Table 1 Summary of the sequence changes observed for the different Sgs gene subfamilies in the 24 studied species. Numbers indicate the number of genetic events inferred for each Sgs gene
Sgs1 | Sgs3x | Sgs3e | Sgs3b | Sgs7-Sgs8 | |
|---|---|---|---|---|---|
inferred number of copies in the common ancestor of all studied species | 0 (appeared after the D. melanogaster/D. pseudoobscura divergence) | 1 | 1 | 1 | 0 (appeared after the D. melanogaster/D. pseudoobscura divergence) |
position and orientation relative to neighboring genes | constant | constant | constant | variable | variable |
first coding exon size | constant (28 bp) | constant (28 bp) | variable (19-28 bp) | variable (25-31 bp) | constant (28 bp) |
internal repeats | present | present | typically present | typically present | typically absent |
loss of all the internal repeats | 0 | 0 | 0 | 2 | not applicable |
gene deletion | 2 | 3 | 2 | 2 | 4 |
gene duplication | 0 | 0 | 0 | 4 | ≥ 3 |
gene inversion | 0 | 0 | 0 | 2 | ≥ 1 |
gene conversion | 0 | 0 | 0 | 2 | ≥ 3 |