Unveiling the microhabitat puzzle: how spatial heterogeneity shapes cave invertebrate biodiversity across scales

Caves harbor diverse invertebrate communities, but the processes shaping their diversity remain poorly understood in tropical systems. In this study, we tested the hypothesis that physical, trophic, and microclimatic factors drive patterns of species composition, richness, and phylogenetic structure in cave invertebrate communities. To address this, we conducted standardized active sampling of both microhabitat characteristics and invertebrate fauna across multiple spatial scales: cave-level, mesoscale (3 × 10 m), and microscale (1 × 1 m). We recorded a total of 357 invertebrate species, representing at least 55 orders, including 28 troglomorphic taxa. At the microscale, species composition was influenced by distance from the entrance as well as by spatial separation among caves, indicating that dispersal limitation, coupled with environmental constraints such as oligotrophy in deeper zones, acts as an important structuring process. At the mesoscale, variation in shelter diversity and temperature was associated with species composition, suggesting that structural heterogeneity and microclimatic gradients function synergistically as environmental filters. Species richness at the microscale was positively related to both distance from the entrance and the availability of trophic resources, highlighting the role of resource input in promoting colonization, particularly in entrance zones. Phylogenetic distance was influenced by distance from the cave entrance and by trophic resource diversity. Collectively, these results provide mechanistic insights into the assembly of cave invertebrate communities and contribute to the development of conservation strategies tailored to karst ecosystems.