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Abstract
Heterogenous environmental pressures can produce locally adapted populations which have higher fitness in their local environment compared to those from outside environments. Local adaptation is widespread throughout nature; however, we know less about the evolutionary mechanisms and processes that contribute to local adaptation. Climate change threatens to disrupt local adaptation by exposing plant populations to novel combinations of environmental stress. In this dissertation, I investigate the effects of a multifactorial manipulation of [CO2] and temperature on fitness and ecophysiological traits. I demonstrate that future climates will shift the fitness landscape and disrupt local adaptation. I also utilize natural accessions of Boechera stricta to conduct a series of genome-environment associations and genome-wide associations to investigate the genetic basis of local adaptation and find loci linked to climate, fitness and ecologically relevant traits. These results show genes related to abiotic stress response underly local adaptation and that fitness responses are context dependent at the genomic level. My results illustrate that local adaptation is driven by both trade-offs and conditionally neutral loci at the genomic level. Finally, I utilize phenotypes from the multifactorial growth chamber experiment to identify genetic components related to foliar traits. These results show anthocyanin responsesto temperature and [CO2] stress may also be associated with genes controlling herbivore resistance. Overall, my results make significant contributions to our understanding of the genetic basis of local adaptation in Boechera stricta and inform our understanding of how populations may respond to future environmental changes.