Abstract
Phenotypic plasticity can mask population genetic differentiation,
reducing the predictability of trait-environment relationships. In
short-lived plants, reproductive traits may be more genetically
determined due to their direct impact on fitness, whereas vegetative
traits may show higher plasticity to buffer short-term perturbations.
Combining a multi-treatment greenhouse experiment with global field
observations for the short-lived Plantago lanceolata , we 1)
disentangled the genetic and plastic responses of functional traits to a
set of environmental drivers and 2) assessed the utility of
trait-environment relationshisps inferred from observational data for
predicting genetic differentiation. Reproductive traits showed distinct
genetic differentiation that was highly predictable from observational
data, but only when correcting traits for differences in their (labile)
biomass component. Vegetative traits showed higher plasticity and
contrasting genetic and plastic responses, leading to unpredictable
trait patterns. Our study suggests that genetic differentiation may be
inferred from observational data only for the traits most closely
related with fitness.