Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 6, 2011
Publication Date: November 1, 2011
Citation: Parsons, M.C., Jones, T.A., Larson, S.R., Mott, I.W., Monaco, T.A. 2011. Ecotypic variation in Elymus elymoides ssp. Brevifolius race C in the northern Intermountain West. Rangeland Ecology and Management. 64:649-658. Interpretive Summary: Bottlebrush squirreltail is a widespread rangeland species that exhibits great genetic diversity. Appropriate genetic material is needed to increase the likelihood of success of restoration plantings. Thirty-six accessions originating in the northern Intermountain West were characterized with DNA markers, plant traits measured in a common garden, and environmental data corresponding to their native sites. These three data sets were found to correspond with each other, suggesting that this group displays considerable ecotypic variation. Four adaptive zones were described that provide guidance for choosing seed sources for restoration efforts. This material from the northern Intermountain region merits description as a distinct subspecies of bottlebrush squirreltail instead of being lumped with ssp. brevifolius, which is found to the east in the Rocky Mountains and western Great Plains.
Technical Abstract: Bottlebrush squirreltail (Elymus elymoides [Raf.] Sweezey) is an important native bunchgrass for restoration of degraded rangelands of western North America. It is taxonomically complex and has diverged into as many as four subspecies, including ssp. brevifolius, for which four geographically distinct races have been described (A, B, C, and D). Because of the great genetic variation within this species, there is significant potential for site maladaptation when inappropriate genetic material is used for restoration applications. Our objectives were to assess genetic variation within race C, to identify groups of genetically and phenotypically similar populations within this race, and to develop preliminary adaptive zones to guide restoration efforts in the northern Intermountain West, USA. Research was conducted at the Utah State University Millville Research Farm, south of Millville, UT, and the USDA-ARS greenhouse on the campus of Utah State University, Logan, UT. We evaluated 32 populations of race C collected across the northern Intermountain West for phenotypic variation for a battery of biomass, phenological, and functional traits in common-garden settings in the field and greenhouse employing randomized complete block designs. Genetic variation was assessed using AFLP markers, and correlations were calculated among phenotypic, genetic, environmental, and geographical distance matrices using Mantel tests. Phenotypic, genotypic, environmental, and geographical distances were positvely correlated with one another. A multivariate analysis revealed that collection-site plant traits measured in a common garden were correlated with latitude, minimum temperature, elevation, maximum temperature, and longitude but not with average annual precipitation. The so-called race C merits description as a new subspecies. It displays considerable ecotypic variation, and the environment is shaping patterns of genetic and phenotypic divergence. We describe four geographically distinct preliminary adaptive zones that correspond to previously established ecoregions. Their implementation will facilitate the conservation of this taxon and provide appropriate genetic material for restoration efforts.