Gene flow, Selection, & Drift

Bi-Directional Gene Flow between Two Populations

If two populations have unequal initial f(A) for the Red allele, and exchange individuals at unequal rates m and m', the expectation is that both populations will eventually achieve the same allele frequencies by mixing. However, if the A allele is subject to differential selection in the two populations (as in the uni-directional Island Model), and (or) drift results in random variation in f(A) greater than m and m', a uniform f(A) will not be reached. The interplay of gene flow, selection, and drift results in population structure of genetic variation within species.