Figure 1. Distribution of positive-sense single-stranded RNA virus genome sizes.

The Coronaviridae is split into the corona- and toro-/bafinivirus groups. Prefix Nido- and Picorna- are for Nidovirales and Picornavirales, respectively. Group specific box-whisker plots are aligned along the X-axis by their medians (bold line) normalized to zero. The box spans from the first to third quartile; the whiskers (dashed lines) are <1.5 times the inter-quartile range; outliers are circles. Families/groups are ranked by median genome size along Y-axis. Genome size ranges are colored by semi-circles: nidoviruses (dark orange), other classified (dark grey) and unclassified viruses (light grey). Three non-overlapping zones regarding the presence of the exoribonuclease (ExoN) are highlighted in the genome size distribution (from top to bottom): ExoN-encoding large nidoviruses and NDiV (light green); in-between not-sampled size zone (white); ExoN-lacking ssRNA+ viruses (light blue).