DOI: 10.5061/dryad.pg4f4qrp2
title: Human perturbations reduce dung beetle diversity and dung removal ecosystem function

description: Biodiversity drives ecological functioning, ultimately providing ecosystem
 services. Ecosystem processes are favored by greater functional diversity,
 particularly when groups of functionally different species interact
 synergistically. Many of such functions are performed by insects, among
 which dung beetles stand out for their important role in dung
 decomposition. However, anthropogenic disturbances are negatively
 affecting their ecological dynamics and ecosystem services. We conducted a
 manipulative field study, to evaluate the effect of human disturbance on
 dung beetle diversity (abundance, species richness, and functional group
 richness) and dung removal rates, comparing perturbed and conserved
 forests in three regions of Colombia (Caribbean, Andes, and Amazon). We
 also assess the relationship between dung beetle diversity and dung
 removal rates. Dung beetle diversity was assessed using pitfall traps, and
 specimens were measured and assigned to functional groups according to
 body size and dung relocation strategy. We used exclusion control units
 and experimental units to assess dung degradation with and without dung
 beetle activity and evaluate differences in removal rates between two dung
 removal strategies: paracoprids and telecoprids. Dung removal rates,
 abundance, and functional group richness were lower in perturbed forests
 compared to conserved forests. Dung removal increased with abundance,
 species richness, and functional group richness. Moreover, dung removal
 performed by telecoprids increased with species richness of telecoprids
 and paracoprids. Our results evidence a negative effect of human
 perturbation on dung beetle richness, abundance, and dung removal rates,
 and also that dung beetle diversity and functional group richness enhance
 dung removal rates.
description: Sampling design consisted of a 1,000 m linear transect per site,
 placed at the center of each forest
 (<i>i</i>.<i>e</i>., at least 100 m from the
 border of the forest to minimize any possible edge effect). Each transect
 included 20 baited pitfall traps (hereafter referred as ‘sampling units’;
 Figure S1B) placed 50 m from each other (Larsen & Forsyth, 2005;
 Figure S1B). The distance between our pitfall traps and experimental units
 is a potential caveat, taking into consideration that some dung beetle
 individuals could fly up to 1.5-2 km per day (Paik 1976). Each pitfall
 trap consisted of a 1 L plastic bucket buried at ground level and filled
 with 500 ml of water mixed with kitchen salt and scentless soap (following
 Noriega & Fagua, 2009). On top of the bucket, a metallic wire
 sustained a surgical mesh filled with 300 g of a mixture of fresh pig and
 human dung (homogenized and mixed in 4:1 proportion; Figure S1B). The
 amount of dung was chosen to be similar to that produced by large
 terrestrial mammals in Colombia, and we used the mixture because previous
 sampling campaigns showed that it is highly attractive to dung beetles in
 this region (J.A. Noriega pers. obs.). Traps were left in the field for 48
 hours. After this period, dung beetle specimens were collected and labeled
 in individual containers filled with ethanol (70%), to be later identified
 to species level using different taxonomic identification keys (Edmonds,
 1994; Génier, 1996; González<i> et al</i>., 2009; Camero,
 2010; Edmonds & Zidek, 2010; Vaz-de-Mello<i> et
 al</i>., 2011). Voucher specimens were deposited in the
 Entomological Collection of the Museum of Natural History of Los Andes
 University (EANDES) and the reference collection of the first author
 (CJAN).