Positive selection in the different lineages of genes of heme biosynthesis pathway.

a<p>Twice the difference between the log likelihood of M0 (one ratio) and two ratio model.</p>b<p><i>p</i>-value <i>p</i>(χ2) of the likelihood ratio test.</p>c<p>For the branch-site model A, the following four classes are demarcated to each amino acid: class 0 with 0< ω0<1 in all branches; class 1 with ω1 = 1 in all branches; class 2a with foreground ω2>1 but background 0< ω0<1; and class 2b with foreground ω2>1 but background ω1 = 1. p0 is the proportion of codons with 0< ω <1 in class 0; p1 is the proportion of codons with ω1 = 1 in class 1; p2a is the proportion of codons with foreground ω2>1 but with background ω0 in class 2a; p2b is the proportion of codons with foreground ω2>1 but with background ω1 = 1 in class 2b.</p>d<p>Bayes empirical Bayes (BEB) is used to calculate the posterior probabilities to identify the sites (amino acid residues) under positive selection (higher than 95%). The sites are indexed by the amino acids of the site in the human sequence (ALAS1, PBGS, UROD).