Mutation Accumulation

In sexual populations, strong selection maintains high survival before maturity and high reproductive potential near maturity. In the constant adult mutation-rate case, mutation accumulation produces no finite equilibrium in the full non-linear model. Increased late-life variance argues against aging being an adaptive program in this model. Mutation-accumulation theory holds that late-acting deleterious alleles are removed weakly by selection because fewer future births depend on survival to late ages. Classical evolutionary theories predict that early-acting deleterious mutations are efficiently removed while late-acting harmful mutations can accumulate. Offspring inherit parental genetic traits and receive new irreversible harmful mutations during reproduction. Harmful mutations expressed before reproduction face selection, while those expressed only after reproduction can accumulate. The model treats deleterious mutations as point-mass increments to the continuous-age hazard function. The no-equilibrium result is interpreted as unraveling caused by backward propagation of Walls of Death through adult ages. The equilibrium condition balances mutation-rate density against the exp…