The relationship between evolvability and plasticity under experimental warming across species' elevational ranges

Phenotypic variation among individuals of a population arises from genetic and environmental effects. These may be correlated if they have similar underlying developmental mechanisms or selection histories. We tested empirically for such links over elevation gradients, on which species typically encounter predictable niche limits, range limits, and limits to adaptive evolution. We exposed plants from the elevational core and range edges of three montane and three alpine Brassicaceae species to experimental warming and measured key ecological traits that are divergent over elevation. Plasticity in these traits did not vary over elevational gradients, but populations with stronger multivariate plasticity had higher multivariate evolvability. Furthermore, the genetic covariance (G-)matrices of alpine species were less aligned with plasticity compared with those of montane species. Similar results were found between upper-edge as compared to core and lower-edge populations, though to a weaker extent. Moreover, plasticity to warming could have a cost, but slightly less so in alpine species. In summary, we provide evidence that populations that show greater environmentally induced variation also have higher evolvability independent of the position of populations along the elevational gradient. Yet, misalignment of plasticity particularly with selection indicates that plasticity may constrain persistence of montane and alpine plants under ongoing climate change.