Frozen Evolution. Or, that’s not the way it is, Mr. Darwin. A Farewell to Selfish Gene.

Organisms with a large genome contain pairs of a great many genes or frequently have very numerous groups of genes that were formed at some time in the past through duplication of the original sequence and began to fulfill various functions following mutual differentiation.These genes are frequently, although not entirely accurately (see XXIV.9.1), called paralogous genes, abbreviated as paralogs.The presence of these mutually quite similar sequences at various sites in the genome entails the risk of illegitimate recombination, i.e. recombination between sequentially identical or similar DNA sections located at various loci.In the vast majority of cases, illegitimate recombination reduces the viability of cells and any progeny they may have.

            One of the ways in which evolution could reduce the risk of illegitimate recombination consists in mutual differentiation of these genes by insertion of introns at various positions or otherwise identical or quite similar nucleotide sequences (Duret 2001).As a consequence, the primary structures of the two genes will differ substantially at the level of the DNA, while they can remain similar and even identical at the level of the spliced mRNA (Fig. XI.9).Similarly as in the case of the error-detection model, this means of using introns is theoretically possible, but empirical data confirming its actual role are currently lacking.