Figure 1.

Neutral substitution rate as a function of (a) recruitment, (b) age at first reproduction and (c) age at last reproduction, when the other two variables are held constant. The figure is based on equation (2.3a), with constant population size (r = 0), K = U/T and U = 2.5 × 10⁻⁸ [20]. The direct causal effect of age at last reproduction on the substitution rate, as predicted by our model, is very small for most parameter combinations (panel (c), but see main text). Not all parameter combinations are possible (e.g. the constraints b < d and σf(d – b) > 1 must be fulfilled), which is why some curves are truncated. Displayed combinations illustrate the overall effect of LH-traits on K, but some sections of the curves may be unrealistic, even if possible in principle (e.g. early maturation combined with very low fecundity is unlikely in mammals).