Evolutionary genetics of genotype-by-environment interactions for complex traits

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PROJECT SUMMARY A key question in my research is: why does diversity in quantitative traits persist, despite evidence of selection that should eliminate this diversity? Environmental variation can generate genetic tradeoffs both among and within populations, helping to maintain this genetic diversity. I study the genetic mechanisms and architecture of these tradeoffs in nature. My recent research has focused on two central goals: 1) developing approaches for finding the genetic basis of local adaptation and 2) empirical testing of hypotheses about local adaptation and G×E. I propose research to study genetic mechanisms of adaptation to environment using a model system that is convenient for ecological experimentation, Arabidopsis thaliana. This work will test hypotheses about the genetic architecture of adaptation to changing environments through space and time, about how gene flow influences genetic architecture, and about the role of gene expression plasticity in adaptation to variable environments. In all projects, our ability to conduct ecologically realistic but controlled common garden experiments will provide information on genetic variation in environmental responses (G×E) that can be used to interpret observational data from nature. We will first study the genetic mechanisms of adaptation to temporally changing environments. We will study how different populations of have adapted to hundreds of generations of environmental change by sequencing genomes of museum specimens. Second, we will study local adaptation along montane environmental gradients with different levels of isolation to test how gene flow influences the architecture of local adaptation. This project will collect populations from different geographic contexts and conduct experiments to characterize the genetic basis of local adaptation and expression plasticity. My proposed work will make important strides in testing how tradeoffs along complex environmental gradients influence genetic diversity across the genome.