Question

How does genetic drift result into evolutionary divergence? Could you explain with an example?

Answer 1

Because of genetic drift, the variance between demes (small subpopulations) increases over time (i.e., demes will diverge, esp. if they become isolated).
Given enough time, allele A or a will become fixed (p = 1 or p = 0).
The allele that is already more frequent will have a higher probability of being fixed:
The probability of a ("neutral") allele is its frequency (= 1/(2N) for a single gene copy).
Thus, the main features of genetic drift are:
a. A loss of genetic variation results within populations
b. Genetic divergence results between populations
c. Evolution results (i.e., allele frequencies change, until H = 0)