Fig. 1.

Evolution of the narnavirus-like (+)RNA viruses. (A) Schematic dendrogram based on the phylogenetic tree for RNA-dependent RNA polymerases (RdRp) of Narna-Levi clade from Shi et al. (2016a). Major clusters of related viruses are shown as triangles colored in accord with virus host ranges: grey, bacteria; olive, fungi; blue, invertebrates; green, plants. Rough diagrams of typical virus genomes for each cluster showing encoded proteins (rectangles; homologous proteins are in the same color), their functions and the genome size in kilobases (Kb), are at the right. CP, capsid protein; MP, movement protein; S3H, superfamily 3 helicase. (B) Hypothetical scenario for the evolution of narnavirus-like viruses. Vertical arrows denote virus transmission that accompanies host evolution, whereas horizontal arrows show presumed horizontal virus transfer (HVT) between distinct host organisms.