Grant: Discovery Grants Program - Individual

Understanding how different populations respond to changing environmental conditions throughout their species' distributions is fundamental to the conservation of fishes. Temperature is one of the major environmental factors that determines the distributions of fishes. Phenotypic plasticity along with genomic divergence leads to differences in thermal tolerance phenotypes expressed among populations along environmental gradients. The mechanisms that lead to population-specific responses to high water temperatures in fishes are poorly understood. The long-term goal of my research program is to identify the physiological mechanisms involved in population-specific differences in thermal tolerance and to characterize the physiological signatures of local adaptation in fishes across large environmental gradients. I will use gene expression profiling and physiological assessments to identify responses to high water temperatures among fish populations throughout their natural and introduced ranges. In addition to their significant cultural, economic and ecological importance, Chinook salmon (Oncorhynchus tshawytscha) are ideal for studying the physiological mechanisms associated with thermal tolerance due to their large native range and disparate thermal distributions. Additionally, Chinook salmon have been stocked in systems outside of their natural distribution (e.g., Great Lakes of North America), providing an excellent opportunity to investigate how rapidly species can adapt to new environments. The short-term objectives of this research are: 1) to examine the effect of exposure to high water temperature on fishes during early developmental stages with the phenotype expressed later as juveniles; 2) to compare the physiological and transcriptome-wide responses to high water temperatures of different populations throughout their natural and introduced ranges; 3) to identify the variation associated with temperature acclimation among populations - a hallmark of genomic divergence. Differences in thermal stress responses observed in nature are generally influenced by environmental factors and genomic variation. Therefore, using experimental approaches to control environmental influences, thermal tolerance associated with genomic variation among populations will be assessed. The significance and impact of this innovative work are its synthesis of how environmental conditions, plasticity and adaptive divergence contribute to phenotypic differences among fish populations. This work will advance our understanding of population-specific thresholds for thermal stress responses in ectotherms, which will generate a framework for predicting the consequences of future climate change and extreme temperatures for the conservation of aquatic species in Canada.