AFRICAN FIG WASP COMMUNITIES - UNDERSATURATION AND LATITUDINAL GRADIENTS IN SPECIES RICHNESS

1. We examined species richness patterns for the wasps associated with southern and central African figs (Ficus) to determine if fig wasp communities are saturated with species and if the degree of saturation (or undersaturation) differs in temperate and tropical communities. 2. Saturation was tested by regressing local wasp-community richness (alpha diversity) against the regional wasp species richness (gamma diversity) of each fig species, and latitudinal variation in saturation was tested by regressing local community species richness against latitude. Separate analyses were conducted on the phytophagous, gall-forming wasps and their parasitoids. 3. We found no evidence that either galler or parasitoid communities are saturated with species. This conclusion was supported by high levels of variability in species richness found in individual trees and fruits and by generally low levels of resource utilization by gallers. 4. Local galler assemblage species richness was similar across a latitudinal gradient extending from 6-degrees-N to 34-degrees-S, suggesting that tropical and temperate communities are equally unsaturated. Local parasitoid community richness, on the other hand, dropped slightly towards the tropics, suggesting that tropical fig wasp parasitoid communities are even more unsaturated than temperate ones. 5. The lack of saturation in fig wasp communities is judged to be largely due to a combination of strong phylogenetic constraints on wasp species, some of which have probably co-speciated with their hosts (which limits regional species richness) and the ability of wasps to colonize ephemeral and unpredictable host resources (which limits local species richness). The patterns are those expected for communities of specialists.