Figure 1.

Phenotypic assortment due to the amitotic divisions of the macronucleus. Schematic representation of phenotypic assortment in the Mac genomes of Tetrahymena during asexual reproduction. The larger circle represents the macronucleus and small gray circle indicates the micronucleus, which is not shown in the dividing cells. For simplicity the Mac genetic content is represented by only three copies of one autonomous replicating piece (ARP) initially with two different alleles (straight double lines and dotted lines). As the process of phenotypic assortment occurs the frequency of heterozygous cells in the population gradually decreases until a completely homozygous population is form.