The Effect of Migration During the Divergence

The mean and variance of the number of nucleotide differences were obtained when the ancestral population diverged with migration. The number of nucleotide differences obtained indicates that not only the migration rate but also the period of migration has influence on a population structure. According to the migration rate and the period of migration, populations behave approximately as a single unit, diverged and isolated populations, two populations under equilibrium, or none of them. When Σm(t) is about one, the variance of the number of nucleotide differences becomes large, where Σm(t) is the sum of the migration rate for the period of migration. The distribution of the estimated divergence time was also obtained using computer simulations. It was found that the divergence time can be explained by Σm(t). That is, the divergence time is mostly estimated as the time when Σm(t) is less than 1.