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Experiments determining the process of mitochondrial DNA (mtDNA) transmission in eight female rabbits show that three processes, genetic drift in the germ line, short molecule selection and molecular diversity through high mutation rates, occur concurrently to mediate systematic heteroplasmy for long-repeat transmission. Heteroplasmy induces the onset of genetic drift while deletions and insertions of repeated subunits induce molecular diversity and elucidate the genetic drift. Mutation rates differ for each type, with the deletions in the one unit having a higher frequency than those in two units, indicating that the frequency profiles of mtDNA depend on the organ under study.

The mitochondrial genotype of all F(1) female offspring (426 individuals) of a single Drosophila mauritiana female, heteroplasmic for two types of mtDNA (a short and a long genome), was established. All descendants were heteroplasmic. The earliest eggs laid by this female show the cytoplasmic genetic structure of ovariole stem cells at the end of development. Cohorts of females from the eggs laid day after day by this female, throughout the 31 days of its life, provide information on the evolution of the mitochondrial genotypes in the course of successive divisions of stem cells. An increase of the percentage of long DNA in offspring was observed as the female aged. Moreover, the variance of the genotypes increases as rounds of stem cell division progress. These results are supported by observations based on the adults issued from the early and late eggs, for three additional heteroplasmic females.