Data from: Exotic plant species are locally adapted but not to high UV‐B radiation: a reciprocal multi‐species experiment

Ultraviolet (UV) radiation intensities differ among global regions, with
significantly higher levels in the southern hemisphere. UV-B may act as an
environmental filter during plant invasions, which might particularly
apply to plant species from Europe introduced to New Zealand. Just like
for any other abiotic or biotic filter, successful invaders can cope with
novel environmental conditions via plastic responses and/or through rapid
adaptation by natural selection in the exotic range. We conducted a
multi-species experiment with herbaceous plants in two common gardens
located in the species’ ‘native’ and exotic ranges, in Germany and New
Zealand, respectively. We used plants of German and New Zealand origin of
eight species to test for adaptation to higher UV-B radiation in their new
range. In each common garden, all plants were exposed to three radiation
treatments: (i) ambient sunlight, (ii) exclusion of UV-B while
transmitting ambient UV-A, and (iii) combined exclusion of UV-B and UV-A.
Linear mixed-effect models revealed significant effects of UV-B on growth
and leaf traits and an indication for UV-B-induced biomass reduction in
both common gardens pointing to an impact of natural, ambient UV radiation
intensities experienced by plants in the northern and in the southern
hemisphere. In both common gardens, the respective local plants (i.e.
German origins in Germany, New Zealand origins in New Zealand) displayed
enhanced productivity and aboveground biomass allocation, thus providing
evidence for recent evolutionary processes in the exotic range. Genetic
differentiation between different origins in consequence of divergent
local selection pressures was found for specific leaf area. This
differentiation particularly hints at different selective forces in both
ranges while only little evidence was found for an immediate selective
effect of high UV-B intensities in the exotic range. However, reaction
norm slopes across ranges revealed higher plasticity of exotic individuals
in functional leaf traits that might allow for a more sensitive regulation
of photoprotection measures in response to UV-B. During the colonization,
New Zealand populations might have been selected for the observed higher
phenotypic plasticity and a consequently increased ability to successfully
spread in the exotic range.