Fig. 1

Alignments of amino acid sequences of MHC class I exon 2 in non-passerine (a) and passerine (b) birds. Dots indicate amino acids identical with the reference consensus sequence. Residues under pervasive positive selection (FUBAR/FEL) are marked with dark red, residues under episodic positive selection (MEME) and marked with light red, while residues under negative selection (FUBAR/FEL) are marked with blue. Variation in selection parameter (dN–dS; FUBAR analysis) is shown above the alignments