Figure 1
Current and potential future patterns in functional dispersion (FDis) of frugivorous bird assemblages along an elevational gradient in the Peruvian Andes. Current patterns in bird assemblages are shown on the left (“current assemblages”) and expected changes under future climate change are shown on the right side of the mountain (“projected future assemblages”). Currently, low elevations harbour the highest FDis, and FDis decreases with increasing elevation. In the future, projected changes could include (i) losses of FDis at the lowest elevations, due to the emigration of functional specialists, (ii) a rather constant FDis at mid-elevations if species immigrating and emigrating are functionally similar, and (iii) species extinction at high elevations, due to a dispersal barrier beyond the tree line. Ranges of species can be constant, contract (a), expand (b) or shift (c) in response to projected climate change; black bird silhouettes indicate the presence of a species on an elevational level, species outlines indicate that a species moved out of the respective elevational level, and the dotted silhouette indicates species extinction from the entire gradient. The entire gradient covers an elevational range from lowland (250 m) up to the mountaintop (3750 m). Forests cover the mountain up to 3500 m (green shading) and the studied gradient covers 500–3500 m of elevation.
