The hierarchical island model revisited

Formulae were derived for the genetic differentiation between populations w ithin a metapopulation (F-SM), and between metapopulations (F-MT) as functi ons of migration and mutation rates, size and number of populations and met apopulations. We show that F-MT = 1/(1 + 4N(e)m), where N-e is the effectiv e size of a metapopulation, and where the migration rate between metapopula tions is m. The formulae for F-MT and F-SM were more general than previousl y proposed since we have relaxed some previously made hypotheses and we inc luded the effect of the mutation rate. Using our formula, some unexpected r esult of estimation of gene flow, previously obtained, can be explained rea dily.