Mountain building, climate cooling and the richness of cold-adapted plants in the northern hemisphere

Aim The summits of mountain ranges at mid-latitude in the Northern Hemisphere and the Arctic share many ecological properties including comparable climate and similar floras. We hypothesise that the orogeny during the Oligocene-Miocene combined with global cooling allowed the origin and early diversification of cold-adapted plant lineages in these regions. Before establishment of the Arctic cryosphere, adaptation and speciation in high elevation areas of these mountains ranges may have led to higher species richness when compared to the Arctic. Subsequent colonisation from mid-latitude mountain ranges to the Arctic may explain similar but poorer flora. Location Arctic-Alpine regions of the Northern Hemisphere. Methods We mapped the cold climate in the Northern Hemisphere for most of the Cenozoic (60 Ma until present) based on paleoclimate proxies coupled with paleoelevations. We generated species distribution maps from occurrences and regional atlases for 5464 cold-adapted plant species...