How reef fish see their colourful world: variability of visual pigment genes in damselfish (Pomacentridae) (#397)
The colour diversity and variable lifestyles of damselfish present a promising system to study the role of visual communication and adaptations in fishes. Making use of modern molecular approaches, like next generation sequencing, we show how light absorbing visual pigment genes (opsins – found within photoreceptors), respond to changes in visual needs on both phylogenetic and within lifetime timescales. Results so far reveal a conserved and yet flexible family of opsin genes in damselfish, to summarise:
- The visual system across damselfish species is surprisingly conserved
- The visual system within species is shaped by the light environment
- Anemone fish change their visual pigments with maturation
Damselfish possess five classes of opsins with one rhodopsin (RH1) used for scotopic vision, and four cone opsins used for photopic vision: short wavelength sensitive SWS1 and SWS2, medium wavelength sensitive RH2A and RH2B, and long wavelength sensitive LWS. By using Illumina sequencing combined with RT-qPCR we compared the profiles of cone opsin expression in more than 20 damselfish species and revealed that most species expressed the same three to four opsin types. This is surprising when considering that their diverse lifestyles are comparable to those found in African cichlids, a phylogenetically more restricted species assemblage showing a more diverse opsin palette. Within damselfish species, however, we found distinct quantitative variations. Populations inhabiting different depth light regimes regulate the expression level of their RH2 genes. More strikingly, in the anemone fish Amphiprion akindynos, immature to sexually matured individuals transferred from three to mainly one (SWS1) expressed opsin gene. Experiments now underway will examine if such patterns are widespread among other anemone fish species.
- Walter Salzburger & Justin Marshall have a shared senior authorship