Species | Fraction of rDNA units | Tandem* | Non-28S* |
|---|
D. simulans
| 0.08 | - | + |
D. sechellia
| 0.62 | + | + |
D. melanogaster
| 0.11 | -†| + |
D. yakuba
| 0.11 | - | + |
D. erecta
| 0.36 | + | - |
D. ananassae R1A | 0.17 | ++‡ | ++ |
D. ananassae R1B | 0.13 | +++ | +++ |
D. pseudoobscura
| 0.40 | +++ | +++ |
D. persimilis
| 0.26 | +++ | ++ |
D. willistoni
| 0.10 | + | ++ |
D. mojavensis
| 0.68 | + | + |
D. virilis
| 0.75 | ++ | + |
D. grimshawi
| 0.20 | + | + |
- *Plus signs indicate: +, less than 0.4 of those in 28S; ++, from 0.4 to 0.9 of those in 28S; +++, as many or more than those in the 28S; -, indicates absence. †Unlike the tandem R1s in the ancestral group, the sequence between the many tandem-like, consecutive R1 elements in D. melanogaster is typical of that found in an insertion site rearrangement (ISR) junction. Unlike the highly variable ISR junctions found in the locus, the ISRs between these tandem-like R1s are the same. Thus, these elements are likely the result of amplification of an original unique event. ‡All found upstream of R1B.
