Mechanisms underlying altitudinal and horizontal range contraction: The western black crested gibbon

Aim: Species ranges in mountain areas may shift both horizontally and altitudinally, resulting from climate change and anthropogenic impact. Two hypotheses (the abundant center hypothesis and the contagion hypothesis) have been proposed to account for patterns of horizontal range contraction. However, undulating topograph causes a mosaic of unsuitable habitats, which may complicate the spatial pattern of range contraction. We develop a framework incorporating horizontal and altitudinal range contraction patterns of a species living in mountain areas, to better understand the underlying mechanisms of species range contraction.

Location: China, North Laos, and North Vietnam

Taxon: Western black crested gibbon, Nomascus concolor

Methods: We collected occurrence data of the gibbons from various sources and modelled their potential distribution range in the 1950s, 1980s, and 2010s, using ecological niche modelling. We compared distances from the center point of the potential range i...