Abstract
Heterogeneity in rates of survival, growth and reproduction among viruses is related to virus particle (i.e. virion) size, but we have little understanding of the factors that govern the four to five orders of magnitude in virus size variation. Here, we analyse variation in virion size in 67 double-stranded DNA viruses (i.e. dsDNA) that span all major biomes, and infect organisms ranging from single-celled prokaryotes to multicellular eukaryotes. We find that two metrics of virion size (i.e. virion volume and genome length) decrease by about 55-fold as the temperature of occurrence increases from 0 to 40°C. We also find that gene overlap increases exponentially with temperature, such that smaller viruses have proportionally greater gene overlap at higher temperatures. These results indicate dsDNA virus size increases with environmental temperature in much the same way as the cell or genome size of many host species.