Meeting Abstract
Evolutionary biology aims to understand the origins and adaptations of animal sensory systems because they play a vital role in organismal fitness. Visual systems in teleosts are suitable for the study of evolution because of their remarkable variation in visual sensitivities. This is due to the presence of several visual pigments, light-absorbing molecules based of a chromophore and an opsin protein. Opsin diversity is a product of the dynamic evolution involving gene duplication, gene loss, pseudogenization and gene conversion. Characiformes, with more than 2000 described species, is a diverse group of freshwater fishes inhabiting a wide range of ecosystems. Their Gondwanan origin, species richness and colorful patterns, make them an ideal group for studying visual systems and their adaptations. In this research, we disentangle the visual system of Neotropical Characiformes, through RNA-sequencing and physiological experiments. Our results show that species differ in opsin gene complements and that Characiformes exihibit opsin gene duplications in both long wavelength sensitive (LWS) opsins and rhodopsin (RH1) genes. Phylogenetic analyses suggest that the LWS and RH1 duplicates are paralogs, and the product of the teleost whole genome duplication presumably after their divergence with the spotted gar. Furthermore, through gene expression analysis and microspectrophotometry, we show that the duplicated LWS opsins have undergone neofunctionalization as they are differentially expressed in the retina and shift in spectral sensitivity to shorter wavelengths.
