Simulated relationship between GC content and GCvsAT pressures derived from trinucleotide-motif preferences.

<p>The patterns were obtained from sequences generated by 64×4 substitution matrices derived from non-genic, coding, and intronic DNA alignments (solid, solid, and empty circles). The top plots show the pattern generated in absence of selection by the 64×4s derived from non-genic and coding-region DNA (left, right, solid circles), and by intronic 64×4s with and without strand effects (left, right, empty circles), the thick grey lines being the native non-genic and intronic human patterns (left, right). The middle and bottom plots show the patterns generated under Grantham non-synonymous selection, where grey lines are the mouse native patterns and smaller and larger empty circles label the results obtained from matrices with and without strand effects, respectively. The simulated data are otherwise the same as in the previous figure (see also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0002145#s2" target="_blank">Methods</a>).