A phylogenetic reconstruction of SWS1 opsin evolution. A tree redrawn from Hackett et al. , showing shifts between violet (VS) and UV sensitivity (UVS) in SWS1 single-cone pigments (this study and references in text and S2). Taxa new to this study are shown in bold font. In parentheses are the codons and corresponding amino acid residues of the spectral tuning sites 86 (above line) and 90 (below). Nucleotide substitutions (lower case letters) are indicated at their most likely evolutionary position in the tree. The number of species that have been analysed per taxon is shown after taxon names (in bold folt for taxa sequenced in this study). For the sake of brevity, the Charadriiformes and Passeriformes clades have been collapsed. The evolution of SWS1 in these orders is reconstructed in  and [50, 51], respectively. Asterix (*) indicates that amino acid residue C86 has been found in a subset, family Accipitridae, of the order Accipitriformes.