Aggregation, habitat quality and coexistence: A case study on carrion fly communities in slug cadavers

Abstract

1. The aggregation model of coexistence for discrete patches of ephemeral resources was tested with Diptera communities in slug cadavers. 2. Slugs were exposed to the necrophagous fauna present at each of 32 birch woodlands. After 3 days the slugs were removed and emerging adult insects were retained and identified. 3. Density-specific aggregation (J), association between species (Cxy) and the necessary and sufficient condition for coexistence (Txy) were used to test the model. Woodlands were ranked on the basis of habitat quality that was defined by the diversity of species associated with each site. 4. Overall community and species-specific responses to resource mass were investigated. Results provided evidence for multispecies coexistence by interspecific aggregation, although there was also evidence of alternative mechanisms that promote coexistence. 5. Differences aggregation and interspecific association were found between high and low quality sites. The implications of these findings are discussed with particular reference to how differences in habitat quality affect aggregation and interspecific association.