Dissertation Research: Climate change and candidate gene variation in Populus: Impacts on dependent communities and biotic interactions

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This research will examine how climate drives patterns of genetic variation in cottonwoods and how this variation affects organisms dependent on cottonwood. Using replicated common gardens from Arizona to Alberta, genetically based variation in growth, survival, and timing of growth initiation and cessation (key adaptive traits for forest trees) among tree populations from a latitudinal gradient will be measured. With the replicated gardens spanning a broad climatic range, investigations of how temperature and precipitation interact with genetic variation to influence tree traits and to determine if trees are adapted to their local environments will be conducted. Using molecular tools, climate's effect on specific genes that influence the timing of growth initiation and cessation will be quantified. These traits can also strongly influence dependent insect herbivores. Therefore, surveys of insects feeding on the cottonwood trees, determining how genetic variation in the trees affects dependent organisms will also be conducted.This research will have broader significance in five main ways. First, if tree populations are currently locally adapted to their environmental conditions, future climate change could render populations locally maladapted. Thus, understanding patterns of adaptation and genetic variation in trees is needed to understand the potential impact climate change will have on natural systems. This information will aid resource managers when undertaking restoration projects, common in riparian areas throughout the country. Second, understanding how genetic variation influences interactions among species is a frontier of ecology and evolutionary biology. This work will extend that frontier by identifying genes underlying traits that have consequences for biotic communities. Third, graduate student's research will promote science education by training an undergraduate assistant in field and laboratory techniques. Fourth, this study will establish a long-term international collaboration with researchers in Canada and the United States. Finally, this grant will initiate a long-term field experiment, necessary to fully understand effects of climate change on biotic communities.