Plasticity in native perennial grass populations: Implications for restoration

Increasing the evolutionary potential of restored populations has become a viable objective of restoration activities. Choosing plant materials genetically adapted to the restoration environment is critical for success, and phenotypic plasticity may also contribute to establishment and persistence in disturbed environments. To select seed sources for restoration informed by plasticity, we must answer the question: Do some source environments produce more plastic genotypes than others? Using a dataset of maternal families from 130 western US source populations of the perennial bunch-grass Poa secunda, we used variance components to determine the contribution of source population to phenotypic plasticity in two common gardens over two growing seasons. Compared with the genetic contribution to phenotypes, plasticity explained a large fraction of phenotypic variation and was particularly strong for phenology (timing of reproductive events) traits. Plasticity values among phenology traits were also highly correlated. For the morphological traits (panicle length, leaf size) and survival, the genetic contribution to the phenotype was greater than the plastic contribution, but plasticity values among these traits were not highly correlated. Seeds collected from warm and dry locations produced plants with more plasticity in phenology, panicle number, and biomass; cool and wet locations were associated with more plasticity in leaf size, panicle length, plant habit (prostrate or erect), and survival. Plasticity may complement genetic variation for adaptation in restoration materials in some traits.