Assessment of spider assemblages and their responses to grazing regulation in the Great Indian Bustard habitat of Desert National Park, Rajasthan

Abstract

Arid ecosystems such as the Thar Desert are shaped by complex interactions between biotic and abiotic factors, with livestock grazing being one of the most influential drivers. Spiders, as dominant predatory arthropods, play a critical role in structuring invertebrate communities and serve as sensitive bioindicators. This study assessed spider assemblages and their responses to grazing regulation within the Great Indian Bustard habitat of Desert National Park, Rajasthan. Field surveys were conducted across enclosures and open-access areas for grazing using standardized sampling methods, which yielded a total of 16,775 individuals representing 29 families, 80 genera, and 114 species. Lycosidae, Salticidae, and Thomisidae were the dominant families, while grasslands harbored the highest diversity, and barren habitats supported the lowest. Analyses of alpha diversity revealed significantly higher species richness and evenness within grazing enclosures, highlighting the positive role of regulated grazing in maintaining vegetation structures conducive to spider assemblages. Beta diversity, on the other hand, indicated distinct community turnover between grazed and ungrazed sites, with several habitat specialists restricted to protected enclosures. Species accumulation and coverage-based rarefaction confirmed a robust sampling effort. Several noteworthy findings emerged from this work, including the description of multiple new species such as Stegodyphus thar, Latrodectus indicus, Afraflacilla miajlarensis, underscoring the underestimated diversity of arid-zone spiders. Overall, the study demonstrates that moderate regulation of grazing supports higher spider diversity and assemblage stability, thereby providing critical insights for biodiversity conservation in desert ecosystems and strengthening the role of spiders as ecological indicators for assessing habitat quality in the fragile Great Indian Bustard landscape.