Individual and population level variation in physiological response to environmental change in Pacific salmon: mechanisms for local adaptation

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Declines in abundance of economically important species of Pacific salmon have been attributed to the interplay of a wide range of factors, including environmental changes in both freshwater and marine environments and past management practices. Changes in environment, therefore, are likely to negatively affect populations of salmon. Homing behaviour to specific locations isolates populations of salmon and has led to selection of locally adapted traits that influence fitness. Studying diversity among populations is important for understanding the evolution of local adaptations, which in turn can inform conservation decisions for restoration efforts or aquaculture purposes. Relationships between local adaptations and physiological function have been demonstrated, and locally adapted physiological traits are linked to genetic differences. Temperature has pervasive effects on biological systems and is particularly important in establishing the distribution and abundance patterns for animals, but particularly ectothermic animals. For species with large geographic distributions, considerable differences in thermal tolerance are likely to exist, but such patterns have not been adequately determined. Additionally ecosystem changes in response to climate change are linked to shifts in geographical distribution, migration failure, and alterations in seasonal timing of biological events - changes largely driven by environmental temperature. The objective of my proposed research program is to determine the effect of environment, particularly temperature, on physiological performance of salmon and how performance may differ among populations adapted to different geographic locations. For this examination I will target two life stages where generally high rates of mortality have been observed: the incubation period and the migration from freshwater to seawater. This research will provide us with an understanding of the physiological and molecular responses of salmon to temperature changes in their environment, findings that are particularly important given the localized effects of many environmental disturbances on temperature and the expected pervasive effects of global climate change.