NS 02-02

Genetic Drift among Populations over Time

The Wright-Fisher model for 10 simulated population, each with 2N = 100 and initial f(A) = f(a) = 0.5, over 100 generations. In any single population in any single generation, f(A) is equally likely to fluctuate "up" or "down." Note that one population has become "fixed" for allele A in Generation 83 [top line], and one is fixed for the alternative allele a (it has "lost" allele A) in Generation 100 [bottom line]. After 100 generations, four of the populations have f(A) > 0.5, and six have f(A) < 0.5: the mean f(A) remains constant at 0.5.

Figure ©2013 by Sinauer; Text material © 2018 by Steven M. Carr