Table 20-5: Synonymous and Nonsynonymous Polymorphisms and Species Differences for    Alcohol Dehydrogenase in Three Species of Drosophila

Organism

Species differences

Polymorphisms

Nonsynonymous

7

2

Synonymous

17

42

Ratio

0.29:0.71

0.05:0.95

Source: J. McDonald and M. Kreitman, “Adaptive Protein Evolution at the Adh locus in Drosophila,” Nature 351, 1991, 652–654.