General codon-pair contexts.

In order to determine whether there are general rules for codon-pair contexts, the contexts that were negative or positive in the highest number of species were identified and sorted by the maximum and minimum residual value found for each context as shown above. As a consequence, contexts that have negative maximum values or positive minimum values have the same sign in all species of each domain (general rules). Codon-pair contexts that appeared more than once are underlined, while codon contexts of identical codons are shown in bold. Major preference for codon repetitions in eukaryotes is clearly visible in the dataset.