Fig. 2

Overlapping amount is strictly bounded. a A scatter plot showing the absolute number of overlapping nucleotides and genome lengths of all viral families. Only the X-axis is in log scale. Throughout the entire spectrum of genome length, viral genomes have a bounded amount of nucleotides involved in overlapping. Filtered out 3 outlying families (Nimaviridae, Phycodnaviridae and Iridoviridae with 85,155/305,110, 30,798/357,847 and 7956/144,698 overlapping/total nucleotides respectively), leaving 90 shown families. Spearman’s rank correlation is minimal (ρ = 0.26, p-value = 0.015). The dashed lines serve as thresholds (750, 1500 and 3000 nt) that demonstrate the bounded nature of the overlapping amount. Note that most viral families are below these bars. b Of the complete data set of 352 genera, most (273, 329 and 346) have a total number of overlapping nucleotides below the chosen thresholds (750, 1500 and 3000 nt), of which 85 genera (24 %) have no overlapping at all. Although the selection of thresholds is somewhat arbitrary, it can be seen that a saturation point is reached at around 1500 nt