Population structure and genetic diversity of within the small grain production region of the Pacific Northwest.

L. is an invasive winter annual grass naturalized across the United States. Numerous studies have investigated population structure and genetics in the context of as an ecological invader of natural areas and rangeland. Despite the wealth of information regarding , previous studies have not focused on, or made comparisons to, as it persists in individual agroecosystems. The objectives of this study were to assess the genetic diversity and structure, the occurrence of generalist and specialist genotypes, and the influence of climate on distribution of sourced exclusively from within small grain production regions of the Pacific Northwest. Genetic diversity of sourced from agronomic fields was found to be similar to what has been observed from other land use histories. Six distinct genetic clusters of were identified, with no evidence to indicate that any of the genetic clusters were better adapted to a particular geographical area or climate within the region. Given the apparent random spatial distribution of genetic clusters at the spatial scale of this analysis, unique genotypes may be well mixed within region, similar to what was reported for other inbreeding weedy grass species.