Repeated evolution: Retroviral gene co-opted 177 times independently in vertebrates

It is not easy to believe, that a virus inserts its DNA into a vertebrate species genome, and later on, this DNA chunk will aid species reproduction. And this should have happened many times independently in various species … It would be a miracle if this would work once, let alone many times … This is really not easy to believe, because species’ reproduction seems to be is a pretty important thing, should work flawlessly, because if not – no reproduction – no evolution …

Endogenous retroviruses are ubiquitous in the vertebrate genomes. On occasion, hosts recruited retroviral genes to mediate their own biological functions, a process formally known as co-option or exaptation. Much remains unknown about the extent of retroviral gene co-option in vertebrates, although more than ten retroviral gene co-option events have been documented. Here, we use a phylogenomic approach to analyze more than 700 vertebrate genomes to uncover retroviral gene co-option taking place during the evolution of vertebrates. We identify a total of 177 independent retroviral gene co-option events in vertebrates, a majority of which have not been reported previously. Among these retroviral gene co-option events, 93 and 84 involve gag and env genes, respectively. More than 78.0% (138 out of 177) of retroviral gene co-option occurred within mammals. The gag and env co-option events share a generally similar temporal pattern with less frequent retroviral gene co-option identified in the deep branches, suggesting that retroviral gene co-option might have not been maintained for very long time periods. Moreover, we find co-opted retroviral genes are subject to different selection pressure, implying potentially diverse cellular functionality. Our study provides a comprehensive picture of co-opted retroviral genes during the evolution of vertebrates and has implications in understanding the ancient evolution of vertebrate–retrovirus interaction.


Frequent Retroviral Gene Co-option during the Evolution of Vertebrates | Molecular Biology and Evolution | Oxford Academic (