Effects of age- and state-dependent allocation on offspring size and number

Background: Empirical evidence from a range of taxa suggest age and condition can affect offspring size and number, but supporting theory is limited. Question: How do age and condition influence offspring size and number? Method: Dynamic state-dependent optimization. Key assumptions: We model a capital-breeding life history where an individual matures with all reserves available for reproduction. Results: We find that mortality risk and density-dependent offspring survival favour variation in allocation patterns. We predict that in species with sibling competition, females will reduce clutch size, but can compensate for fewer numbers of offspring with plasticity in offspring size and by reproducing several times over their life. In habitats with low mortality risk and some sibling competition, we predict an increased optimal offspring size in larger and older females.