Figure 6. Plot showing a positive correlation (r2 = 0.84) between the average genome in each viral family versus the ratio (Cd/nCd) of codivergence (Cd) over non-codivergence (nCd) events.
The ratio is a measure of the linkage disequilibrium between the core polymerase gene and the remainder of the genome. Larger genomes tend to diverge in a more concerted fashion, whereas smaller genomes show greater independence in genetic segregation among constituents of their genomes. Hence smaller viral genomes behave somewhat like a mutualistic network, with the core acting as a host and the accessory satellites as symbionts.