Reproductive allocation and reproductive ecology of seven species of Diptera

1. Variation in resource allocation to egg size and number was investigated in seven sympatric species of Piophilidae that oviposit on carcasses or di scarded cervid antlers: Liopiophila varipes (Meigen), Prochyliza xanthostom a Walker, Protopiophila latipes (Meigen), Protopiophila litigata Bondurians ky, Stearibia nigriceps (Meigen), and two unidentified species of Parapioph ila McAlpine. 2. Following optimal reproductive allocation theory, relatively larger, few er eggs were expected in (1) species that oviposit on antlers, where larvae probably experience lower risk of predation and greater competition than l arvae in carcasses, and (2) species with aggressive males and male-biased s ex ratios on the oviposition substrate, where risk of injury during oviposi tion may have favoured females laying fewer eggs. 3. Variation in reproductive allocation strategies could not be explained b y known differences in larval or adult environment, but congeneric species clustered by reproductive allocation patterns. The Parapiophila species pro duced larger, fewer eggs than the other species, and egg number increased s lowly with body size. The Protopiophila species did not deviate from expect ed egg sizes and numbers, and egg number increased steeply with body size. 4. An interspecific egg size-egg number trade-off resulted in a tight linea r scaling of ovary volume to body size, suggesting common physiological con straints on relative ovary mass. 5. Within each species, egg size was nearly constant whereas egg number inc reased with female body size, suggesting species-specific stabilising selec tion on egg size.