Estimation of effective population size and migration rate from one- and two-locus identity measures

Standard methods for inferring demographic parameters from genetic data are based mainly on one-locus theor). However, the association of genes at dif ferent loci (e.g., two-locus identity disequilibrium) may also contain some information about demographic parameters of populations. In this article, we define one- and two-locus parameters of population structure as function s of one- and two-locus probabilities for the identity in state of genes. S ince these parameters are known functions of demographic parameters in an i nfinite island model, we develop moment-based estimators of effective popul ation size and immigration rate from one- and two-locus parameters. We eval uate this method through simulation, Although variance and bias may be quit e large, increasing the number of loci on which the estimates are derived i mproves the method. We simulate an infinite allele model and a K allele mod el of mutation. Bias and variance are smaller with increasing numbers of al leles per locus. This is, to our knowledge, the first attempt of a joint es timation of local effective population size and immigration rate.