ARS | Publication request: ARE CHEATGRASS POPULATIONS LOCALLY ADAPTED?

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 28, 2003
Publication Date: January 25, 2004
Citation: Longland, W.S., Ashley, M.C. 2004. Are cheatgrass populations locally adapted [abstract]? Society for Range Management, Salt Lake City, Utah, January 24-30, 2004. 57:44

Technical Abstract: Cheatgrass (Bromus tectorum) is an invasive annual grass that has become the most widespread weed species in arid western North America. Because cheatgrass is generally (and some claim obligately) self-pollinating, its spread to more extreme environments has been attributed to multiple introductions of genetically distinct germplasm or phenotypic plasticity. However, we have found ample evidence of infrequent outcrossing in cheatgrass, suggesting that its spread may be attributable to local adaptation through genetic recombination. Reciprocal planting experiments in the greenhouse provide some evidence of adaptation to local soil conditions. Cheatgrass seeds from four sites planted in a full factorial design in soils from the same sites produced the most robust plants and the greatest number of seeds when grown in the local soil or a similar soil type. Genetic screening (using RAPDs) of a cheatgrass population sampled annually after its initial invasion into a sand dune environment revealed much higher than expected genetic variation immediately after the invasion, which is consistent with expectation if the invasion was facilitated by heterosis. Local adaptation indeed appears to offer a viable mechanism through which cheatgrass has dominated a wide range of environments across an entire region.