It's really just a proposal, there would have to be some associated enzyme that targets genes at the well-known splice site (maybe something like a CRISPR-relat

It's really just a proposal, there would have to be some associated enzyme that targets genes at the well-known splice site (maybe something like a CRISPR-related Cas etc. enzyme?)and inserts the intron sequence. This seems to date from this 2012 study: > "Birth of new spliceosomal introns in fungi by multiplication of introner-like elements (2012)" https://pubmed.ncbi.nlm.nih.gov/22658596/ https://pubmed.ncbi.nlm.nih.gov/22658596/ These are postulated to be relatively rare events, so catching one in the act would be difficult: > "However, dating of multiplication events showed that they degenerate in sequence and length within 100,000 years to eventually become indistinguishable from RSIs. We suggest that ILEs not only account for intron gains in six fungi but also in ancestral eukaryotes to give rise to most RSIs by a yet unknown multiplication mechanism." [ILE's being closely related intron sequences, RSIs being the regular jumbled-up types]