Molecular fossils illuminate the evolution of retroviruses following a macroevolutionary transition from land to water

• DOI: 10.1371/journal.ppat.1009730
• Publication Date: 2021-07-12T17:42:11Z
• Authors: Jialu Zheng; Jianhua Wang; Zhen Gong; Guan-Zhu Han
• Keywords: Endogenous retrovirus

The ancestor of cetaceans underwent a macroevolutionary transition from land to water early in the Eocene Period >50 million years ago. However, little is known about how diverse retroviruses evolved during this shift terrestrial aquatic environments. Did into accompanying their hosts? infect through cross-species transmission after invaded environments? Endogenous (ERVs) provide important molecular fossils for tracing evolution transition. Here, we use phylogenomic approach study origin and ERVs cetaceans. We identify total 8,724 within genomes 25 cetaceans, phylogenetic analyses suggest these cluster 315 independent lineages, each which represents one or more endogenization events. find that cetacean originated two possible routes. 298 ERV lineages may derive retrovirus occurred before most were reaching evolutionary dead-ends. 17 are likely arise events split mysticetes odontocetes, indicating infected non-cetacean mammals life Both integration time synteny support recent ongoing activity multiple retroviral some proliferated hundreds copies host genomes. Although only recorded proportion past infections, our findings illuminate complex marked transitions vertebrate history.