Grant: Discovery Grants Program - Individual

What happens to the boundaries between species following cross-species mating or hybridization? Can hybridization sometimes contribute to the formation of new adaptations or to increase the invasiveness of weedy species?  More generally, what makes a plant invasive? These are the basic biological questions we will tackle.  The project will focus on the plant family Compositae, which is one of the most important families of flowering plants and includes many important crops and weeds. We will analyze the effects of hybridization on barriers that prevent the movement of genes between wild sunflower species.  Evolutionary biologists once believed that for species to form, barriers to gene flow must be absolute.  However, it now appears that some parts of the genome may be protected from interspecific gene flow, while others are not.  A fundamental question to be addressed by this proposal concerns the degree of protection provided by individual "speciation" genes. Hybridization between species is also sometimes viewed as a stimulus for rapid evolutionary change and possibly the evolution of invasiveness. We will identify hybrid combinations of traits and genes that have facilitated range expansion and the evolution of invasiveness of the common sunflower. Finally, building on a database of genes for the Compositae, we will compare the genomes of invasive and non-invasive populations of Russian knapweed, yellow star-thistle, common sunflower, and blueweed. We will search these genomes for signs of recent strong selection, a "footprint" of the evolution of invasiveness. Genetic changes associated with invasiveness will be characterized and their effects on fitness will be assessed in the field.