Local adaptation to precipitation in the perennial grass Elymus elymoides: Trade-offs between growth and drought resistance traits

Authors: Blumenthal, Dana; Lecain, Daniel; Porensky, Lauren; LEGER, ELIZABETH - University Of Nevada; Gaffney, Rowan; OCHELTREE, TROY - Colorado State University; PILMANIS, ADRIENNE - Former ARS Employee

Submitted to: Evolutionary Applications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2020
Publication Date: 9/21/2020
Citation: Blumenthal, D.M., LeCain, D.R., Porensky, L.M., Leger, E., Gaffney, R.M., Ocheltree, T., Pilmanis, A. 2020. Local adaptation to precipitation in the perennial grass Elymus elymoides: Trade-offs between growth and drought resistance traits. Evolutionary Applications. 14(2):524-535. https://doi.org/10.1111/eva.13137.
DOI: https://doi.org/10.1111/eva.13137

Interpretive Summary: Understanding local adaptation to climate is critical for restoring and managing rangeland ecosystems in the face of climate change. We measured growth potential and drought-resistance traits in 99 populations of the perennial grass bottlebrush squirreltail from a broad geographic and climatic range in the western United States. Plants from drier sites produced less biomass and smaller seeds, and had traits associated with greater drought resistance. Plants from regions with more Mediterranean climates, with relatively cool, dry summers, also had greater drought resistance. Irrespective of climate, we observed tradeoffs between biomass production and drought resistance traits, suggesting that ecotypes that grow rapidly may be less able to persist under dry conditions. Choice of appropriate germplasm for this common rangeland species should include explicit consideration of drought resistance, and the use of tools such as seed transfer zones to match traits to current and predicted climates.

Technical Abstract: Understanding local adaptation to climate is critical for managing ecosystems in the face of climate change. While there have been many provenance studies in trees, less is known about local adaptation in herbaceous species, including the perennial grasses that dominate arid and semiarid rangeland ecosystems. We used a common-garden study to quantify variation in growth and drought-resistance traits in 99 populations of Elymus elymoides from a broad geographic and climatic range in the western United States. Ecotypes from drier sites produced less biomass and smaller seeds, and had traits associated with greater drought resistance: small leaves with low osmotic potential and high '13C. Seasonality also influenced plant traits. Plants from regions with relatively warm, wet summers had large seeds, large leaves, and high '13C. Together, these results suggest that much of the phenotypic variation among E. elymoides ecotypes represents local adaptation to differences in the amount and timing of water availability. Irrespective of climate, we also observed tradeoffs between biomass production and drought resistance traits, suggesting that ecotypes that grow rapidly may be less able to persist under dry conditions. The future success of this common rangeland species will likely depend on the use of tools such as seed transfer zones to match local variation in growth and drought resistance to predicted climatic conditions.