Data from: Local adaptation at range edges: comparing elevation and latitudinal gradients

Local adaptation at range edges influences species’ distributions and how
they respond to environmental change. However, the factors that affect
adaptation, including gene flow and local selection pressures, are likely
to vary across different types of range edge. We performed a reciprocal
transplant experiment to investigate local adaptation in populations of
Plantago lanceolata and P. major from central locations in their European
range and from their latitudinal and elevation range edges (in northern
Scandinavia and Swiss Alps, respectively). We also characterized patterns
of genetic diversity and differentiation in populations using molecular
markers. Range-centre plants of P. major were adapted to conditions at the
range centre, but performed similarly to range-edge plants when grown at
the range edges. There was no evidence for local adaptation when comparing
central and edge populations of P. lanceolata. However, plants of both
species from high elevation were locally adapted when compared with plants
from high latitude, although the reverse was not true. This asymmetry was
associated with greater genetic diversity and less genetic differentiation
over the elevation gradient than over the latitudinal gradient. Our
results suggest that adaptation in some range-edge populations could
increase their performance following climate change. However, responses
are likely to differ along elevation and latitudinal gradients, with
adaptation more likely at high elevation. Furthermore, based upon these
results, we suggest that gene flow is unlikely to constrain adaptation in
range-edge populations of these species.