Tuesday, June 19, 2007 - 1:20 PM
Ponderosa Pines (Boise Centre on the Grove)

Ecological Genetics of Bromus tectorum (Cheatgrass, Downy Brome) in western North America

Cecilia Lynn Kinter, Idaho Conservation Data Center, Boise, ID

The Eurasian annual grass Bromus tectorum was introduced to the sagebrush steppe of western North America over 100 years ago. While historic records provide a few insights into the introduction and early dispersal of this pernicious weed, genetic analyses are currently providing much additional information. More than 10 genotypes now thrive in the North American range, and some of their potential source populations in western and central Europe have been identified from across the native range. Greenhouse comparisons show that genotypes now widespread in western North America have higher water use efficiency, photosynthetic capacity, and fitness when compared to genotypes from most native range populations, and populations that are not invasive in New Zealand. This higher performance appears to be due to establishment of certain native genotypes that are well-suited to the arid steppe, rather than to the evolution of novel genotypes following introduction to North America. Collectively, these studies indicate that future introduction of additional genotypes of Bromus tectorum from the native range could threaten areas not currently invaded by the grass.