Evidence of local adaptation to fine- and coarse-grained environmental variability in Poa alpina in the Swiss Alps

In the alpine landscape, characterized by high spatiotemporal heterogeneity and barriers, divergent selection is likely to lead to local adaptation of plant populations either through adaptive genetic differentiation or through phenotypic plasticity. The relative importance of these processes has rarely been investigated in relation to the spatial scale of environmental heterogeneity. In this study, we used reciprocal transplantation experiments of populations across nearby and distant field sites to shed light on these complementary processes.
We reciprocally transplanted populations of the widespread alpine grass, Poa alpina, within and across regions in the Swiss Alps. We inferred local adaptation at the metapopulation level by comparing fitness of plants transplanted to their site of origin and to nearby or distant novel sites. Additionally, we measured specific leaf area (SLA) and performed selection analyses to investigate directional selection on mean trait value at each field s...