Mutational patterns cannot explain genome composition: Are there any neutral sites in the genomes of bacteria?

Eduardo P C Rocha (1) , Edward J Feil (2)

1 Génomique évolutive des microbes
2 Department of Biology and Biochemistry

The dissection of natural selection and neutral processes remains a core problem for molecular evolutionary biologists. One of the longest-standing controversies con- cerns the causes of genome base compo- sition, notably the variation in the sum of G and C content (GC) between 17% and 75% in bacteria. Sueoka argued very early that GC content variation is driven by mutational biases and, as this bias affects non-synonymous sites, protein evolution might also be largely driven by neutral forces [1]. Later, Muto and Osawa showed that 4-fold degenerate positions in codons exhibit the largest range of GC content (GC4), whereas the non-degener- ate second codon positions (GC2) exhibit the narrowest (Figure 1) [2]. As the footprint of genomic GC variation is most evident in those sites under the least selective constraint for amino acid com- position, it has become accepted that GC content variation is primarily driven by neutral mutational effects and has little adaptive relevance [2].

Domaines: Bio-Informatique, Biologie Systémique [q-bio.QM]; Bio-informatique [q-bio.QM]

Eduardo P C Rocha, Edward J Feil. Mutational patterns cannot explain genome composition: Are there any neutral sites in the genomes of bacteria?. PLoS Genetics, 2010, 6 (9), pp.e1001104. ⟨10.1371/journal.pgen.1001104⟩. ⟨pasteur-00578536⟩