**Acknowledgments**

We are grateful for being allowed to reuse figures and tables from Arctic, Antarctic and Alpine Research (copyright by the Regents of the University of Colorado) and Scientific Reports (copyright by Nature Publishing Group). We thank Ole Wiggo Røstad for producing several figures, Oddvar Hanssen for photographing beetles, Steve J. Coulson for the photograph of *C. foveolata* and Valerie Behan-Pelletier for SEM photograph of *Camisia horrida*.
