LIMITED DISPERSAL, DELETERIOUS MUTATIONS AND THE EVOLUTION OF SEX

This study presents a mathematical model that allows for some offsprin g to be dispersed at random, while others stay close to their mothers. A single genetic locus is assumed to control fertility, and this locu s is subject to the occurrence of deleterious mutations. It is shown t hat, at equilibrium, the frequency of deleterious mutations in the pop ulation is inversely related to the rate of dispersal. This is because dispersal of offspring leads to enhanced competition among adults. Th e results also show that sexual reproduction can lead to a decrease in the equilibrium frequency of deleterious mutations. The reason for th is relationship is that sex involves the dispersal of genetic material , and thus, like the dispersal of offspring, sex enhances competition among adults. The model is described using the example of a hermaphrod itic plant population. Hort ever, the results should apply to animal p opulations as well.