Coalescence time for two genes from a subdivided population

In this paper a new form of the solution for the Laplace transform and mome nts of the distribution of the waiting time for two genes to coalescence is presented. The two genes are sampled from a subdivided population where mi gration rates between populations are constant in time. Equal subpopulation size is not assumed. For the special case of an island model with equal mi gration rates between islands, the Laplace transform of the coalescence tim e and the first and second moments are found explicitly. The new form of th e solutions allows numerical calculation. The connection of how the results relate to a panmictic population when migration rates are large is illustr ated using strong-migration-limit theory.