PARENT SESSION
Poster Session #19: Invasive Species Ecology: Deserts and Rangelands.
Tuesday, August 6. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC
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Population genetics of cheatgrass in select areas of the Great Basin.
Ramakrishnan, Alisa*,1,2, Meyer, Susan2, Coleman, Craig1, Fairbanks, Daniel1, 1 Brigham Young University, Provo, UT2 USDA Forest Service Shrub Sciences Laboratory, Provo, UT
ABSTRACT- Bromus tectorum (cheatgrass) is an invasive weed common to rangelands in the western United States. We used six polymorphic microsatellite loci to analyze four populations (Potosi Pass, NV, Whiterocks, UT, Hobble Creek, UT, and Strawberry Reservoir, UT). These populations were chosen because they have previously been used to study cheatgrass phenotypic variation. Each locus amplified from three to six alleles. We sampled a total of 248 individuals and found 43 genotypes with no heterozygotes. The low level of heterozygosity is due to obligate inbreeding. Only one genotype was common to all three Utah populations, and it was found at a frequency of 16%-34%. The most frequent Utah genotypes were found in two of the three populations. However, they were usually very common in one population and only slightly represented in another. Whiterocks, with the most variable environment, also had the greatest number of genotypes (23). The Nevada site has low environmental variability and has a warmer mean annual temperature the three Utah sites. The major genotype of the Nevada population (75%) was unique among our samples. In order to generate as much polymorphism as we have observed, it is likely that cheatgrass has been introduced multiple times and that different genotypes of cheatgrass are pre-adapted to survive in different environments. Similar studies may allow us to estimate rates of introduction, susceptibility of a site to invasion due to environmental characteristics, and resistance polymorphism of cheatgrass to biological control methods.
KEY WORDS: Bromus tectorum, microsatellites, population genetics, invasive plants