Local and regional species ranges of a dung beetle assemblage from the semi-arid Karoo/Kalahari margins, South Africa

Distribution patterns were examined at both regional and local scales for an entire species assemblage of dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae) from the margins of the semi-arid Nama Karoo and the more mesic Kalahari sands in South Africa. At regional scale, we examined geographical species ranges of the entire assemblage recorded on the farm, Brulpan (28°56′S 21°48′E), near Groblershoop, Northern Cape. At local scale on Brulpan, we examined differences in species abundance, geographical and functional group composition between the assemblages occurring in three habitats (shrub karoo, isolated Kalahari dune, tree karoo) characteristic of the two major regional ecotypes. The dung beetle assemblage of 37 species and 12,505 individuals was mostly endemic to the south-west of southern Africa. The dune sand assemblage was numerically dominated by two groups of sand specialist species with geographical distributions centred in the south-west Kalahari although some species also occurred in sand outliers elsewhere in southern Africa. The assemblage comprised equal proportions of ball rollers, tunnelers and kleptocoprids (use dung buried by other dung beetles). The Karoo assemblages on stony sand were numerically dominated by a group of primarily soil generalist species centred in the south-westerly arid late summer rainfall region of southern Africa. Ball rollers dominated both karoo assemblages with the balance comprising primarily kleptocoprids. The distribution patterns indicate how differences in climate and habitat characteristics between the Karoo and Kalahari systems have strongly influenced both local occurrence of dung beetles and their regional ranges and range edges in southern Africa.