A time series analysis of the population genetics of the self-incompatibility polymorphism. 2. Frequency-equivalent population and the number of alleles that can be maintained in a population

The concept of a frequency-equivalent population is introduced, which is the panmictic population that has the same allele frequency distribution as a given population with overlapping generations and variation in plant size. It differs from the traditional concept of effective population size, N(c), in that the effect of variation in plant size is to make the frequency-equivalent population larger than the actual population, whereas the effective population size is smaller. Overlapping generations has the opposite effect. The number of alleles that can be maintained in a population at equilibrium is calculated incorporating these two factors, with variation in plant size significantly reducing the number of alleles and overlapping generations increasing the number of alleles that can be maintained.