Figure 2.

The effect of the fecundity schedule, m_x, on the likelihood that a death during age x is caused by cancer, c_x. We show the baseline beaver model (same line as the Type II in figure 1b) and four modifications where: (1) fecundity is halved for all age classes, (2) fecundity is doubled for all age classes, (3) fecundity has been front-loaded to earlier age classes while holding net reproductive rate, R₀, equal to the baseline and (4) fecundity has been back-loaded to later age classes while holding net reproductive rate equal to the baseline. Table 1 shows the effects of these scenarios on the optimal level of cancer suppression and the lifetime likelihood of dying from cancer. Early reproduction, while holding R₀ constant, results in the highest fraction of age-specific deaths occurring from cancer, followed by a halving of all values of m_x. Late reproduction, and doubling of the values of m_x results in the lowest values of c_x. Perhaps coincidentally, these last two scenarios resulted in the same curves because they select for the same optimal level of cancer suppression.