Fig. 1

A scheme of the model simulations. a Stages of an individual simulated lifespan. b At each timepoint during the simulation the modeled population undergoes 5 main updates: 1. Individuals that have not reached maturity increase their body mass following their growth curve, starting from the initial birth mass and up until they reach their inherited body mass (parent body mass with variation proportional to parent mutation rate); mature individuals remain at the same body mass. 2. Each individual past maturation reproduces with a certain inherited frequency of reproduction, producing on average an inherited number of progeny per litter, each progeny’s birth body mass is inherited from its parent with variation proportional to the parent’s mutation rate. Each individual is tried in a binomial trial with a small probability (at each timepoint) of dying of three main causes: 3. Death following limitations imposed by ecosystem carrying capacity which allows for a certain maximum population size and promotes intra-specific and inter-specific competition for resources if population numbers exceed this capacity. 4. Death caused by predation is modelled based on the Lotka-Volterra model of predator-prey interaction [34]. 5. Death caused by physiological aging, such as due to cancer, frailty or other age-related causes; the probability is negligible early in life but increases exponentially with age; the speed of increase of the probability of death caused by aging depends on an individual’s aging profile which is determined by the aging curve as explained in Fig. 3a, “Theoretical introduction to the modeling” subsection of Results and “The somatic maintenance program paradigm” subsection of Methods