|St. Clair, J. Bradley|
Submitted to: Evolutionary Applications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/16/2013
Publication Date: 6/21/2013
Citation: St. Clair, J., Kilkenny, F., Johnson, R.C., Shaw, N., Weaver, G. 2013. Genetic variation in adaptive traits and seed transfer zones for Pseudoroegneria spicata (bluebunch wheatgrass) in the northwestern United States. Evolutionary Applications. Evol. Appl.: doi:10.1111/eva.12077. Interpretive Summary: Results from this study indicate that populations of bluebunch wheatgrass (Pseudoroegneria spicata), a key rangeland restoration species, differed in traits important for adaptation. Several traits, particularly those associated with size, flowering phenology and leaf width, showed considerable population variation when populations were grown together in a common environment. Furthermore, that variation was related to the climates of seed sources in ways that made sense for survival, growth and reproduction. Seed zones that take into account the different ecotypes across the landscape may help ensure that material used in restoration is adapted to climates at the restoration sites. We recommend, however, the establishment of reciprocal transplant studies to better evaluate the adaptation of ecotypes as indicated by our proposed seed zone delineation.
Technical Abstract: A genecological approach was used to explore genetic variation in adaptive traits in Pseudoroegneria spicata, a key restoration grass, in the intermountain western United States. Common garden experiments were established at three contrasting sites with seedlings from two maternal parents from each of 114 populations along with five releases commonly used in restoration. Traits associated with size, flowering phenology and leaf width varied considerably among populations and were moderately correlated to the climates of the seed sources. P. spicata populations from warm, arid source environments were smaller with earlier phenology and had relatively narrow leaves than those from mild climates with cool summers, warm winters, low seasonal temperature differentials, high precipitation, and low aridity. Later phenology was generally associated with populations from colder climates. Releases were larger and more fecund than most of the native ecotypes, but were similar to native populations near their source of origin. Differences among native populations associated with source climates that are logical for survival, growth and reproduction indicate that genetic variation across the landscape is adaptive and should be considered during restoration. Results were used to delineate seed transfer zones and population movement guidelines to ensure adapted plant materials for restoration activities.