Results
Montane communities did not differ from the regional species pool in
terms of richness patterns, occupied climatic niche space, or niche
breadth. In contrast, alpine communities were characterized by a bimodal
latitudinal diversity gradient, drastically reduced climatic niche
space, and broader temperature but narrower precipitation niche breadth.
Alpine generalists further showed statistically significant differences
in temperature, but not precipitation, niche breadth from both alpine
specialists and lowland taxa. We also highlight non-alpine species whose
climatic niche space otherwise overlapped with that of alpine plants.
These species were geographically concentrated in the southern US and
Mexico, tended to have a greater fraction of their ranges in
frost-exposed mountain foothills, and less of their range in lowland,
frost-free, areas, compared to other non-alpine species.