I hail from Toronto, ON but spent most of my childhood in Winnipeg, MB. I was fond of biology at a young age felt compelled to explore and understand species diversity and adaptation. In 2004 I moved back to Ontario to attend the University of Guelph, where I developed a passion for insects and other invertebrates during my B.Sc. in Zoology and M.Sc. in Environmental Biology. In my undergraduate honours thesis I investigated the influence of terrestrial isopods on leaf litter microbial communities and litter decomposition (supervised by Dr. Jonathan Schmidt, Dr. Marc Habash, & Dr. Sigrun Kullik). My M.Sc. under Dr. Hallett was a study of the patterns of diapause entry and emergence in the swede midge, Contarinia nasturtii (Diptera: Cecidomyiidae), an invasive agricultural pest of crucifers in Ontario.
In temperate regions, insect performance is bounded at low temperatures by the critical thermal minimum (CTmin). Below the CTmin, insects enter chill coma: a reversible state of paralysis resulting from a decline in muscle equilibrium potential. Improved low-temperature performance and survival may be achieved through plastic and adaptive mechanisms that lower the CTmin. Chill coma is accompanied by a disturbance in ionic concentrations across the gut and Malpighian tubules (the sites of insect ion homeostasis), changing haemolymph composition and leading to depolarization at the muscle. Temperature-dependent failure of gut epithelial ion regulation is therefore likely to explain the onset of chill coma, with variation in CTmin driven by epithelial pump and channel modification, but this model has yet to be tested.
As a recent addition to the Sinclair Lab I will be exploring the mechanisms underlying the CTmin. My models for this work, which encompass evolved differences and phenotypic plasticity in the CTmin, are the crickets Gryllus pennsylvanicus and G. veletis. G. pennsylvanicus overwinter as eggs and adults are cold-susceptible but exhibit some cold tolerance plasticity. G. veletis overwinter as nymphs and are relatively more cold tolerant.
My main goals are to:
1) Verify that low-temperature failure of gut and Malpighian tubule epithelial transport corresponds with the CTmin.
2) Identify candidate molecules associated with within- and among-species variation in CTmin.
Atomic Absorption Spectrophotometry (to measure ions in fluids or tissues)
RNA work / differential gene expression
Denaturing Gradient Gel Electrophoresis (DGGE)
Chloride ion measurement via ion-selective microelectrode
CTmin & supercooling point measurements for small ectotherms