Evolution of Viruses

The study of virus evolution has historically been concerned with disease and its emergence and has not been integrated into the general study of evolution. Yet viruses dominate our planet and their evolution is a broad and applied field that can be studied in the real time (such HIV in human disease) and can also be applied to biotechnological problems. Virus evolution is very similar, but not identical, to host evolution. Darwinian principles apply, such as with Fisher population genetics, but other features, such as reticulated and quasispecies-based evolution, distinguish virus evolution. In RNA viruses, high error rates have led to the quasispecies concept in which collective populations are the basis of evolution. These populations provide viruses with high capacities for adaptation. Yet some RNA viruses show remarkable evolutionary stability. With DNA viruses, especially of bacteria, extensive recombination defines vast dynamic and ancient genetic pools. Temperate viruses can directly affect host gene pools by stable colonization. DNA viruses can be genetically complex and have evolved many unique viral genes. The retroviruses show both quasispecies-based rapid evolution and host-linked slow coevolution (e.g., endogenous retroviruses). Thus, virus evolution impacts all life and viral emergence continues to threaten human health.