Plasticity in native perennial grass populations: Implications for restoration

Authors: Espeland, Erin; Johnson, Richard; HORNING, MATT - Forest Service (FS)

Submitted to: Evolutionary Applications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/10/2017
Publication Date: 2/27/2018
Citation: Espeland, E.K., Johnson, R.C., Horning, M.E. 2018. Plasticity in native perennial grass populations: Implications for restoration. Evolutionary Applications. 11(3):340–349. https://doi.org/10.1111/eva.12560.
DOI: https://doi.org/10.1111/eva.12560

Interpretive Summary: Plasticity is the plant’s response to its environment. The phenotype of a plant (its size, leaf shape, date of onset of flowering) is typically an interaction between genetics and environmental cues. Research has shown that plasticity (or, a plant’s ability to respond to the environment) increases the probability that populations will persist under climate change, and it also increases the population’s evolutionary potential. When choosing plant materials for restoration, selecting seed genetically adapted to the restoration environment is critical for success, but plasticity may also contribute to establishment and persistence in disturbed environments. Do some seed source environments maintain more plastic genotypes than others? In Poa secunda, collected from 130 places across the west, we measured plant phenotypes in two common gardens over two growing seasons. Seeds collected from warm and dry locations produced plants with higher plasticity in phenology (timing of reproductive events), panicle number, and biomass; cool and wet sources had higher plasticity in leaf size, panicle length, plant habit (prostrate or erect), and survival. The magnitude of plasticity was greater in plants from seeds collected from warm and dry environments. These results indicate that the benefit of plasticity depends on the growing environment and may depend in the phenotypic trait in question.

Technical Abstract: Increasing the evolutionary potential of restored populations is a recently-accepted objective of restoration activities. Choosing plant materials genetically adapted to the restoration environment is critical for success, but phenotypic plasticity may also contribute to establishment and persistence in disturbed environments. To source seeds for restoration that harbor plasticity, we must answer the question: do some provenances produce more plastic genotypes than others? Using a genecology dataset of 260 maternal families from 130 western U.S. source populations (provenances) of the perennial bunchgrass Poa secunda, we determined the contribution of source population to phenotypic plasticity in two common gardens over two growing seasons. Compared with the genetic contribution to the phenotype, plasticity explained a higher fraction of phenotypic variation and was particularly strong for phenology traits. For the morphological traits panicle length, leaf size, and survival, the genetic contribution to the phenotype was greater than the plastic contribution. Seeds collected from warm and dry provenances produced plants with higher plasticity in phenology (timing of reproductive events), panicle number, and biomass; cool and wet provenances had higher plasticity in leaf size, panicle length, plant habit (prostrate or erect), and survival. Because of opposing patterns of genetic variation and plasticity (when one is higher the other is lower), plasticity may contribute as much or more than genetic factors to adaptation in restoration materials in some traits. There is tremendous potential to use genecology datasets to understand general patterns of plasticity and apply this knowledge to plant materials selection.