Fig. 4. A classification of viral cheats.
A variety of different kinds of viral entities are cheats. We first divide viral cheats depending on whether the cooperation that is being exploited is intracellular or extracellular, then according to their origins, and finally, the specific gene products exploited, if known. We also denote the evolutionary timescales at which cheats exist. We divide between short-sighted cheats (in orange), which arise and spread within hosts, but not between hosts, and long-sighted cheats (in green), which spread both within and between hosts, and consequently persist over longer evolutionary timescales. We offer a few illustrative, but not exhaustive, examples of each type of cheat34,42,44,47,53,62,67–69,96,109,147–150.