Geography and diet: phylogenetic and regional patterns in colobine plant use

Diet is fundamental to primate ecology, influencing behaviour, habitat use, and ecological adaptation. Dietary variation helps reveal how primates respond to environmental and evolutionary pressures. Colobines provide a particularly useful model for examining these patterns because of their foregut fermentation and predominantly plant-based diets. In this study, we present a global synthesis of colobine feeding ecology, comprising a standard dietary database from 76 studies, including 40 colobine species across ten genera. The dietary composition, plant life-forms use, and intergeneric dietary overlap were quantified by using nonmetric multidimensional scaling (NMDS), PERMANOVA, a Mantel test, and Pianka’s index. We found that across 914 recorded plant genera, only 0.6% contributed substantially (>1% of feeding records) to their diets, indicating an asymmetric use of a narrow subset of taxa, particularly Ficus , Syzygium , and Albizia . Trees dominated their diet, followed by shrubs and climbers. Nonmetric multidimensional scaling showed that African and Asian colobines have different diet compositions, with Asian colobines showing higher dietary variability. Dietary overlap was generally low: only 41.8% of plant genera were shared across multiple colobine genera, suggesting strong niche differentiation. However, closely related taxa showed higher overlap, such as Semnopithecus–Trachypithecus and Colobus–Piliocolobus , which is consistent with phylogenetic conservatism in food use. Niche similarity patterns were clustered mainly by biogeography, whereas Rhinopithecus stood out as a highly specialised lineage. Together, these findings suggest that colobine diets are shaped by interacting effects of phylogeny and geography, highlighting the role of evolutionary history and regional ecological context in structuring primate feeding strategies.