Influence of variations in threshold of bad mutations on age structure of the population

Computer study of population evolution in a modified Penna model is presented, where different thresholds T for bad mutation may be assigned to individuals. The model indicates a possible source of such fluctuations of T due to embryo period of life before birth. Changes in age characteristics of the population, survival rate and mutation distributions at equilibrium are discussed. Results of computer simulation are compared with the standard Penna model with no fluctuation in T. We obtained larger equilibrium population for the same environmental capacity. However, the survival rate is smaller and the age of the oldest individuals also decreases. This is also reflected in age distribution of the population, similar at older populations and with higher decrease rate among younger ones. Also, the mutation accumulation is similar for older ages, yet younger individuals may absorb more mutations as a result of the presence of some items with threshold value above the average T. We conclude that fluctuations in threshold T may alter population characteristics, also in terms of measurable statistics in population such as age distribution or the survival rate.