Phylogenetic analysis of putative pigeon keratin proteins. Neighbour-joining minimum evolution trees of putative pigeon (A) alpha and (B) beta keratins showing the relationship to chicken keratins are presented. Putative pigeon keratins are given the prefix p followed by the ORF number, and chicken keratins are given the prefix c. For a list of GenBank IDs corresponding to the chicken keratins refer to Additional file 2. (A) Putative pigeon alpha keratins form two distinct groups. The first consists of type II cytokeratins (brown) and the second consists of type I cytokeratins (blue). (B) Putative pigeon beta keratins form several distinct groups including groups of feather (green), claw (purple) and scale (orange) keratins. Additionally there are several smaller groups that contain no chicken homolog.