|  | Substitutions at the 3rd codon position | Substitutions at the 1st and 2nd codon positions | ||||
---|---|---|---|---|---|---|---|
Outgroup | SpeciesA-Species B | Ma | Mb | χ2 | Na | Nb | χ2 |
N. vit | P. pil- P. sp. | 13 | 7 | 1.80 | 3 | 4 | 0.14 |
A. mel | A. bak- P. pil | 52 | 44 | 0.67 | 9 | 8 | 0.06 |
 | A. bak- P. sp. | 53 | 45 | 0.65 | 9 | 10 | 0.05 |
D. mel | C. c- A. bak | 73 | 72 | 0.01 | 19 | 17 | 0.01 |
 | C. c- P. pil | 78 | 56 | 3.61 | 16 | 17 | 0.03 |
 | C. c- P. sp. | 79 | 56 | 3.92* | 18 | 16 | 0.12 |
 | C. sm- C. c | 58 | 34 | 6.26* | 20 | 12 | 2.00 |
 | C. sm- A. bak | 85 | 60 | 4.31* | 22 | 12 | 2.94 |
 | C. sm- P. pil | 94 | 48 | 14.90*** | 22 | 15 | 1.32 |
 | C. sm- P. sp. | 99 | 52 | 14.63*** | 24 | 14 | 2.63 |