Table 4.
Directions of PCGs and rRNAs in the two clusters; tRNAs are not considered. Based on the lophotrochozoan ground pattern [34] we find two evolutionary lines. One is evident in Katharina, as well as in Octopus, with an inversion of PCGs in cluster 2. From this derived arrangement we can infer the Nautilus gene order with a “simple” translocation of rRNAs. The second line is an inversion of cluster 1 of the lophotrochozoan ground pattern, which leads to the monoplacophoran (and the Sypharochiton) pattern of gene arrangement. We could not detect this arrangement of PCGs in another lophotrochozoan group so far (see e.g., [80])
| Cluster 1: cox3-nad3-nad2-cox1-cox2-atp8-atp6 |
Cluster 2: rrnS-rrnL-nad1-nad6-cob-nad4L-nad4-nad5 |
Remarks | |
|---|---|---|---|
| Lophotrochozoan ground pattern (Bernt et al. [34]) | → | → | |
| Monoplacophoran plesiomorphic state | ← | → | Cluster 1 missing atp8 in L. hyalina as it was not sampled |
| L. antarctica | ← | → | |
| Vema ewingi | ← | → | |
| L. hyalina | ← | → | Cluster 1 misses atp8 |
| Sypharochiton spp. | ← | → | |
| K. tunicata | → | ← |