Species diversity and composition of dung beetle (Coleoptera: Scarabaeoidea) assemblages in North America

Data from 18 studies carried out on dung beetles from temperate North America (north of 25degree latitude) are compared to verify the existence of some geographical pattern in the variation of three parameters: (1) species number, (2) taxonomic composition, and (3) number of introduced species. Southern localities are characterized by a larger number of species and a significantly higher number of scarabaeine species than northern localities (only southern communities located inside the Chihuahuan desert do not conform to this pattern). To explain the latitudinal pattern in faunistic composition and number of species, historical factors are postulated. Foreign species of the tribe Aphodiini seem to be more frequent in the northern localities where more aphodiine native species occur. In contrast, foreign species of the subfamily Scarabaeinae are not more frequent in the southern localities with a greater number of native scarabaeine species. These results are consistent with the hypothesis that the more diverse assemblages of native dung beetle are more resistant to invasion by foreign species.