Bill Nelson - Associate Professor
I am interested in the interaction between ecological and short-term evolutionary dynamics, and how this influences patterns of diversity we see in nature. We use life-histories as a focal point to connect these processes, and are broadly interested in understanding how life-histories scale up to the biological dynamics of populations and communities. Our lab uses four study systems with pronounced stage-structure (freshwater zooplankton, bacterial parasites, cowpea weevils, and tortrix moths), and our research combines mathematical modeling, laboratory experiments, and field-based mesocosm experiments. We also collaborate with a number of other researchers tackling questions such as the influence of environmental gradients on zooplankton community productivity and the role of resource consumption on malaria parasite evolution. Have a look around the website to see more about our research and to meet our lab group.
Current projects: Population dynamics, disease ecology, life-history (co)variation, evolution in simple food webs, coexistence of multiple behavioural traits.
Clay Cressler – Postdoctoral Researcher
At the broadest level, I study how an organism’s life history is shaped by ecological and evolutionary processes. Currently, my research is focused on understanding how the within- and between-host dynamics of infectious disease are shaped by the processes of host energy acquisition and allocation. A lot of my work involves the development of mechanistic mathematical theory, but I use ecological experiments with the Daphnia magna–Pasteuria ramosa host-parasite system to help ground and test that theory. I am currently developing molecular tools to help better understand what the parasite is doing inside the host. I also have an active research program developing, testing, and applying methods for phylogenetic comparative analysis.
Current Projects: Daphnia–Pasteuria disease dynamics
Leslie Holmes – PhD Student
My research interests are focused on the evolutionary consequences of community interactions. Communities are comprised of a network of inter-connected food chains, where species interact both directly, (e.g. predator-prey interactions), and indirectly, (e.g. apparent competition). These ecological interactions play an important role in community dynamics. As communities grow in structure and complexity, more and more interactions are present concomitantly and when it comes to the evolutionary consequences of these direct and indirect interactions, the role of each is not clear. Using experimental biology on a host-parasitoid community, I aim to disentangle the roles direct versus indirect ecological interactions play on the evolutionary dynamics of simple food webs.
Current Projects: Direct versus indirect ecological interactions in a host-parasitoid food web
A central question in evolutionary ecology is: “Why is there such incredible diversity and how is it maintained?” How are distinct genotypes/phenotypes maintained over spatial scales where substantial gene flow is expected and population distributions overlap? To address this question, I am interested in exploring how life history evolution in natural populations of zooplankton may scale up to affect population dynamics. Through an emphasis on the relative importance of selective forces in nature (such as environmental gradients), I am currently investigating the possible mechanisms responsible for zooplankton adaptation and co-existence at fine spatial scales. My approach to testing these ideas is with experimentation in the field.
I am broadly interested in the implications of food variation on ecological and evolutionary processes, because as one saying goes ‘everybody’s gotta have lunch’. The overarching theme of my master’s research was the influence of a food quality gradient on life history variation among and within Daphnia genotypes, as a way of providing a candidate explanation for the second paradox of the plankton. I used a tightly controlled environment and Daphnia‘s clonal reproduction to tease apart the relative influences of genetics and environment on their life history. My work is applicable in an energetics framework examining resource allocation differences when resource acquisition is controlled.
Our field site is an oligotrophic lake at the Queen’s University Biological Station. I propose that food availability in Round lake has a strong influence on the structure of the daphnia population. Daphnia are herbivorous creatures that feed primarily on phytoplankton but can also feed on bacteria. Observations and lab tests have shown that hemoglobin can be an indicator of habitat choice. The red phenotypes frequent low oxygen depths in increasing numbers as fall approaches. Life history traits of D. pulicaria in this meromictic lake should provide some insight into the trajectory of this species based on a time series for 2014 and 2015.
Current Projects: The Daphnia pulicaria population in Round Lake and the less frequent D. schodlerii.
I graduated from St. Lawrence College with a 3 yr advanced diploma as a Biotechnology Technologist. I completed a 4 month placement in the Nelson lab under Markus Dyck, examining if life history can be used to predict population abundance and extinction risk, in the southern cowpea weevil. After spending a month in South Africa, at a vet camp, assisting with the extraction of tissue DNA, I am currently working as a lab technician in the Nelson Lab with the moth species Adoxophyes honmai, Tea tortrix moth. I research how seasonal temperature changes influence the stability of population dynamics.
Current Projects: Tortrix Tea Pest
Roisin Donohoe – Undergraduate student
Currently in the final year of my undergraduate degree, I am investigating the Daphnia magna-Pasteuria ramosa host-parasite system with an emphasis on trying to understand the influence of other biotic factors such as predation.
Current projects: Daphnia-pasteuria interactions
I am currently completing my BscH in biology. I am researching bacteria life cycle stages and infection energetics using the Daphnia magna-Pasteuria ramosa model system. My research focusses on timing of the bacterial life cycle, and staging the energetic effect of the bacteria on its host.
Current projects: Daphnia-pasteuria interactions
Past Graduate Students
Andrew Lowles (M.Sc., 2013) Thesis: “Effects of environmental factors, physical barriers and season on the fish community composition of the lower Ottawa and Mississippi river systems as determined from quantitative electrofishing”. Co-supervised with John Casselman.
Where am I now?: 2014 Sport fish development officer at the Nova Scotia Department of Fisheries and Aquaculture.
Where am I now?: 2012 Veterinary School, London England.
Past Honours Thesis Students
Catherine Byrne Thesis: “What is the optimal immune efficiency for host-pathogen interactions?”
Adam Zunder Thesis: “What does exogenous juvenile hormone exposure tell us about the life history of the smaller tea tortrix moth (Adoxophyes honmai)?”.
Where am I now?: 2014 MSc in Biomedical Communications, University of Toronto.
Michael Evans Thesis: “How do different seasonal temperatures affect the development of the smaller tea tortrix moth (Adoxophyes honmai)?”
Joanne Pham Thesis: “Population dynamics of different genotypes of Daphnia pulicaria under varying food qualities.”
Japteg Singh Thesis: “The influence of food quality & larval density on the life history of Callosobruchus maculates.” Co-supervised with Steve Lougheed
Jillian Gauld Thesis: “Phenotypic plasticity and life history trade-offs in zooplankton hemoglobin production.”
Tori Donovan Thesis: “Effects of lake water vertical variation in dissolved oxygen on selection among Daphnia pulicaria genotypes.”
Amy MacMullin Thesis: “The influence of in situ temperature and oxygen on individual Daphnia pulicaria growth and survivorship in a thermally stratified lake”
Louise Lam Thesis: “The effects of food availability during development on dispersal of cowpea weevils Callosobruchus maculatus (Coleoptera : Chrysomelidae).” Co-supervised with Steve Lougheed
Ashley McGirr Thesis: “Experimental determination of system dynamics in zooplankton.”
Jon Jeffery Thesis: “Respiration rate of zooplankton across oxygen and temperature gradients at high and low quality food.”
Alison Wardlaw Thesis: “Human behaviour in infectious disease outbreaks.” Co-supervised with Troy Day
Sita Ollek Thesis: “Consequences of multiple resource limitation on energy budgets: experiments and theory.”
Judy Oh Thesis: “The influence of nutrient limitation on zooplankton growth and mortality.”