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 ...