Genetic drift. Individual replications of the parameter sets highlighted in Figure 3. The migrant allele frequency of each replication at each generation are reported and plotted in line format, each replication is described by a single line. Only a sample of 50 replications was used, as 250 lines would be difficult to distinguish. The first parameter set is characterized by an initial allele frequency of 0.5 while the second parameter set has an initial migrant allele frequency of less than 0.001. Genetic drift and mutation cause the allele frequencies to change over time, resulting in some allele extinction and an overall distribution of frequencies at the end of the simulation.