Evolutionary history of the Arctic flora.

The Arctic tundra is a relatively young and new type of biome and is especially sensitive to the impacts of global warming. However, little is known about how the Arctic flora was shaped over time. Here we investigate the origin and evolutionary dynamics of the Arctic flora by sampling 32 angiosperm clades that together encompass 3626 species. We show that dispersal into the Arctic and in situ diversification within the Arctic have similar trends through time, initiating at approximately 10–9 Ma, increasing sharply around 2.6 Ma, and peaking around 1.0–0.7 Ma. Additionally, we discover the existence of a long-term dispersal corridor between the Arctic and western North America. Our results suggest that the initiation and diversification of the Arctic flora might have been jointly driven by progressive landscape and climate changes and sea-level fluctuations since the early Late Miocene. These findings have important conservation implications given rapidly changing climate conditions in the Arctic. The Arctic tundra is a relatively young biome. Here, the authors sample 32 angiosperm clades encompassing 3600+ species and find that both long-term dispersal and in situ speciation may have contributed to Arctic flora assembly, in association with landscape, climate and sea-level changes since the early Late Miocene. [ABSTRACT FROM AUTHOR]