Aggregation of Larval Diptera Over Discrete and Ephemeral Breeding Sites: The Implications for Coexistence

Abstract

Theory suggests that coexistence is enhanced among competing insects breeding in discrete and ephemeral resources, if the larvae are aggregated over the breeding sites. Field data on fruit-breeding diptera show that they have a negative binomial distribution over fruit items and are highly aggregated. An analysis of the processes that could lead to a negative binomial suggests that variation in breeding site quality or in the fecundity of female flies is unlikely to be the cause of such aggregation. As long as each site receives rather few visits from flies, the observed distributions could be caused by females laying their eggs in clutches, that is, laying several eggs at a time. Most insects breeding in discrete and ephemeral resources are likely to have aggregated distributions, so we would expect large numbers of species to be able to coexist in such sites.