RNA-based evolution is a theory that posits that RNA is not merely an intermediate between Watson and Crick model of the DNA molecule and proteins, but rather a far more dynamic and independent role-player in determining phenotype.
Since RNA processing is heritable, it is subject to natural selection suggested by Darwin and contributes to the evolution and diversity of most eukaryotic organisms.
In accordance with the central dogma of molecular biology, RNA passes information between the DNA of a genome and the proteins expressed within an organism.
[1] Therefore, from an evolutionary standpoint, a mutation within the DNA bases results in an alteration of the RNA transcripts, which in turn leads to a direct difference in phenotype.
[4][5] As life progressed and evolved over time only DNA, which is much more chemically stable than RNA, could support large genomes and eventually took over the role as the major carrier of genetic information.
The Tra gene, determinant of sex, in male flies becomes truncated as splicing events fail to remove a stop codon that controls the length of the RNA molecule.
In others the stop signal is retained within the final RNA molecule and a functional Tra protein is produced resulting in the female phenotype.
[11] During mammalian liver regeneration RNA molecules of growth factors increase in number due to the addition of signaling tails.
[13][14] By degrading transcripts, a lower amount of protein products are translated and the phenotype is altered by yet another RNA processing event.
[19] Human genome searches have also revealed RNA processing events that have provided significant “sequence space for more variability”.
RNA virus evolution appears to be facilitated by a high mutation rate caused by the lack of a proofreading mechanism during viral genome replication.
[23] In the Retroviridae ((+)ssRNA)(e.g. HIV), damage in the RNA genome appears to be avoided during reverse transcription by strand switching, a form of genetic recombination.