Fig 3. The effect of the generation time on the sex-averaged yearly rate of replication-driven mutations.

The sex-averaged mutation rate per generation (solid purple line) increases with the generation time (assumed to be the same for males and females). Depending on the age of puberty (P), generation time (G), and the per cell division mutation rates, a linear fit to the number of mutations after puberty (dotted purple line) could have a zero, positive, or negative intercept at age zero, and the slope of this linear fit represents the yearly mutation rate after puberty. The slope of the green line represents the average yearly mutation rate prior to puberty. The effect of G on the overall average yearly mutation rate (m_R,y) depends on the relative values of the two slopes, which is equivalent to the sign of the intercept of dotted purple line at age zero: (A) If the intercept is zero, the dotted purple and green lines coincide, and the yearly mutation rates before and after puberty are equal, so the G does not affect m_R,y. (B) If the intercept is positive, the yearly mutation rate after puberty is smaller than that before puberty, so m_R,y decreases with generation time. (C) If the intercept is negative, the yearly mutation rate after puberty is greater than that before puberty, so m_R,y increases with generation time.