Retrotransposons are mobile genetic elements that spread via the reverse transcription of RNA intermediates. They are abundant constituents of most fungal genomes and can lead to a wide range of genetic and genomic rearrangements.

Where did transposons come from?

Transposons were first discovered in corn (maize) during the 1940s and '50s by American scientist Barbara McClintock, whose work won her the Nobel Prize for Physiology or Medicine in 1983. Since McClintock's discovery, three basic types of transposons have been identified.

Did retrotransposons come from viruses?

Although it is formally possible that all retrotransposons are derivatives of infectious elements, it seems intuitive that on a global scale something more complex (a virus) originally evolved from something simpler (a retrotransposon).