Fig. 7

Models explaining how the copy number of genes with different functions is adjusted or selected. a In the regulated model, the duplicated minichromosomes distributed to the daughter cells are controlled within a range during amitosis. When cells encounter a stress environment, the copy number of environmental response genes is specifically adjusted to adapt to the new environment. b In the stochastic model, the duplicated minichromosomes are randomly distributed to the daughter cells during amitosis and the CNV pattern is shaped by natural selection. The housekeeping genes are more sensitive to dosage variation so only the progeny carrying correct dosages display high fitness and there is no selection for the dosage of environmental response genes under normal conditions. However, cells carrying certain copies of environmental response genes would be selected for in a stress environment