CLUTCH-SIZE BEHAVIOR AND COEXISTENCE IN EPHEMERAL-PATCH COMPETITION MODELS

Systems of patchy, ephemeral resources often support surprisingly dive rse assemblages of consumer insects. Aggregation of consumer individua ls over the landscape of patches has been suggested as one mechanism t hat can stabilize competition among consumer species. One mechanism fo r larval aggregation is the laying of eggs in clutches by females trav eling among patches to distribute their total fecundity. We use simula tion models to explore the consequences, for coexistence of competitor s, of larval aggregation that arises from clutch laying. Contrary to s ome previous treatments, we find that clutch laying can be strongly st abilizing and under certain conditions can be sufficient to allow comp etitors to coexist stably. We extend these models by considering clutc h size as a variable that responds to the abundance of resource patche s. Such a relationship might be expected because females should lay th eir eggs in fewer but larger clutches when the cost of travel among pa tches is high (because patches are rare). When females adjust clutch s ize in response to resource abundance, coexistence can be easiest when resource patches are scarce and most difficult when resources are abu ndant.