BRISCOE, Adriana D.: Parallel Evolution of Red-Green Color Vision in Bees and Butterflies

A comparative approach was taken to identifying amino acid substitutions that may be under positive selection and are correlated with spectral shifts among orthologous and paralogous bee and butterfly long wavelength-sensitive (LW) opsins. Four novel LW opsin fragments were isolated, cloned and sequenced from eye-specific cDNAs from two butterflies, Vanessa cardui (Nymphalidae) and Precis coenia (Nymphalidae), and two moths, Spodoptera exigua (Noctuidae), and Galleria mellonella (Pyralidae). These opsins were sampled because they encode visual pigments having a naturally occurring range of lambda-max values (510-530 nm), which in combination with previously characterized lepidopteran opsins, provide a complete range of known spectral sensitivities (510 � 575 nm) among lepidopteran LW opsins. A maximum likelihood approach was used to reconstruct ancestral sequences from all available lepidopteran LW opsins with a high degree of certainty from these data. Reconstructed ancestral sequences revealed several instances of convergence to the same amino acid between butterfly and vertebrate cone pigments, and between independent branches of the butterfly opsin tree that are correlated with spectral shifts in visual pigment absorption spectrum. At least two of these sites were found to be changing in parallel among several independently-derived bee lineages.