Drivers of ant composition, richness, and trophic guilds in Neotropical iron ore cavities

Abstract

Subterranean habitats may be considered limiting for animal colonization, especially for ants, due to permanent darkness and mainly because of oligotrophic conditions. While not as deep as limestone caves, iron ore caves and other subterranean habitats may be more available for colonization because of their shallower depth. We use the richness and composition of ants to assess how differences in habitat structure affect the biodiversity and ecosystem function between cavities and surrounding epigean landscapes. We predicted that the distribution of ants would be different because of the variation in habitat structure and cavity conditions may act as a filter for colonization by ants. A high diversity of ants was found in the 20 sampled cavities (26 species), and most of them were grouped in the generalist trophic guilds. The distribution of ants occurred independently of the type of cavity to which they are associated (caves, impacted caves and mines). Significant differences were observed in ant richness between epigean and cavities habitats, with lower average richness in cavities. The physical attributes of the cavities did not influence richness, mainly because cavity use by ants can usually be explained by their opportunistic habits and generalist lifestyle. Ants can participate directly in the cavities assemblage, playing roles in species composition and trophic functionality, due to the lower use restriction.