Evolutionary responses to climate change in a range expanding plant

Abstract

To understand the biological effects of climate change, it is essential to take into account species’ evolutionary responses to their changing environments. Ongoing climate change is resulting in species shifting their geographical distribution ranges poleward. We tested whether a successful range expanding plant has rapidly adapted to the regional conditions in its novel range, and whether adaptation could be driven by herbivores. Furthermore, we investigated if enemy release occurred in the newly colonized areas and whether plant origins differed in herbivore resistance. Plants were cloned and reciprocally transplanted between three experimental sites across the range. Effects of herbivores on plant performance were tested by individually caging plants with either open or closed cages. There was no indication of (regional) adaptation to abiotic conditions. Plants originating from the novel range were always larger than plants from the core distribution at all experimental sites, with or without herbivory. Herbivore damage was highest and not lowest at the experimental sites in the novel range, suggesting no release from enemy impact. Genotypes from the core were more damaged compared to genotypes from newly colonized areas at the most northern site in the novel range, which was dominated by generalist slug herbivory. We also detected subtle shifts in chemical defenses between the plant origins. Genotypes from the novel range had more inducible defenses. Our results suggest that plants that are expanding their range with climate change may evolve increased vigor and altered herbivore resistance in their new range, analogous to invasive plants.Electronic supplementary materialThe online version of this article (doi:10.1007/s00442-017-3864-x) contains supplementary material, which is available to authorized users.

Rapid growth and defence evolution following multiple introductions

“…Although analysis of neutral markers suggests genetic drift has been particularly strong in Australia (van Boheemen et al, 2017), we did not reveal any increase in inducible variation. The growing body of literature testing constitutive versus inducible defence in native and introduced ranges frequently report inconsistent results varying from reductions, to maintenance, to increases in either defence (Agrawal et al, 2015;Beaton, Zandt, Esselman, & Knight, 2011;Carrillo, Wang, Ding, Klootwyk, & Siemann, 2012;Cipollini & Lieurance, 2012;Cipollini et al, 2005;Eigenbrode et al, 2008;Fortuna et al, 2014;Gu et al, 2014;Macel et al, 2017;Wang et al, 2013Wang et al, , 2012 and calls for more detailed research on the cost-benefit trade-offs of the various responses.…”

Range-expanding plant species and their belowground neighbours : digging into novel interactions

“…We therefore cannot exclude that the strong defence against root-feeding nematodes by these related range-expanders is the result of natural selection during range expansion for genotypes that are especially well-defended against generalist herbivores (Doorduin & Vrieling 2011;Lin, Klinkhamer & Vrieling 2015). Future experiments using plant populations from both the original and the new ranges of the range-expanders are needed in order to examine whether such shifts in plant defence traits may have occurred during climate-driven range expansion (Macel et al 2017).…”

“…In North-western Europe, dozens of South-European plant species, e.g. Dittrichia graveolens, Rorippa austriaca and Tragopogon dubius, have become established or are expanding their range (Tamis et al 2005;van Grunsven et al 2010;Macel et al 2017;. Also urbanization may facilitate the establishment and expansion of plant species that previously occurred at lower latitudes as urbanized areas are often relatively warm and stony.…”

“…Due to this continued gene flow, populations in the expanded range may not be able to show strong evolutionary responses in response to their novel environment (Kirkpatrick & Barton 1997). However, recent studies showing natural selection during intracontinental range expansion (Macel et al 2017;) indicate that evolutionary responses should be considered when examining the novel interactions of climate-driven range-expanding plant species.…”

“…Range-expanders that are phylogenetically more distinct from native flora can be expected to have even stronger suppressive effects on these native natural enemies, but such evidence is lacking so far. Moreover, it is still largely unknown if the interactions between range-expanding plant species and their natural enemies differ between their original and new range as only a couple of studies (van Grunsven et al 2010;Dostálek et al 2015;Macel et al 2017) have addressed these questions experimentally.…”