Fst and genetic drift in small populations

Key to genotype colors:

The frequency of allele A used at the start is p = 0.5 for all populations. Refresh your browser to start over. Scroll down for more details.

The following keys do something:

The status text shows:

The blue histogram at the top shows the distribution of p over the 12 populations (p = 0 at far left, p = 1 at far right).

With each new generation, drift increases the variance of p across populations and thus increases Fst (indicated by the fraction of the status bar filled with orange) until, eventually, all populations are fixed for either the A or the a allele, the variance of p is as large as it can get, and Fst equals 1.