Their allele frequencies at numerous genetic loci gradually become more and more different as new alleles independently arise by mutation in each population.
随着新等位基因在每个群体中独立突变产生，它们在许多遗传位点上的等位基因频率逐渐变得越来越不同。
2
Gene flow, the movement of alleles across the range of the species, is relatively free because individuals can move and then mate with individuals in their new location.