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 Ameri ca (north of 25 degrees latitude) are compared to verify the existence of s ome geographical pattern in the variation of three parameters: (1) species number, (2) taxonomic composition, and (3) number of introduced species. So uthern localities are characterized by a larger number of species and a sig nificantly higher number of scarabaeine species than northern localities (o nly southern communities located inside the Chihuahuan desert do not confor m to this pattern). To explain the latitudinal pattern in faunistic composi tion and number of species, historical factors are postulated. Foreign spec ies of the tribe Aphodiini seem to be more frequent in the northern localit ies where more aphodiine native species occur. In contrast, foreign species of the subfamily Scarabaeinae are not more frequent in the southern locali ties 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.