Figure 5. Fraction of duplicate genes for each gene class.

The figure showed that genes with more alternative promoters tend to have increased duplicability. The Y-axis is the fraction of genes belonging to duplicate gene in each gene class. SP means gene with single promoter while AP means gene with alternative promoters. AP = 2, AP = 3∼4, and AP> = 5 means gene with only 2 promoters, 3 or 4 promoters, and at least 5 promoters, respectively.