The spatial variability of rare and common species in a gall-inhabiting Lepidoptera community

Determining the spatial variability in abundance structure of rare species is necessary to assess the validity of the often claimed properties of rare species, i.e as being both vulnerable to extraction and good indicators of environmental change. The spatial concordance of the Lepidoptera species that inhabit a fungus-induced gall on Acacia karroo was examined across South Africa. A positive relationship wits found between species distribution and abundance. The common and moderately common species in the community were highly concordant, although the rare species were diffusive. As such, the vulnerability of the rare species in this community is difficult to assess and they are unlikely to make useful indicators of environmental change. Although preliminary results suggest that the community is temporally concordant, establishing the level of temporal, in addition to spatial, concordance of rarity is necessary to determine the mechanisms responsible for the abundance structure of rare species in communities.