The **Wright-Fisher model**
for **10 **populations, each with **N = 100** and
initial **q =**** f(****a****) = 0.5**, over
150 generations. In any single population in any single
generation, **f(a)** is equally likely to fluctuate "*up*"
or "*down*." By generation 150, two populations have
"*lost*" allele **a** (**q **** = 0**),
four have "*fixed*" it (**q = 1**), and of the
remaining polymorphic populations, two have **q****
> 0.5** and two have **q ****< 0.5**. The *global *mean
**f(****a****)** over all populations remains
constant at ~0.5, while variance increases over time.

Figure & Text material © 2021 by Steven M. Carr