halys Stål (Pentatomidae), is possible using parasitoids originating from the invasive insect’s native range. Before a biocontrol agent can be released into a new region, the control agent efficacy and non-target effects should be investigated. The project under development will explore the biology and physiological host range of the hymenopteran Asian parasitoid Trissolcus japonicus (Ashmead) for determining control potential, as well as non-target effects this parasitoid may pose to native pentatomids, if released in Southern Ontario to reduce invasive H. halys populations. A second component to the study will compare belowground community bottom-up effects on parasitoid species diversity in different Pentatomid-based host-parasitoid species interaction networks. Greater knowledge about how host-parasitoid networks vary by agroecosystem – in this case by soil treatment - could lead to more accurate assessments of the need/benefit of biocontrol agent release programs.
Predators affect prey populations not only through direct killing, but also through perceived predation risk – the ‘fear’ of predators. Responding to predation risk is critical for prey survival, however perceived predation risk can have lasting effects ranging from individual changes in neurobiology up to population level effects. During my Masters, I found lasting changes in the brain one week after exposure to perceived predation risk in semi-natural conditions. For my PhD, I will be looking at the effects of perceived predation risk on the brain and behaviour of free living birds. To experimentally test the lasting effects of predator ‘fear’, I will be manipulating perceived predation risk using auditory playbacks to assess the long lasting effects on the brain and behaviour. My research aims to integrate results from biomedical research showing long-lasting fear effects on the brain in lab animals with fear-induced behavioural changes documented by ecologists in the field.
February 16, 2018
Bank Swallows (Riparia riparia), a threatened species in Ontario, breed primarily in either banks at lakeshores or at exposed surfaces in man-made pits. Though, pits containing a waterbody may act as intermediate habitat type. Pits are suspected to be ecological traps for this species but the relative trade-offs between using these nesting sites are poorly known. Availability of aquatic emergent insects is expected to be highest at lakeshore colonies with associated nutritional benefits including omega-3 fatty acids. However, Bank Swallows may experience differential mercury exposure among sites and so, diet quality and location are expected to influence juvenile body condition. This study seeks to compare these breeding habitats to evaluate mercury exposure, dietary differences, and body condition. This information will be important for management decisions related to the use of pits by this species and conservation of suitable nesting habitats.
In their natural habitats, wildlife faces multiple stressors (i.e. predation, food unpredictability, climate change) in addition to pollutants burden. While evidences suggest that stress worsen the impact of contamination, toxicant exposure also alter the ability to cope with stressful situations, but studies on the topic are rare. Such impairment brings high risks for animals, especially during energetic life stages such as migration. This PhD project aims to determine the relationship between stress and mercury exposure and consequences on birds’ health. Therefore Song Sparrow (Melospiza melodia) adults and juveniles will be captured and dispatched in four environmentally relevant treatment: control, stressed, mercury exposed, and both stress with mercury exposition. An immune, hormonal, neurologic, behavioural and metabolic approach will be applied to monitor their health. This study will inform on mercury toxicological pathway and help to evaluate if the tolerated contaminant levels in the wild are relevant or more harmful than initially thought.
February 9, 2018
It is estimated that billions of birds worldwide die each year from window collisions. Birds appear to behave as if windows are invisible, suggesting they cannot distinguish between glass and open space. The objective of my MSc research is to determine if some bird species are more vulnerable to dying from window collisions than others. Using a combination of citizen science and bird monitoring data from the Fatal Light Awareness Program (FLAP) and regional bird banding stations, I will determine if the mortality seen in downtown Toronto is simply a function of species abundance or if it is unequal among species. In addition to among species differences in mortality, I will compare individuals within species to address if age is a factor in collision mortality vulnerability. To determine this, I will use the FLAP 2017 and 2018 bird collections to identify individuals by species, sex and age. This information will be used to estimate the age and sex ratios to test if there are unequal occurrences.
The true armyworm moth, Pseudaletia unipuncta (Noctuidae: Lepidoptera), is a seasonal migrant. In order to avoid deleterious summer conditions, true armyworm moths undergo a northward spring migration to southern Canada. To avoid winter conditions, their progeny will then take on a southward fall emigration to southern United States. The pattern of their migration has been documented by correlating deuterium found in mean annual precipitation and wing chitin of true armyworm wings. However, it is unclear as to what happens during their migration. It has been established that majority of female spring immigrants have mated at least once, due to the presence of spermatophore(s). By analyzing the isotopic composition of spermatophores we may be able to determine where the males are potentially coming from. Correspondingly, we would be able to further enhance pest management strategies to target the specific areas, where majority of males and correspondingly females are feeding.
February 2, 2018
The last few decades have seen radical shifts in our thinking about the phenomenon of bird migration. These shifts have largely been driven by novel uses of chemical analysis tools, and the miniaturization of tracking technologies. New methods have in turn has led to a new understanding of the ecological complexities of the life cycles of migratory birds. I will discuss findings from my Master’s research, where I used both geolocators and stable isotope analysis to study the migratory connectivity of the Wood Thrush. I will conclude with the principlal research questions for my doctorate, in which I aim to investigate the role of hormones in regulating migratory behaviour.
Both resident and migrant birds attempt to synchronize breeding with the spring green-up, when high protein food sources ideal for provisioning offspring are at their greatest abundance. Some bird species, however, do not follow this typical timing. Grey Jays (Perisoreus canadensis), for example, nest during the cold winter months, well prior to Spring green-up. This early breeding timing presumably presents unique challenges and suggests that Grey Jays must use an alternative method of provisioning their offspring. In my work, I examine the relationship between this early breeding cycle and food caching, a food storage strategy exhibited by Grey Jays. Grey Jays store food in the Fall, and it is possible that these food stores are retrieved in the Spring and used to provision young. If so, this would be a novel provisioning strategy, and could elucidate the means by which Grey Jays are able to breed when most birds cannot.
January 26, 2018
Demographic responses to recent climatic events may offer insight into how climate change will affect future populations, many of which are likely to exist in fragmented landscapes. Fragmented landscapes influence the amount and distribution of genetic diversity within populations, which in turn are important for population persistence. Using landscape genetic techniques, I will examine the effects of landscape composition, configuration, and climate-related demographic bottleneck events on inbreeding within a metapopulation of the alpine butterfly Parnassius smintheus Doubleday. Additionally, I will explore the role habitat patch connectivity may play in alleviating inbreeding following each bottleneck event. I expect that 1) an increase in observed homozygosity resulting from bottleneck events will lead to a reduction in fitness in contemporary individuals; and 2) patch connectivity will be positively associated with the rate at which genetic diversity is recovered, and inbreeding reduced, within habitat patches.
Schools of fish, herds of elk, plagues of locusts - sometimes, animals form conspicuous groups in which individuality appears to be subsumed within a larger social network. Even our own species is characterized by vast networks of family and friends that change over an individual’s lifetime. Presumably, the emerging social networks are not random, but reflect attractive or repulsive tendencies that are relevant to each species. In this study, I am using social network analysis to test how living populations of fruit flies interact as a function of genetic and environmental circumstance. Specifically, I am testing how the number and nature of inter-individual encounters vary with i- population density, ii-genotype, and iii- sex ratio, among other predictors of social space. So far, I have developed an assay to video-capture interactions, re-draw this information as a graphical network, and extract from the graphs social information that I use to test hypotheses.
January 19, 2018
Climate warming is expected to shift aboveground plant community and this has consequences for belowground microbial community in terms of litter inputs. I will examine the passive warming effects on plant communities in Boreal peatlands, and how potential associated shifts in litter quality will affect microbial carbon use (i.e. whether microbes sequester this carbon as biomass or respire this carbon as CO2). I expect a shift from Sphagnum (moss) dominated communities to Carex (graminoid) dominated communities under warming, and corresponding increases in litter quantity with more easily accessible carbon for microbial communities. Boreal peatlands are an important system to study aboveground and belowground carbon linkages as they have large carbon sequestration abilities associated with low decomposition rates, making them significant global carbon sinks. My research aims to evaluate shifts in Boreal peatland plant communities under passive warming and to determine how changes in litter carbon quality influences microbial carbon use.
Aerial insectivores are a guild of birds who are facing extensive population declines. However, the rates of these declines vary across species. This is the case for Barn Swallows (Hirundo rustica), Cliff Swallows (Petrochelidon pyrrhonota) and Tree Swallows (Tachycineta bicolor), three aerial insectivore species that breed in Southern Ontario. Although these species share many similarities, Barn Swallows have declined at a much faster rate. One explanation for this is niche partitioning wherein the three species are using the environment differently to limit competition. If the three species exhibit distinct niches, they may be experiencing differential pressures. For my thesis, I will be focusing in on differences in nestling diet and post-fledging movements of these swallow species. Using DNA barcoding and feather stable isotope analysis to examine diet as well as the Motus Wildlife Tracking System to examine post-fledging movements, I hope to find a possible explanation for the differential declines.
January 12, 2018
Seasonality of social behavior is widespread in birds which makes this group an excellent model to study social dynamics like: group fusion-fission, and activity synchronization. Since our understanding of these processes is mostly theoretical, studies that examine social dynamics in an ecological context are needed. I constructed a network of automated radio-towers in a 60 hectare forest to track multiple flocks of radio-tagged Black-capped chickadees through the winters of 2016-2018. Seasonal “radioprofiles” indicate that: flocks can be identified from telemetry data alone, flocks of birds have differing activity schedules, and individual movement between flocks (fission) can be studied. This research shows that automated telemetry can effectively study social behavior on the level of the individual and flock directly in the field. This method provides for a deeper understanding of social evolution by examining real-time social dynamics simultaneously across multiple groups in a natural setting.
Seasonal migration exposes animals to a variety of habitats and parasites, thus energetic constraints may prevent investing in immunity and migration. If infected birds migrate successfully then there is potential for them to transport infectious disease long distances. To determine whether parasitic infection alters or interferes with songbird migration, I inoculated songbirds with malaria parasites ( Plasmodium spp.) in two experiments. First, captive white-throated sparrows ( Zonotrichia albicollis) were inoculated in late winter (spring migration), whereby I assessed nocturnal migratory restlessness and body composition (fat mass, lean mass, and hematocrit). Second, I inoculated song sparrows ( Melospiza melodia) in captivity and released them prior to fall migration to determine the effect of malaria infection on migratory departure timing. Results indicate that mere exposure to malaria can impact host migratory behaviour and the degree of impact is specific to the stage of infection.
|DATE||FIRST SPEAKER||SECOND SPEAKER|
|Mar. 2||William Laur (I)||Lauren Witterick (I)|
|Mar. 9||Anna Chernyshova (I)||Jennifer Blythe (I)|
|Mar. 16||No seminars|
|Mar. 23||Kyra Simone (I)||Maryam Jangjoo (E)|
|Mar. 30||Good Friday|
|Apr. 6||Nicole Zathey (E)||Jing Tian (E)|