RNA processing and the evolution of eukaryotes

In eukaryotes, RNA processing events, including alternative splicing and RN A editing, can generate many different messages from a single gene. As a co nsequence, the RNA pool, which we refer to here as the 'ribotype', has a di fferent information content from the genotype and can vary as circumstances change. The outcome of a single RNA processing event often regulates the o utcome of another, giving rise to networks that affect the composition and expression of a particular ribotype. Successful ribotypes are determined by natural selection, and can be incorporated into the genome over time by re verse transcription. Eukaryotic evolution is therefore influenced by the al ternate ways in which RNAs are processed and the continual interplay betwee n RNA and DNA.