Endogenous retroviruses of non-avian/mammalian vertebrates illuminate diversity and deep history of retroviruses
Fig 5
Retroviral transmission modes at the land-water interface.
The blue boxes indicate aquatic environments. (A) Scenario where retroviruses underwent water-to-land transition simultaneously with the conquest of land by their tetrapod hosts. (B) Scenario where tetrapod retroviruses independently originated by cross-species transmissions from fishes to tetrapods after the origin of tetrapods.