Humans generally have polymorphisms where both alleles are found in both populations. The alleles may be either most prevalent or least prevalent in the population. Population has combinationof the polymorphic alleles. This is due to the fact that population is a breeding group and hence, transmit the genotypes which are broken down and new set/comobination of genotypes is generated in the progeny. Thus, the polymorphic alleles are also in continuum with an array of the frequencies of those alleles. Migration changes the freqency of the alleles since new polymorphisms or alleles are introduced into the population. If individuals are completely isolated, phenomena like founder effect occurs. Solution Humans generally have polymorphisms where both alleles are found in both populations. The alleles may be either most prevalent or least prevalent in the population. Population has combinationof the polymorphic alleles. This is due to the fact that population is a breeding group and hence, transmit the genotypes which are broken down and new set/comobination of genotypes is generated in the progeny. Thus, the polymorphic alleles are also in continuum with an array of the frequencies of those alleles. Migration changes the freqency of the alleles since new polymorphisms or alleles are introduced into the population. If individuals are completely isolated, phenomena like founder effect occurs..