Elevation drives intraspecific metabolomic differentiation in natural and experimental populations

A recent paradigm shift in ecology supports that the classic functional trait space should be extended to include the metabolome. Accordingly, metabolomic signatures differ between plant species or genotypes depending on where they grow along ecological gradients. Yet, it remains unclear whether environmental gradients alone induce intraspecific phytochemical shifts in natural populations, and if these differences can be replicated experimentally. To address this gap, we combined an observational and experimental study to explore how elevation drives differences in the diversity, endemism and composition of specialized metabolites within the widely distributed perennial grass Festuca rubra. We show that both natural and experimental populations (consisting of identical sets of unique genotypes) exhibit distinct metabolic profiles, unique to each elevation. While natural populations growing in alpine environments displayed lower phytochemical diversity and endemism than those inhabiting lower elevations, phytochemical diversity and endemism peaked at intermediate elevation for the experimental populations. In addition, elevation caused shifts in overall composition of metabolomic groups for experimental populations, reflected in alterations in the over- and under-representation of metabolites within specific superclasses. Our study demonstrates that elevation plays an important role in shaping the metabolome. Rapid shifts in abiotic and biotic environments following climate change may act to alter the plant metabolome, which can impact future ecosystem-level dynamics.