The program “Nb_HetEx” estimates the effective number of breeders (N_b) that produced the sampled progeny based on genotype counts contained in that sample. When the number of breeders is very small, there is an excess of heterozygotes in their progeny: the smaller the number of breeders, the larger the heterozygote excess. The Nb_HetEx program also estimates N_e through the temporal method.

An investigation of the nature of dynamics of the population size and genetic structure is carried out for a homogeneous ecologically limited population influenced by density-dependent r-K selection in a single diallelic genetic locus. The detailed study of the results of basic types of natural selection is carried out with additional consideration of the influence of initial conditions. It is shown that coexistence of several different asymptotic dynamic modes (with their own attraction basins) is possible in numerous enough parametric domains which are meaningful biologically.