Linking plant genes to associated insect communities

Community genetics aims to link intraspecific genetic variation in one organism to the diversity and composition of communities of interacting organisms. For example, plant genetics have been shown to shape the communities of insects that colonize plants. However, the particular plant genes involved have not been identified. To address this void, we established a genetic mapping population (“WisAsp”) of 515 aspen (Populus tremuloides) replicated genotypes to identify the genes that influence communities of associated insects. We have found substantial variation in insect abundance across trees at WisAsp (from 0 to 631 insects/tree) as well as substantial variation in insect community composition across aspen genotypes at a nearby garden with a subset of nine genotypes from WisAsp (PerMANOVA F = 2.02, P < 0.002). We have also documented substantial genotypic variation in multiple tree traits that influence insects, including phytochemistry, bud phenology, tree growth, and extra floral nectaries. Next, we will use genome-wide association (GWA) to identify the genes in aspen that underlie variation in tree traits and insect community composition. Finally, we will evaluate the relative effects of aspen genetics and potential ecological interactions between insect species (e.g., competitive exclusion) in structuring insect communities. This work will provide fundamental insights into plant-insect interactions in a natural, community context and shed light on potential mechanisms of plant-insect evolution, community evolution, and the genetic underpinnings of trophic interactions.