Environmental and evolutionary factors collectively drive the geographic pattern in life-history trait diversity of terrestrial vertebrates across China

Life-history traits are characteristics that have evolved to optimize adaptation to external environments, and understanding their patters offer valuable insights for developing effective species conservation and restoration strategies. However, the biogeographical patterns of terrestrial vertebrates’ life history traits at macro scales, and the underlying mechanisms remain inadequately understood. Here, by assembling life-history trait and spatial distribution of 2334 species (398 amphibians, 211 reptiles, 541 mammals, and 1184 birds) in China, we estimated biogeographic patterns of trait diversity and identified their drivers. Our results indicate that South and Southwest China host assemblages with not only higher species richness and greater assemblage evolutionary distinctiveness, but also larger trait volume and high trait densities than expected under null models. These regions thus act as both evolutionary museums and cradles. Communities in the Tibetan Plateau exhibited a high trait volume but low trait density with a limited number of species, showing the prominent role of niche expansion. Our findings emphasize the importance of niche packing prior to reaching the current environmental saturation point in terrestrial vertebrates. Assemblages exhibiting greater assemblage evolutionary distinctive than expected show high trait volumes and low trait densities, underscoring an ecological linkage between phylogenetic history and trait diversity. Notably, amphibians exhibit a stronger environmental dependence compared to other three lineages, highlighting the need for focused conservation efforts. In conclusion, this study reveals the uneven patterns of trait diversity across China, driven by species richness, evolutionary distinctiveness, and environmental variation, providing valuable insights for guiding future conservation priorities for terrestrial vertebrates.