Additional interactions involving two gene pairs

As we have seen in the previous examples, the abbreviated genotypic ratio 9AB : 3Ab : 3aB : lab gets variously modified, because two or more of these abbreviated genotypes give the same phenotype. We have thus found that 9:3:3:1 ratio gets modified into 9 : 3 : 4, 9 : 7 and 15:1 in three situations of epistasis, complementation, and duplication. One can think of several other possibilities giving ratios like 13 : 3, 12 : 3 : 1, 9:6: 1. Some of these examples are summarized in Table 3.6.