The frequency of recessive lethal heterozygotes among inidividuals obtained from inbred strains. A random-number simulation study.

In small and moderate sized inbred strains the variation with regard to the frequency of lethal heterozygotes is of such a magnitude that it is almost impossible to predict the degree of heterogeneity from one generation to another. This was shown from computer simulations of the generational variation in inbred strains maintained by full-sib matings at different breeding regimes. The results are discussed in relation to Haldane's theoretical derivations and to the practical implications with regard to strain keeping and to design and evaluation of experiments.