title: Intraspecific variation of a dominant grass and local adaptation in reciprocal garden communities along a US Great Plains' precipitation gradient: implications for grassland restoration with climate change.
abstract: Identifying suitable genetic stock for restoration often employs a 'best guess' approach. Without adaptive variation studies, restoration may be misguided. We test the extent to which climate in central US grasslands exerts selection pressure on a foundation grass big bluestem (Andropogon gerardii), widely used in restorations, and resulting in local adaptation. We seeded three regional ecotypes of A. gerardii in reciprocal transplant garden communities across 1150 km precipitation gradient. We measured ecological responses over several timescales (instantaneous gas exchange, medium-term chlorophyll absorbance, and long-term responses of establishment and cover) in response to climate and biotic factors and tested if ecotypes could expand range. The ecotype from the driest region exhibited greatest cover under low rainfall, suggesting local adaptation under abiotic stress. Unexpectedly, no evidence for cover differences between ecotypes exists at mesic sites where establishment and cover of all ecotypes were low, perhaps due to strong biotic pressures. Expression of adaptive differences is strongly environment specific. Given observed adaptive variation, the most conservative restoration strategy would be to plant the local ecotype, especially in drier locations. With superior performance of the most xeric ecotype under dry conditions and predicted drought, this ecotype may migrate eastward, naturally or with assistance in restorations.
authors.affiliation: Biology, Kansas State University Manhattan, KS, USA.
authors.forename: Loretta C
authors.initials: LC
authors.lastname: Johnson
authors.affiliation: Department of Biological Sciences, Fort Hays State University Hays, KS, USA.
authors.forename: Jacob T
authors.initials: JT
authors.lastname: Olsen
authors.affiliation: Biology, Kansas State University Manhattan, KS, USA.
authors.forename: Hannah
authors.initials: H
authors.lastname: Tetreault
authors.affiliation: Biology, Kansas State University Manhattan, KS, USA.
authors.forename: Angel
authors.initials: A
authors.lastname: DeLaCruz
authors.affiliation: Biology, Kansas State University Manhattan, KS, USA.
authors.forename: Johnny
authors.initials: J
authors.lastname: Bryant
authors.affiliation: Biology, Kansas State University Manhattan, KS, USA.
authors.forename: Theodore J
authors.initials: TJ
authors.lastname: Morgan
authors.affiliation: Department of Agronomy, Kansas State University Manhattan, KS, USA.
authors.forename: Mary
authors.initials: M
authors.lastname: Knapp
authors.affiliation: Statistics, Kansas State University Manhattan, KS, USA.
authors.forename: Nora M
authors.initials: NM
authors.lastname: Bello
authors.affiliation: Plant Biology and Center for Ecology, Southern Illinois University Carbondale, IL, USA.
authors.forename: Sara G
authors.initials: SG
authors.lastname: Baer
authors.affiliation: Department of Biological Sciences, Fort Hays State University Hays, KS, USA.
authors.forename: Brian R
authors.initials: BR
authors.lastname: Maricle
keywords: Andropogon gerardii; Great Plains grasslands; abiotic stress; competition; drought; ecotypic variation; grassland restoration; local adaptation; reciprocal gardens