Abstract
The distribution of ‘cold-adapted’ plant species is expected to
undergo severe range loss in the next future. Species distribution
models predicting species’ future distribution often do not integrate
species ability to respond to environmental factors through genetic
traits or phenotypic plasticity. This especially applies to
arctic-alpine species whose present-day range is strongly fragmented
because of the cyclic vicissitudes they experienced during the Ice Age.
We cultivated plants from four European populations of the arctic-alpine
species Viscaria alpina from different geographic provenances.
Two of the populations were from northern high-latitude regions in
Scandinavia; the remainder two populations were from southern
mid-latitude mountains. In both areas one population was from a colder
site and the other from a warmer site. We cultivated the plants in
controlled thermal conditions with two treatments, the one mimicking
temperature conditions at the warmest site and the other adding two
day-temperature peaks mimicking short-term heat waves. At the end of the
experiment, we measured growth in length and mortality of all plants
along with a set of ecophysiological variables. We also
assessed genetic variation in the four populations based on plastid-DNA
sequences. The plants from northern provenances grew more than those
from the southern provenances. The plants of all populations performed
overall well, in terms of growth rate and ecophysiology, under the heat
spell with the plants of the Swedish population exhibiting the highest
phenotypic plasticity. Such pattern was associated with highest genetic
variation in the Swedish population. Mortality of the plants cultivated
under warm temperatures was overall low, but mortality strongly
increased in the plants exposed to the heat spell. We conclude that
plants of V. alpina populations from different geographic
provenances are generally able to cope with scenarios resulting from
global warming but drought hampers resilience to heat waves through
increased mortality.