Genetic Drift of neutral alleles
( f(B) = 0.5, N = 50, W0 = W1 = W2 )
In the absence of natural
selection in a finite population, the frequency f(B)
of an allele is subject only to random genetic drift.
Replicate populations with N = 50 drift from
an identical initial f(B) = 0.5 to fixation and loss, with equal expectation,
respectively, in <200 generations. The brown population f(B)
drifts to < 0.1 before drifting to fixation, while the blue population twice drifts
> 0.5 prior to loss. The trajectories are random: careful
inspection would show that the count of positive
and negative changes of f(B) over time are equal,
whereas the magnitude of dq in
either follows the normal distribution.
Text material © 2025 by Steven M. Carr