Human Pressures Drive Compositional Homogenization and Functional Shifts in Southeast Asian Mammal Communities

Human activities strongly alter wildlife distributions and behaviors, rapidly reshaping their community structure. Although links between human pressures and community assembly have been explored, practical integration of multiple biodiversity indicators, especially compositional homogenization and functional trait patterns, remains limited. We addressed this gap by jointly assessing the compositional and functional responses of mammal communities to human pressures across Southeast Asia. We compiled an extensive camera-trapping dataset from 4508 sites spanning > 38° of latitude across tropical and temperate forests in Southeast Asia. We quantified compositional homogenization and functional diversity trait patterns in relation to human pressures within and across forests. Our results show that community assembly is broadly affected by human pressures, with communities in Tropical & Subtropical Moist Broadleaf Forests (TSMBF) exhibiting greater vulnerability than those in Temperate Coniferous Forests (TCF), as evidenced by pronounced compositional homogenization and distinct changes in functional traits. High-intensity human modification promoted compositional homogenization alongside functional trait divergence, while long-term changes in building-density drove functional trait convergence. This study demonstrates that integrating compositional and functional indicators provides a more holistic understanding of anthropogenic impacts on biodiversity. The heightened vulnerability of tropical mammal communities underscores the urgent need for targeted conservation strategies in these regions to curb the replacement of endemic specialists with widespread generalists.