Figure 2 . Species richness across the Americas for (a )
all seed plants; (b ) only montane species; (c ) only alpine
species; (d ) non-alpine species whose ranges overlapped with the
same temperature and precipitation conditions as alpine species.
Overall, seed plant diversity (including solely lowland species) and
montane-only communities followed traditional latitudinal richness
gradients, peaking near the equator. Alpine communities (panel
c ), however, had their greatest diversity in the western North American
cordillera and the central Andes. (d ) Non-alpine species whose
ranges were otherwise climatically similar to alpine species showed the
greatest concentration in Mexico and the southern United States (see
Discussion). (Warmer [cooler] colors indicate greater
[lower] species richness. Foreground: Mountain areas defined
by the Global Mountain Biodiversity Assessment [GMBA; see Methods].Background: non-mountainous areas in the sampling region. Grey
cells: missing or insufficient data. )