Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: July 28, 2006
Publication Date: N/A
Interpretive Summary: Switchgrass is commonly used as a major component of seed mixes used to restore native tallgrass prairies in the USA. Although there is no scientific information on the topic, common thought among restoration ecologists is that seed should not be used any more than 100 miles or so from its point of origin. This study provides the first scientific information to verify that this value is unnecessarily small, that local switchgrass populations are remarkably similar across a broad geographic landscape. These results will be of value to restoration ecologists, conservationists, and plant geneticists.
Technical Abstract: Switchgrass is a perennial grass native to the North American tallgrass prairie and broadly adapted to the central and eastern USA. Movement of plant materials throughout this region creates the potential of contaminating local gene pools with genes that are not native to a locale. The objective of this study was to determine if importation of non-local populations in the northern and central USA has significant potential to contaminate local gene pools contained at prairie-remnant sites. Forty-six prairie-remnant populations and 11 cultivars were analyzed for random amplified polymorphic DNA (RAPD) markers. Although there was significant population differentiation, little of this variation was associated with geographic regions. There was very little spatial variability and only a small amount of variability was associated with geographic distance, providing only weak support for isolation by distance. A small amount of population differentiation was associated with hardiness zones and ecoregions, suggesting that a recent proposal to use these two criteria for defining plant adaptation regions has merit for defining restoration seed zones of switchgrass. Cultivars of switchgrass cannot be differentiated from prairie-remnant populations on the basis of RAPD markers, indicating that they are still highly representative of natural germplasm. Seed sources of switchgrass can be moved considerable distance within hardiness zones and ecoregions without causing significant contamination, pollution, swamping, or erosion of local gene pools.