Evolution of sensory systems: Using opsin genes to see through the eyes of fish
Cichlid fishes are some of the most diverse fishes on earth. They inhabit both clear and murky lakes from Africa to South America. Cichlid visual sensitivities are highly variable, and result from a combination of seven possible cone opsin proteins with a light sensitive chromophore. Variation in sensitivities is the result of changes in opsin sequence, opsin expression, and opsin co-expression, which differ between developmental stages as well as between species. We have isolated several causative mutations that alter opsin expression differences using next generation sequencing and retinal transcriptomes. These mutations act additively to alter gene expression. In addition, we have found that the light environment can alter cichlid visual sensitivities with rapid (<3 day) changes in gene expression. I’ll discuss how these different mechanisms have evolved and their implications for cichlid diversity.