Cheatgrass Genetic Varation in Montane Regions of the US Intermountain West

Cheatgrass (Brumus tectorum) is a highly invasive winter annual grass that now dominates millions of hectares of primarily sagebrush steppe habitat in the Intermountain Western regions of the United States.  The high volume of cheatgrass is a hazard due to its displacement of natural flora and fauna and its role as a major fuel in rangeland fires.  Although cheatgrass previously was found primarily in mid-elevation habitats, it has recently begun to expand into higher elevation montane regions.  Understanding the reasons for this secondary expansion of cheatgrass is necessary for better prevention of habitat destruction and wildfire risk.  Studies using SSR markers suggest that montane cheatgrass populations are genetically distinct from mid-elevation populations.  In order to perform a deeper study of these differences, we have used single nucleotide polymorphism (SNP) markers, previously developed in a study of mid-elevation populations, to analyze the genetic structure of montane cheatgrass populations. We hypothesize that the genetic make-ups of montane populations are similar to each other but different from mid-elevation populations.  Using 71 SNP markers, 19 populations have already been analyzed.  Results showed that plants from elevations above 6800 feet are genetically distinct from plants of lower elevations.  9 common haplotypes were found in these montane populations.  These haplotypes were divided into 4 haplogroups.  The existence of these haplogroups suggests that several cheatgrass genotypes adapted to montane habitats from native ranges in Europe and Asia.