A phylogenomic data-driven exploration of viral origins and evolution

Nasir, Arshan; Caetano-Anollés, Gustavo

The ABEV Venn group, which includes 442 FSFs encoded by both cells and viruses, was the most ancient group and covered the entire nd axis. The P-loop containing NTP hydrolase (c.37.1) FSF was the first FSF to appear at nd = 0. The median nd was~0.4, suggesting that at least 50% of ABEV FSFs originated very early in evolution and were shared by cells and viruses. This finding is remarkable and implies that some of the most ancient FSFs found in cells were also shared by very different groups of viruses, again suggesting the ancient coexistence of cells and viruses. In turn, the relatively longer tail on the right of the graph likely includes many FSFs of recent origin (nd > 0.63) that could have been gained in viruses from cells through HGT.