Genetic drift can play a role in the dynamics of all alleles in all populations, but it will play the biggest role for neutral alleles. A neutral polymorphism occurs when the segregating alleles at a ...Genetic drift can play a role in the dynamics of all alleles in all populations, but it will play the biggest role for neutral alleles. A neutral polymorphism occurs when the segregating alleles at a polymorphic site have no discernible differences in their effect on fitness. We’ll make clear what we mean by "discernible" later, but for the moment think of this as "no effect" on fitness.
