Ecological Genomics of a Weedy Thistle

Invasive species offer both ample incentive and opportunity to address some of the major questions in evolution, ecology, and genetics. The direct costs of weed control and indirect costs of reduced crop production due to weeds are up to $40 billion annually in North America. Invasive species pose a major threat to biodiversity and ecosystem function, and are a major driver of global environmental change.  Rates of adaptive phenotypic change are high in human-disturbed contexts, such as invasion, and more common in introduced relative to native species in the same environment. Thus, an eco-evolutionary approach may reveal key insights into a species’ adaptive capacity in the face of human-induced selective pressures. Centaurea species (knapweeds, star thistles) comprise the most abundant noxious weed genus in the western United States. Native to parts of Eastern Europe, Centaurea diffusa was first reported in North America in 1907 and now occurs in more than half Canada and the US, where it can form dense monocultures, reducing forage quality, and altering soil and water resource availability. Here we report ongoing investigations into the ecological genomics of C. diffusa: 1) Denovo assembly using whole genome shotgun Illumina sequence of an individual from the native range (the first draft whole genome assembly of this species, and one of only seven plastid genomes in the Sunflower family); And 2) Comparisons of gene expression between native and invasive populations under control and drought treatment from NimbleGen microarrays.