Figure 2
Evolutionary origin of cricket opsins. The phylogenetic tree is based on aligned, full-length amino acid sequences and was reconstructed using the Maximum likelihood method with honeybee pteropsin as an outgroup. No significant changes in tree topology were observed if other outgroups were used (Additional file 4). Numbers at the nodes indicate aLRT (approximate likelihood-ratio test) values for all nodes supported by more than 50%. G. bimaculatus sequences are highlighted in bold. The different insect opsin lineages are colored in violet (SW = short-wavelength clade), blue (MW = middle-wavelength clade) and green (LW = long-wavelength clade). If known, the wavelength of peak sensitivity (λmax) of the respective visual pigment is given. The location of opsin expression is indicated by C for the compound eyes, and O and bold branches for the ocelli. M in brackets stands for the median eyes of Limulus, for which ambiguous results exist. For species names and references on sequences, expression data and λmax values see Additional file 2 and Additional file 3.