F-statistics of clonal diploids structured in numerous demes

The expected apportionment of genetic diversity in diploid clonal organisms structured in numerous subpopulations is explored. Under the specific assumptions considered, corresponding, for instance, to clonal pathogens infecting a large number of hosts, the co-ancestry between individuals within subpopulations is the only nontrivial quantity. Thus the population structure can be fully described either by F-ST or F-IS, as F-ST = -F-IS/(1 - F-IS). We show that, for most of the parameter space considered, including simulations where equilibrium is not reached and/or where homoplasy is high, the number of effective migrants is most accurately estimated as Nm = -(1 + F-IS)/4F(IS). We further propose a criterion to test for the absence of cryptic sexual reproduction based on the F-statistics F-IS and F-ST, which is applied to three previously published empirical data sets.