Abstract
Populations are often divided into subpopulations. Biologists use the statistic F st to perform hypothesis tests for the existence of population subdivision and to estimate migration rates between different subpopulations. The distribution of F st is not known. In this article, we use coalescent theory methods to find the limiting distribution of F st in the large population, weak mutation limit under the island model of migration. Our analysis uses the scattering-collection decomposition of the island model coalescent introduced by Wakeley.