Epigean and hypogean drivers of Neotropical subterranean communities

Abstract

Aim: in addition to cave size and other subterranean habitat characteristics, cave entrances are important structurers of neotropical cave communities. However, little is known about the epigean ecosystems factors that might dictate the influence of entrances and the relationship among surface and cave communities, as entrance regions are ecotonal zones between the epigean and hypogean ecosystems. We aimed to assess the influence of epigean and hypogean factors as potential drivers of invertebrate species richness in Neotropical caves as well as the influence of the regional pool of invertebrate diversity on cave invertebrate diversity. Location: Limestone caves in south-eastern Brazil. Taxon: Invertebrates. Methods: data were collected in 48 caves within the Cerrado biome (Brazilian Savanna). The fauna sampling was performed by a direct intuitive search (DIS). Landscape characteristics and climatic parameters were accessed using geographic information systems. The characterization of the caves occurred during each sampling event. Regional diversity was based on the Taxonomic Catalog of Brazilian Fauna. To clarify the factors that significantly influence invertebrate species richness of the caves, we used generalized linear models (GLM). The relationship between regional diversity and cave diversity was evaluated based on linear models (LM). Results: overall, 1,173 species were found, of which 72 were obligate subterranean dwellers. The cave total species richness was influenced by hypogean factors and epigean factors. The species richness of obligate cave dwellers was significantly explained only by cave size. The regional pool of invertebrate species influenced the levels of biodiversity in the studied caves. The taxa with troglobitic species tended to be more diverse in caves than expected. Main conclusions: in addition to the influences of intrinsic cave variables, we highlight the importance of epigean factors on subterranean diversity in the Neotropics. The study shows the significant influence of the regional species pool on cave faunal composition. These findings reinforce the importance of considering the surrounding areas in actions regarding cave biodiversity conservation.