Fig. 2.

Two “classical” examples of epigenetic phenomena in ciliates. Cortical inheritance: following asexual reproduction, the wild type singlet produces progeny that are also singlets (A) while mutant doublets produce doublet offspring (B). Non-Mendelian examples of mating type determination: in karyonidal inheritance, mating type varies either stochastically or is determined by changing environmental factors (e.g. temperature, time of day; C); in cytoplasmic inheritance mating types (O and E) are maternally inherited following conjugation (D; adapted from Chalker et al., 2013; Meyer and Garnier, 2002).