Environmental contributions to the evolution of trait differences inGeum triflorum: implications for restoration

Abstract

Premise of the Study: Understanding how environment influences the distribution of trait variation across a species range has important implications for seed transfer during restoration. Heritable genetic differences associated with environment could impact fitness when transferred into new environments. Here, we test the degree to which the environment shapes the evolution and distribution of genetic effects for traits important to adaptation. Methods: In a common garden experiment, we quantified trait differentiation for populations of Geum triflorum sourced from three distinct ecoregions and evaluated the ability of climate to predict trait variation. Populations were sourced from alvar ecoregions which experience predictable extremes in seasonal water availability and the prairie ecoregion which exhibits unpredictable changes in water availability. Key Results: Plants sourced from alvar ecoregions exhibited smaller but more numerous stomata and greater intrinsic water use efficiency relative to prairie plant populations supporting the evolution of ecotypic differences. Estimates of standing genetic variance and heritable genetic variation for quantitative traits suggest alvar populations have greater adaptive potential. However, reduced evolvability suggest all populations of G. triflorum may have limited capacity to evolve in response to environmental change. Conclusions: These results point towards the importance of understanding the role of environment in shaping the distribution and evolution of genetic differences across seed populations and how these data may inform recommendations for seed transfer across novel environments and our expectations of populations adaptive potential.

What determines the evolutionary trajectories of wild plant species? Approaches to the study of quantitative fitness‐related traits

“…Some common garden studies are conducted with the aim of using the expression of population differentiation and within‐population genetic variation in functional traits to inform decisions regarding the provenance of seeds to be used in restoration efforts. Here, Volk et al (2022) used a common garden experiment to explore physiological trait differentiation among 22 populations of the perennial Geum triflorum (prairie smoke; Rosaceae) sampled from the thin‐soiled alvar ecoregions of the Great Lakes and Manitoba (characterized by predictable extremes in seasonal water availability) and from the prairie ecoregion (where populations experience unpredictable water availability). The patterns observed hold implications for the adaptive potential of populations of seeds sampled from these regions when introduced to novel sites targeted for restoration.…”

“…In this issue, common gardens or reciprocal transplants were used to examine a broad array of fitness-related traits, including floral scent (Eisen et al, 2022;Campbell et al, 2022a), SLA, WUE, trichome density, and floral morphology (Campbell, 2022a), germination time (Muir et al, 2022), flowering time (Cheptou et al, 2022), and physiological traits (Volk et al, 2022). Campbell et al (2022a) combined variance component analysis with a common garden experiment comprising multiple generations to detect differentiation between taxa in floral vs. vegetative traits and to compare the current evolutionary potential of these traits in Ipomopsis aggregata (Polemoniaceae), I. tenuituba, and their hybrids raised in three common gardens.…”