| Comments |
P.17878 left column 2nd paragraph: "A central question in evolutionary genomics is what mechanisms cause the variation observed in DNA base composition between and within genomes and how rapidly and by what mechanisms these biases might change in response to, for example, altered ecology and genetic constitution of the organism.
The large range in guanine plus cytosine (GC) content among bacterial species is well established, varying between at least 17% and 75% GC, with an even larger variation in the third
codon position (primary source). Within a genome, GC content usually is quite homogeneous and has a strong phylogenetic signal, but despite this overall homogeneity, there frequently exist strand-specific biases between the two strands of DNA such that the average nucleotide composition deviates from the theoretically expected A=T and G=C within each strand." |