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

Elizabeth H Raine,Eleanor M Slade

doi:10.1098/rspb.2018.2002

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.

Highlights

Indicator species are often used as a more efficient way to assess ecosystem integrity than sampling a large number of taxa [1]
Studies of dung beetle–mammal associations accounted for 65 papers, 68 papers focused on dung beetle– ecosystem functioning research and 226 studies consisted of empirical field studies of dung beetle– habitat associations
In each of the studies, we identified the effect a decline in mammal abundance or richness had on the dung beetle population

Summary

Introduction

Indicator species are often used as a more efficient way to assess ecosystem integrity than sampling a large number of taxa [1]. The effect of mammal species compositional change on dung beetles and their associated ecosystem functions has been little explored (but see [12,13,14]). While studies of dung beetles have provided a large body of information on species’ distributions and responses to land use change, they rarely shed light on the biotic interactions between dung beetles and mammals [12,13,14]. In contrast to dung beetles, mammals are notably harder to survey, requiring more time, effort and at a greater cost [47] Despite their close ecological association, and despite being two of the best studied vertebrate and invertebrate taxa individually, dung beetles and mammals are rarely studied in combination [48] (but see ‘Avenues for future work’ below for the potential of new molecular methods).

Material and methods

Results

Discussion

72. Galetti M et al 2017 Ecological and evolutionary

Findings

56. Bogoni JA et al 2016 Contributions of the mammal