A PROBABILISTIC ANALYSIS OF A CLASS OF MALE RAT

SUMMARY The effect of sterilizing a given proportion of the male rat population on the birth rate of the population is analyzed using renewal theory. Two models are discussed. The first is applicable if each female rat during each estrous state selects her mates at random from the whole population. The second is applicable if each female rat determines a subgroup of the male population from which she selects her mates. For both models a high level of promiscuity reduces the effect of the sterilization, the first model being the more sensitive. This differing sensitivity suggests that one is more likely to observe chemosterility effects in the socially and environmentally structured rat population of the field study than in the rat population of laboratory study.