Impacts of an indigenous settlement on the taxonomic and functional structure of dung beetle communities in the Venezuelan Amazon

Abstract

In the last 50 years, traditionally nomadic indigenous communities in Amazonia have increasingly adopted more sedentary lifestyles as a result of external influences. Permanent settlements lead to the concentration of disturbances (e.g., forest extraction and hunting) and threaten vulnerable species as well as those that provide important ecosystem services such as dung beetles. Here we evaluated the abundance, taxonomic, and functional structure (composition and diversity) of an ecological indicator group—dung beetles—along a disturbance gradient associated with a permanent settlement of the Joti people in the Amazonian region of Venezuela. We applied generalized linear model to assess the response of dung beetle abundance to settlement distance and latent variable model to assess the influence of settlement distance on taxonomic diversity and functional structure. We found the abundance of roller-species increased but small-bodied beetles decreased away from the settlement. We found that proximity to the Joti settlement did not affect metrics of taxonomic and functional diversity of the dung beetle assemblages in general, although functional evenness was lower away from the settlement. In contrast, we found impacts on the functional composition of dung beetles, with significant increase in the community-weighted means for roller species and large-bodied dung beetles away from Joti settlement. Our findings suggest that the transition from nomadism to a more sedentary lifestyle has not caused widespread collapse in the diversity of dung beetle assemblages surrounding the settlement, however significant trends were observed in species-specific responses to human impact, and these responses were mediated by functional traits.