Dung beetle–mammal associations: methods, research trends and future directions

Abstract

Dung beetles are increasingly used as a study taxon—both as bioindicators of environmental change, and as a model system for exploring ecosystem functioning. The advantages of this focal taxon approach are many; dung beetles are abundant in a wide range of terrestrial ecosystems, speciose, straightforward to sample, respond to environmental gradients and can be easily manipulated to explore species-functioning relationships. However, there remain large gaps in our understanding of the relationship between dung beetles and the mammals they rely on for dung. Here we review the literature, showing that despite an increase in the study of dung beetles linked to ecosystem functioning and to habitat and land use change, there has been little research into their associations with mammals. We summarize the methods and findings from dung beetle–mammal association studies to date, revealing that although empirical field studies of dung beetles rarely include mammal data, those that do, indicate mammal species presence and composition has a large impact on dung beetle species richness and abundance. We then review the methods used to carry out diet preference and ecosystem functioning studies, finding that despite the assumption that dung beetles are generalist feeders, there are few quantitative studies that directly address this. Together this suggests that conclusions about the effects of habitat change on dung beetles are based on incomplete knowledge. We provide recommendations for future work to identify the importance of considering mammal data for dung beetle distributions, composition and their contributions to ecosystem functioning; a critical step if dung beetles are to be used as a reliable bioindicator taxon.

Co‐declining mammal–dung beetle faunas throughout the Atlantic Forest biome of South America

“…In doing so, this large-scale approach can depict the entire potential interaction network, because its metrics shows the status of the structure of consumer-detritivore food webs. In addition, it provide a key contribution to the understanding of dung beetle ecology, including: 1) a proxy of local interactions studies; 2) the co-occurrence patterns that can be compared with future studies based on experimental designs aiming to identify specific dung beetle resource use; 3) a basis for identifying drivers of dung beetle responses to ongoing mammalian declines; and 4) a way to provide an occurrence profile from the most common to the rarest species of both taxonomic groups across the Atlantic Forest (Raine and Slade 2019). Thus, we multiplied the dung beetle presence-absence matrix by the mammal presence-absence matrix for each radial cluster, to derive an incidence matrix between dung beetles and mammals.…”

“…At all scales, the networks revealed a high degree of connectance and nestedness, . Studies on the ecological interactions between dung beetles and mammals suggest that the structure of dung beetle feeding and breeding networks did not differ significantly and showed high degree of nestedness and low levels of trophic specialization (Raine et al 2018, Raine andSlade 2019). Acronyms in the figure are C: connectance; M: modularity; and N: nestedness.…”

“…Moreover, their eco-evolutionary traits (e.g. However, using dung beetles as bioindicators has been challenged due to a lack of understanding of the nature of their associations with different mammal taxa (Raine and Slade 2019). However, using dung beetles as bioindicators has been challenged due to a lack of understanding of the nature of their associations with different mammal taxa (Raine and Slade 2019).…”

Unexpectedly diverse forest dung beetle communities in degraded rain forest landscapes in Madagascar

“…This would inform us about the taxa these species use either as carrion or dung (Gillett, Johnson, Barr, & Hulcr, 2016;Gómez & Kolokotronis, 2017). In addition to unveiling the direct trophic interactions, identifying gut contents would enable describing how wide generalists or narrow specialists different species are, which remains largely unknown for dung beetles worldwide (Raine & Slade, 2019). Identification of species used by dung beetles would also allow using dung beetles as bioindicators to infer what other species occur in their environment (Carignan & Villard, 2002;Raine & Slade, 2019).…”

“…The evolutionary history of these groups has been established on a large scale, but the precise factors causing speciation need to be further studied (Miraldo & Duplouy, 2019;Wirta et al, 2008Wirta et al, , 2010. These factors include feeding patterns which play a strong role in dung beetle evolution (Davis, Scholtz, & Sole, 2016;Raine & Slade, 2019).…”