Poster Presentation Australian Society for Fish Biology Conference 2022

Seeing red in a blue world: unique body pigments require unique vision (#219)

Genevieve Phillips 1 , Ole Seehausen 2 , N. Justin Marshall 3 , Karen L Carleton 4 , Sara M Stieb 2
  1. Institute for Marine and Antarctic Studies, West Hobart, TAS, Australia
  2. Swiss Federal Institute of Aquatic Science and Technology, Swiss Federal Institute of Aquatic Science and Technology (EAWAG), Kastanienbaum, Switzerland
  3. Queensland Brain Institute, University of Queensland, St Lucia, Brisbane, QLD, Australia
  4. Department of Biology, University of Maryland, College Park, Maryland, USA

Labridae (Actinopterygii, Perciformes) are a polyphyletic family of over 500 species of fish in 60 genera of wrasses (labrids) and parrotfish (scarids), that includes iconic large fish such as the humpead parrotfish, Bulbometapon muricatum (1.3 m total length (TL)), and the pygmy possum wrasse, Wetmorella tanakai (0.04 m TL).  Labridae are very colourful fishes that are found in almost all marine environments. Their phylogeny is well-resolved, and they represent a diverse range of reproductive and behavioural ecologies, including variation in colour morphs at different developmental stages.  

Their evolutionary biology has generated considerable interest, and in previous work we uncovered high visual diversity, including multiple duplications of long wavelength sensitive (LWS) opsin genes. The evolution of diverse visual capabilites may explain why these families of fish are able to rapidly speciate. Specialising in longer wavelengths of light is particularly interesting in the coral reef environment where shorter wavelength sensitivities (SWS, RH2) tend to dominate. 

We assembled new data and re-analysed published data on labrid visual opsins to determine sequences and relative expression variability of opsin gene duplications. We then resolved duplication events across the labrid phylogeny using maximum likelihood (ML) trees with the known opsin sequence structure. Finally, we used estimates of LWS visual pigments spectral absorbance (based on sequence structure) to unravel whether LWS duplications may facilitate a functional mechanism for spectral tuning in the red. We have also modelled colour patterns within a labrid colour space to identify whether ‘labrid-specific’ colours are indeed ‘labrid-specific’. 

Here we show that both LWS and RH2A opsin duplications likely aid in seeing the unique ‘labrid-specific’ red and green colour patterns found within this group. Our results lend support to the theory that visual diversity is linked to specific functions within coral reef fishes.