Limited evidence for range-shift-driven extinction in mountain Biota

Mountain biodiversity is rapidly reorganizing as species migrate upslope
to track climate warming. Despite the potential threats of mountaintop
extirpation, range shift gaps, and lowland biodiversity attrition,
empirical evidence of these risks remains scarce. We analyzed 8,800
records of historical and modern elevational range limits for 440 animals
and 1,629 plant species and found that the risk of mountaintop extirpation
did not exceed random expectations. Upper limits expanded for species with
narrow ranges or lowland affinities, but lower limits showed little
contraction, implying scant risk to date of these threats, even in the
tropics. Yet the predominance of upslope expansion combined with delayed
mountaintop extirpations points to a biotic homogenization, which may
profoundly alter biotic interactions in mountain ecosystems with
increasing warming.