The Role of Habitat in Ecology & Evolution
In a broad sense, I am interested in how habitat shapes and constrains the ecology and behaviour we observe in living organisms. After seven years of field experience in the working world, preceded by several undergraduate research assistantships, I’ve come to the conclusion that knowledge of an animal’s physiology and the underlying genetic makeup are critical for a thorough understanding of their natural history. Studying physiology allows us insight into the evolution of their ecological and behavioural traits, and thus, into how habitat provides a template for adaptation through natural selection.
The Role of Stress Physiology in Ecology & Evolution
The stress axis is a key neuroendocrine control mechanism mediating the relationship of vertebrate organisms to their environment. It allows them to react to psychological, social and environmental stressors, and thus permits survival in the face of short-term adverse conditions.
The stress axis is also involved in transitioning organisms from one biological phase to the next, such as changes between reproductive and non-reproductive states, and is therefore critical in an organism's attempt to maximize fitness, and in permitting long-term evolutionary responses to ecological pressures. I am interested in how stress-related physiological traits differ between species, and in what these differences might tell us about the evolutionary history of the stress axis and its role in adapting organisms to their surroundings.
The stress axis is also involved in transitioning organisms from one biological phase to the next, such as changes between reproductive and non-reproductive states, and is therefore critical in an organism's attempt to maximize fitness, and in permitting long-term evolutionary responses to ecological pressures. I am interested in how stress-related physiological traits differ between species, and in what these differences might tell us about the evolutionary history of the stress axis and its role in adapting organisms to their surroundings.
My Role in the Study of Physiological Ecology & Evolution
To get at these matters of interest, I use the concept of comparative physiology, with a particular focus on stress axis traits in species of the squirrel family, Sciuridae. Sciurids are a large family within one of the most successful mammalian orders, Rodentia, and occur on all continents except Australia and Antarctica. Their ecology and phylogeny are well studied and all of these aspects make squirrels a useful group for comparative investigation.
My M.Sc. research involved the comparison of species-specific stress physiology among five North American sciurids that are closely related and share the same forests. By measuring seasonal fluctuations in numerous stress axis properties in American red (Tamiasciurus hudsonicus) and Eastern grey (Sciurus carolinensis) tree squirrels, northern (Glaucomys sabrinus) and southern (Glaucomys volans) flying squirrels, and a ground squirrel, the eastern chipmunk (Tamias striatus), I was able to look at how the differences in their stress physiology helps to explain their natural and life history traits, and thus shed light on how they’ve evolved to fill their respective niches within a forested habitat (manuscripts in preparation).
An intriguing finding in the stress physiology of northern and southern flying squirrels has formed the basis of my Ph.D. research. My masters work revealed that these two species have high cortisol levels, but very low corticosteroid-binding globulin (CBG; an important regulatory protein) levels and that this character state is unique among the vertebrates. As part of the Kawartha Flying Squirrel Project, I am therefore using the flying squirrels as a comparative model to look into the evolutionary history of the stress axis among sciurids and among mammals in general. By determining the genetic and protein sequences of CBG and of tissue receptors for cortisol, and other related properties such as binding affinities and tertiary protein structure in as many squirrel species as possible (including Old World flying squirrels), I can construct a phylogeny based on these characters. Mapping this information onto the ecology and natural history of these species will give us insight into how the stress axis may have assisted organisms in adapting to a variety of habitat types throughout evolutionary time, and conversely, how habitat influences variation in stress axis function.
My M.Sc. research involved the comparison of species-specific stress physiology among five North American sciurids that are closely related and share the same forests. By measuring seasonal fluctuations in numerous stress axis properties in American red (Tamiasciurus hudsonicus) and Eastern grey (Sciurus carolinensis) tree squirrels, northern (Glaucomys sabrinus) and southern (Glaucomys volans) flying squirrels, and a ground squirrel, the eastern chipmunk (Tamias striatus), I was able to look at how the differences in their stress physiology helps to explain their natural and life history traits, and thus shed light on how they’ve evolved to fill their respective niches within a forested habitat (manuscripts in preparation).
An intriguing finding in the stress physiology of northern and southern flying squirrels has formed the basis of my Ph.D. research. My masters work revealed that these two species have high cortisol levels, but very low corticosteroid-binding globulin (CBG; an important regulatory protein) levels and that this character state is unique among the vertebrates. As part of the Kawartha Flying Squirrel Project, I am therefore using the flying squirrels as a comparative model to look into the evolutionary history of the stress axis among sciurids and among mammals in general. By determining the genetic and protein sequences of CBG and of tissue receptors for cortisol, and other related properties such as binding affinities and tertiary protein structure in as many squirrel species as possible (including Old World flying squirrels), I can construct a phylogeny based on these characters. Mapping this information onto the ecology and natural history of these species will give us insight into how the stress axis may have assisted organisms in adapting to a variety of habitat types throughout evolutionary time, and conversely, how habitat influences variation in stress axis function.