Costly Solicitation, Timing of Offspring Conflict, and Resource Allocation in Plants

The theory of parent–offspring conflict is extended to plants that produce many offspring in one reproductive event. The energetic cost of begging signals and the timing of offspring conflict are explicitly taken into account. We find that if the indirect costs of increased provisioning of selfish offspring are borne by their brood mates, then offspring are selected to solicit in so costly a way that a substantial part of parental investment in a brood goes to solicitation rather than offspring's growth and survival. Consequently, offspring conflict often results in smaller seed size than the parental optimum in the absence of conflict, although each offspring still consumes more resources than the amount its mother is willing to give. While the optimal sex allocation can be shown to be independent of solicitation and sibling conflict, the overall reproductive effort is always lowered by parent–offspring conflict. The timing of offspring conflict during the period of parental investment is demonstrated to be an important factor that influences the outcome of parent–offspring conflict. The more resources are allocated to individual offspring before the occurrence of offspring solicitation, the less offspring should solicit, and hence the closer the offspring size to the parental optimum. Copyright 2000 Annals of Botany Company