IBDSim: a computer program to simulate genotypic data under isolation by distance.

IBDSim is a package for the simulation of genotypic data under isolation by distance. It is based on a backward 'generation by generation' coalescent algorithm allowing the consideration of various isolation by distance models with discrete subpopulations as well as continuous populations. Many dispersal distributions can be considered as well as heterogeneities in space and time of the demographic parameters. Typical applications of our program include (i) the study of the effect of various sampling, mutational and demographic factors on the pattern of genetic variation; and (ii) the production of test data sets to assess the influence of these factors on inferential methods available to analyse genotypic data.