Figure 2.

The relative number of cumulative germline cell divisions in males and females. Until sexual maturity, the number of germline cell divisions in females (dotted red line) and males (solid blue line) is static. Then, female germ cells (eggs) experience only two divisions before reproduction while male germ cells (sperm) continue to divide throughout the remaining reproductive life of the male. Consequently the ratio of male-to-female germline cell divisions at reproduction, c, will increase as the age at reproduction of the male increases. Similarly, α, the male-to-female mutation rate ratio, is expected to increase as the average age of males at reproduction increases. The values of cumulative germline cell divisions here are modeled on human estimates, obtained from [10].