The average number of generations needed to fix or lose an allele becomes significantly shorter as the allele frequency approaches either extreme, 1 or 0. When the population size is N, neutral mutation fixation time t is equal to 4N generations and a mutation with a selective advantage of s takes (2/s)ln(2N) generations to become fixed. For a mutant with a selective disadvantage, there is a low fixation probability, which means that if the mutant is to become fixed the fixation time must be much faster than neutral mutant. Selective advantage mutants behave similar to adverse mutations because the mutation is either quickly lost or quickly fixed. Additionally, the number of mutants fixed per generation is described by the rate of gene substitution. Numerically, the rate of substitution is equal to the total number of mutations multiplied by the probability of fixation. For a neutral mutation, the rate of substitution is independent of population size, however for alleles with genic selection the rate of substitution is population size dependent. The inverse of the rate of gene substitution is also equal to the average time between the fixation of two consecutive
The average number of generations needed to fix or lose an allele becomes significantly shorter as the allele frequency approaches either extreme, 1 or 0. When the population size is N, neutral mutation fixation time t is equal to 4N generations and a mutation with a selective advantage of s takes (2/s)ln(2N) generations to become fixed. For a mutant with a selective disadvantage, there is a low fixation probability, which means that if the mutant is to become fixed the fixation time must be much faster than neutral mutant. Selective advantage mutants behave similar to adverse mutations because the mutation is either quickly lost or quickly fixed. Additionally, the number of mutants fixed per generation is described by the rate of gene substitution. Numerically, the rate of substitution is equal to the total number of mutations multiplied by the probability of fixation. For a neutral mutation, the rate of substitution is independent of population size, however for alleles with genic selection the rate of substitution is population size dependent. The inverse of the rate of gene substitution is also equal to the average time between the fixation of two consecutive