The relative contributions of time and eggs to the cost of reproduction

Abstract

Whether the trade-off between current and future reproduction in insect parasitoids is mediated by the costs of time or eggs remains an issue of contention. Life-history models predict that parasitoids have some risk of exhausting their lifetime supply of oocytes. I develop a simple conceptual model that assesses the relative contributions of time and eggs to the cost of reproduction by placing them in a common currency: foregone future fitness returns. Although rates of egg limitation observed in nature are modest, eggs still often make the dominant contribution to the overall cost of oviposition. Therefore, models of parasitoid reproduction must recognize the costliness of both time and eggs.