Structural traits projected onto the Pol dendrogram. The pol dendrograms in panels A to D are all derived from figure 1. A. The number of recognized Gag NC zinc finger motifs within respective genera. Detections of two NC zinc fingers are marked in light grey for all genera to the right from deltaretroviruses to betaretroviruses, and also for the gammaretroviral HERV-H. The remaining gammaretroviral elements (dark grey) had one NC zinc finger B. Presence of dUTPase is highlighted in grey. The non-primate lentiviral dUTPasePolA (dark grey) is found within Pol and the dUTPasePro (light grey) are found N-terminal of Pro. The dUTPasePro appears to occasionally have been lost, indicated by the two uncolored intermediate chicken and python ERVs. dUTPasePolB. of foamy viruses is not indicated. C. Nucleotide biases may be useful in demarcating retroviral groups locally and the most obvious found are here highlighted. For more detail see refs [31, 40]. D. Genera with detected Pol C-terminal GPY/F motifs are marked light grey and Pro C-terminal G-patch marked in dark grey (exclusively in betaretroviruses). Some betaretroviruses missed a G-Patch and are therefore unmarked.