Figure 9.13 The effect of different sex ratios on a mother’s fitness. When one son can breed with multiple daughters in an isolated population, the sex ratio of the mother’s offspring will affect the number of grandoffspring that can be produced. In this example, we assume each female can produce six offspring. (a) If a mother produces three daughters and three sons, 18 grandoffspring can be produced. (b) If a mother produces five daughters and one son, 30 grandoffspring can be produced.