Sarkar2025_JWLS_Supplementary Material

The variation of species composition across ecological gradients is a key factor towards understanding and monitoring broad‐scale patterns and responses of biodiversity. Mountains provide unique opportunities to study assemblage variations (beta diversity) to changing habitats across short, yet contiguous distances. While this has been extensively studied across multiple taxa and regional scales, our understanding of Himalayan arthropod groups remains severely limited. Using spiders as a model taxon, this study investigates assemblage variations and their contributing microhabitat covariates. We assess how assemblages vary across different land-use types (forests: FR, agricultural lands: AG, and human-dominated regions: HD) along a common elevational gradient (1500-4500m) in a North-Western Himalayan landscape. While we found a general prominence of species turnovers in shaping spider communities, the study underscores stark differences in compositional structuring across differently managed land-use classes. Particularly notable is an unprecedented rate of absolute turnovers within FR communities, indicating high elevational sensitivities in otherwise widely distributed Palearctic species. AG and HD habitats accommodated specially adapted species with relatively higher nestedness, influenced by land management practices and synanthropy. The study also found the precedence of land-use affinities over natural elevational affinities in structuring spider assemblages, a phenomenon hitherto unknown across mixed-use landscapes of Indian Himalaya. We also found similar microhabitat covariates to have variable influences on assemblages across land-use types. This study provides novel insights into the interplay of elevation, land-use changes, and associated micro-habitats in shaping spider assemblages, offering valuable perspectives for effective conservation strategies amid compounded challenges of land-use shifts in Himalayan ecosystems.