The Capacity of Populations to Respond to Climate Change

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Climate change has the potential to reshape patterns of biodiversity on a global scale. Despite widespread recognition of these concerns, researchers are still trying to answer the central question: do populations have the capacity to respond to climate change or will they go extinct? Projected temperature increases are likely to be especially challenging for ectothermic species – those that rely on external heat sources to control body temperature – because of the many effects that temperature has on the biology of these organisms. Thermal performance defines the relationship between an individual’s body temperature and fitness, and can be used as a framework for understanding the current geographical distributions of ectothermic species, and to predict the vulnerability of species to climate change. My research program will specifically assess the thermal performance of the cardiorespiratory system and its capacity to respond to climate change in both tropical and temperate fishes. The cardiorespiratory system is expected to be tightly linked to fitness in fishes, and its failure under heat stress may be a leading factor affecting population viability. My lab will detail both the responses of individuals exposed to higher temperatures during their lifetime (“phenotypic plasticity”) and the potential genetic responses of populations over evolutionary time (“adaptive potential”). My lab will also work to understand the mechanistic basis of variation in thermal performance by studying the contributions of heart morphology and mitochondrial efficiency to the upper temperature limits at which heart function collapses. Using experimental microcosms, we will provide a critical test of the hypothesized relationship between thermal performance traits and fitness, and thereby characterize the strength of selection acting on these traits. I will further monitor the evolution of thermal performance traits at elevated temperatures for multiple generations, measuring changes in adaptive potential and phenotypic plasticity and using a genomics approach to identify specific candidate genes associated with adaptation. These data will address gaps in our understanding of thermal performance, and are critical to construct predictive models of population and species extinction risk based on climate change scenarios. My lab will continue to work with decision-makers in government to incorporate these data and predictions into policy, particularly around the management of salmon, which are economically and socially important fishes to Canadians. My research program will thus address questions at the forefront of climate change research, and will provide a training environment that will allow my students to find employment in diverse sectors including academics, government and industry.