Figure 1. Three typical configurations of the model with i_b >i_d and their effect on progeny’s genotypes as a function of parental age.

(upper panel) Each haploid individual is defined by a parameter x_b defining its fertility span of intensity i_b and a parameter x_d defining the time during which it will maintain itself, with an intensity i_d. These parameters can be positive or null. (a) ’Too young to die’: it corresponds to configurations satisfying x_d <x_b. (b) ’Now useless’: it corresponds to configurations where x_b = x_d. (c) ‘Menopause’: it corresponds to configurations where x_d >x_b. (lower panel) Each individual may randomly produce a progeny during its fertility span [0; x_b]. (d) In the case of physiologically young parents (a<x_d), the progeny’s genotype is that of its parent ∓ a Gaussian kernel of mutation centered on the parental gene. In the case of the reproduction event occurring after x_d, for configuration (a) above, two cases are observed, (e) if the organism carries a Lansing effect ability, the x_d of its progeny will be strongly decreased. (f) In the absence of the Lansing effect, the default rule applies.