Resource distribution unifies optimal offspring size and bacterial aging

Models of optimal offspring size and bacterial aging share the same underlying mathematical problem: how should a parent optimally distribute limited resources among its offspring? Optimal offspring size theory has long explored the trade-off between offspring number and size in higher organisms. Meanwhile, the emerging field of bacterial aging examines whether and under what conditions cells evolve unequal sharing of old cellular components. Despite addressing similar problems, these models remain constrained by field-specific assumptions. We unify them in a generalized resource-distribution framework that yields insights and predictions unreachable by either field alone. Our central finding is that the convexity of the function relating resources to offspring survivorship determines whether equal or unequal distribution of resources is the optimal strategy. We show that these optimal strategies evolve, characterize their robustness to fluctuating environments, and uncover the conditions that select for producing a "runt of the litter."