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ARS Home » Plains Area » Temple, Texas » Grassland Soil and Water Research Laboratory » Research » Publications at this Location » Publication #389854
Research Project: Contributions of Climate, Soils, Species Diversity, and Management to Sustainable Crop, Grassland, and Livestock Production Systems

Location: Grassland Soil and Water Research Laboratory

Title: Correlational selection and genetic architecture shape the evolution of the leaf economics spectrum in a perennial grass

Author
item HECKMAN, ROBERT - University Of Texas At Austin
item JOHN, GRACE - University Of Florida
item BONNETTE, JASON - University Of Texas At Austin
item CAMPITELLI, BRANDON - University Of Texas At Austin
item FRITSCHI, FELIX - University Of Missouri
item LOWRY, DAVID - Michigan State University
item Fay, Philip
item JUENGER, THOMAS - University Of Texas At Austin

Submitted to: Proceedings of the National Academy of Sciences (PNAS)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/13/2026
Publication Date: 2/27/2026
Citation: Heckman, R., John, G.P., Bonnette, J., Campitelli, B., Fritschi, F.B., Lowry, D.B., Fay, P.A., Juenger, T. 2026. Correlational selection and genetic architecture shape the evolution of the leaf economics spectrum in a perennial grass. Proceedings of the National Academy of Sciences (PNAS). https://doi.org/10.1073/pnas.2515134123.
DOI: https://doi.org/10.1073/pnas.2515134123

Interpretive Summary: The leaf economics spectrum results from a trade-off between resource acquisition and conservation. In high resource environments, plants typically possess short-lived leaves with low structural costs and high nutrient content, while in low resource environments, plants often have long-lived leaves with high structural costs and low nutrient content. Despite strong evidence for the presence of the leaf economics spectrum at broad geographic and taxonomic scales, few studies have examined how this spectrum evolves. Here, we show in the candidate biofuel species, switchgrass, that leaf economics strategies could evolve through a combination of mechanisms: pairs of leaf economics traits (photosynthetic rate and nitrogen content) may be coded by the same genes and selection for particular, advantageous trait combinations (e.g., low nitrogen content and high leaf structural costs) and against other, deleterious combinations. Together, these evolutionary mechanisms can promote the evolution of distinct leaf economics strategies within different varieties of switchgrass. Understanding how switchgrass varieties with different trait combinations perform in various environments may improve our ability to breed more productive biofuel crops.

Technical Abstract: The leaf economics spectrum (LES) is hypothesized to result from a trade-off between resource acquisition and conservation. Yet few studies have examined the evolutionary mechanisms behind the LES, perhaps because most species exhibit relatively specialized leaf economics strategies. In a genetic mapping population of the phenotypically diverse grass Panicum virgatum, we evaluate two interacting mechanisms that may drive LES evolution: 1) genetic architecture, where multiple traits are coded by the same gene (pleiotropy) or by genes in close physical proximity (linkage), and 2) correlational selection, where selection acts non-additively on combinations of multiple traits. We found evidence suggesting that shared genetic architecture (pleiotropy) controls covariation between two pairs of leaf economics traits. Additionally, at five common gardens spanning 17 degrees of latitude, correlational selection favored particular combinations of leaf economics traits. Together, these results demonstrate how the LES can evolve within species.