Hello! I ran codeml branch-site test (null and alternate) on 2118 genes and found that 42 of these are significant and thus, contain sites under positive selection. Now I need to find these sites using the Bayes Empirical Bayes (BEB) method. I read the paper already but I don't understand which tool to use to find these sites under selection. Does anyone know how to identify specific sites under positive selection using the PAML branch-site model output? Thanks!
2 answers
Sites under selection are listed after the analysis for that given model. As an example, this is in the codeml output for one of my analyses after testing model M8:
Bayes Empirical Bayes (BEB) analysis (Yang, Wong & Nielsen 2005. Mol. Biol. Evol. 22:1107-1118)
Positively selected sites (*: P>95%; **: P>99%)
(amino acids refer to 1st sequence: S03amoenu)
Pr(w>1) post mean +- SE for w
2043 N 0.759 1.245 +- 0.469
2119 L 0.559 1.007 +- 0.579
2221 T 0.588 1.043 +- 0.569
2310 N 0.744 1.229 +- 0.480
2321 I 0.633 1.099 +- 0.549
2606 P 0.655 1.125 +- 0.538
3434 V 0.865 1.373 +- 0.330
3451 N 0.756 1.242 +- 0.472
3454 I 0.717 1.198 +- 0.498
3518 I 0.631 1.096 +- 0.550
3575 T 0.607 1.067 +- 0.561
Given that model M8 is selected as the best-fit model, the BEB analysis suggests that those sites (codons) are under positive selection.
Hi Brice! Thanks so much! I was just about to reply to my own question because I learned this info right after putting up the post this morning. Thanks for your reply!
Taruna
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