Background: Slightly male-biased sex ratios occur commonly in animals with a higher male
juvenile mortality, including humans. RA Fisher's principle of equal sex ratios does not
explain these slightly biased sex ratios. Tainaka et al.(2006) suggested that male juvenile
mortality can cause a slight male bias. Aim: To develop and analyse a model of sex ratio and
extinction probabilities assuming sex-biased mortality. Hypothesis: Slightly male-biased sex
ratios reduce the probability of extinction of a population, leading to a shortage of one sex at …