Environmental genomics of adaptive phenotypic plasticity for temperature in threespine stickleback (Gasterosteus aculeatus)

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How will organisms respond to future climate change? Scenarios include altered species' ranges, migration, extinction and adaptation. One form of adaptation, 'adaptive phenotypic plasticity', occurs when an organism has the ability to alter its phenotype (its internal or external characteristics) to match a changing environment such that it remains productive in each environment. Recent studies suggest that non-plastic populations will have a more difficult time coping with climate change than plastic populations. Although adaptive phenotypic plasticity could therefore be an important factor in maintaining future biodiversity, little is known about how it works on a genomic level. The threespine stickleback is an ideal model organism for studying the genes that are selected for plasticity. Marine populations of stickleback in Alaska and BC invaded freshwater after the last glacial maximum (approximately 12 000 years ago) and experienced higher high and lower low temperatures than in the marine environment. By raising marine and freshwater stickleback at different temperatures and using powerful genomics tools (microarrays and reverse genetics), we can not only determine whether selection has increased the plastic ability of freshwater populations, but we can identify the number and location of the genes responsible. Furthermore, an invasive stickleback population colonized Alberta 40 years ago. By comparing plasticity between the invasive population and its source of origin, we can further narrow in on those genes responsible for adaptive phenotypic plasticity. This research will determine the overall genomic effects of phenotypic plasticity on fish performance, and will elucidate the role that plasticity has played in enabling fish to persist in a changing environment. By studying the genetics of adaptive phenotypic plasticity in stickleback, we gain critical insight into how Canada's biodiversity will be affected in light of future climate change.