Insights into dung beetle (Coleoptera: Scarabaeidae: Scarabaeinae) distribution along an elevational gradient in a tepui table-top mountain in the Brazilian Amazon

Abstract

Abstract Elevational gradients are excellent models to understand species distribution across sites with marked shifts in environmental conditions. In northern South America, tepuis are table-top mountains with elevations above 1000 m and high biodiversity and endemism levels. In this study, we assessed the effect of elevation on dung beetle (Coleoptera: Scarabaeidae: Scarabaeinae) assemblage structure (species richness, abundance, and biomass) in Tepequém, a tepui located in northern Brazil. Dung beetles were sampled with pitfall traps within seven elevational bands from 250 to 850 m. A total of 83 individuals from 14 species were collected, Oxysternon festivum (Linnaeus, 1758) and an unidentified Onthophagus species being the most abundant. Elevation did not affect beetle species richness and biomass. However, species composition from 750 to 850 m differed statistically from that recorded at lower elevations. Our results suggest that beetle assemblages possess a bimodal distribution along an altitudinal gradient on the Tepequém. The contrasting vegetation structure of tepuis between highlands (shrubland savannah vegetation) and lowlands (tropical rainforest) explains the different composition of the assemblages. This study should be considered as a starting point in improving our understanding of the dung beetle diversity of tepuis, which present a unique singular relationship between elevation and species diversity.