The relationship between body size and population abundance in summer dung beetle communities of south-European mountains (Coleoptera: Scarabaeoidea)

The relationship between body size and population abundance was studied in summer dung beetle communities of three South-European mountains: southern Alps (France), eastern Pyrenees (France), Sierra de Gredos (Spain). Middle-sized species dominated in southern Alps and in the Sierra de Gredos, but the large-bodied species (Geotrupinae) presented the highest population densities in the Pyrenean communities. The domination of large-bodied species in the Pyrenees was linked with a noteworthy low diversity (under-representation of Aphodiinae and Coprinae). Our results showed (i) that the relationship between body size and population density does not present a homogeneous pattern in South-European dung beetle communities. So, the study of local assemblages does not allow to infer underlying evolutionary trends. (ii) Conversely this analysis allows to assume that interspecific competition played a main role in the formation of the Pyrenean fauna. Three hypotheses are proposed to explain the specificity of Pyrenean communities.