Minimum number of nucleotide differences in genes coding for cytochrome c in 20 different organisms

organism 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

1. human -- 1 13 17 16 13 12 12 17 16 18 18 19 20 31 33 36 63 56 66

2. monkey 12 16 15 12 11 13 16 15 17 17 18 21 32 32 35 62 57 65

3. dog 10 8 4 6 7 12 12 14 14 13 30 29 24 28 64 61 66

4. horse 1 5 11 11 16 16 16 17 16 32 27 24 33 64 60 68

5. donkey 4 10 12 15 15 15 16 15 31 26 25 32 64 59 67

6. pig 6 7 13 13 13 14 13 30 25 26 31 64 59 67

7. rabbit 7 10 8 11 11 11 25 26 23 29 62 59 67

8. kangaroo 14 14 15 13 14 30 27 26 31 66 58 68

9. duck 3 3 3 7 24 26 25 29 61 62 66

10. pigeon 4 4 8 24 27 26 30 59 62 66

11. chicken 2 8 28 26 26 31 61 62 66

12. penguin 8 28 27 28 30 62 61 65

13. turtle 30 27 30 33 65 64 67

14. rattlesnake 38 40 41 61 61 69

15. tuna 34 41 72 66 69

16. screwworm 16 58 63 65

17. moth 59 60 61

18. Neurospora (mold) 57 61

19. Saccharomyces (yeast) 41

20. Candida (yeast) --

Source: Walter M. Fitch, Science, vol. 155, Jan. 20, 1967, p. 281, © 1967 by the AAAS.