Dung type or intraspecific variation in biomass: what is more important in determining dung beetle ecological function?

Abstract

We evaluated the relative importance of dung type and intraspecific variation in biomass on dung beetle function by quantifying the ecological functions (dung removal and soil excavation) of two dung beetle species under laboratory conditions: Dichotomius bos, which preferentially feeds on herbivorous dung, and Chalcocopris hesperus, which is a generalist coprophagous species. Two treatments were used, cattle dung and swine dung, which consisted of a container with soil, dung, and two individuals of the two species that had been weighed prior to the experiment. Dichotomius bos was better at dung removal and soil excavation in the treatment containing the dung of its preference, where as for C. hesperus, there was no difference between the treatments. Only the quantity of ecological functions performed by D. bos was positively related to biomass. For D. bos, dung type was more important than biomass in dung removal, and biomass was more important than dung type in the amount of soil excavated. Neither biomass nor dung type explained C. hesperus functions. In conclusion, variables that affect ecological functions are dependent upon the species in question and the type of function evaluated, so dung beetle ecological functions are species-specific.