Contrasting patterns of alpine biodiversity across mountains and taxa worldwide.

The alpine biome, located at higher elevations of mountains worldwide, supports unique biodiversity and provides important ecosystem contributions to people. Despite the growing recognition of mountain biodiversity in international policy frameworks, substantial gaps remain in our understanding of how alpine biodiversity varies across mountain systems, undermining estimates of its conservation value and consequently effective conservation strategies. Here, we curate a dataset on alpine biodiversity, incorporating expert-validated data on species' elevational ranges for vascular plants, mammals, birds, and reptiles across 32 mountain ranges worldwide. We show that alpine biodiversity hotspots are concentrated in Neotropical regions, while most temperate regions represent coldspots with lower species richness. These patterns persist whether considering species with broad elevational ranges or only those strictly confined to the alpine zone. Unlike the classical latitudinal gradient of biodiversity, alpine richness patterns show no consistent relationship with latitude, highlighting the importance of regional history, landscape structure, and biogeographical processes.