Evolution of Opsin Genes in Caddisflies (Insecta: Trichoptera)

Abstract

AbstractInsects have evolved complex and diverse visual systems controlled by light-sensing protein molecules called opsins, which couple with a chromatophore to form photopigments. Insect photopigments group into three major gene families based on wavelength sensitivity: long wavelength (LW), short wavelength (SW), and ultraviolet wavelength (UV). Here, we identified 124 opsin copies from whole genome assemblies across 25 species of caddisfly (Insecta: Trichoptera). We discovered LW opsins to have most diversity across species and found that the LW opsins form two separate clades in the opsin gene tree. Conversely, we observed a loss of the SW opsin in half of the species of Trichoptera in this study, which might be associated with the fact that caddisflies are active during low-light conditions. Lastly, we found a single copy of the UV opsin in all of the species in this study, with one exception:Athripsodes cinereushas two copies of the UV opsin and resides within a clade of caddisflies with colorful wing patterns.SignificanceWhile opsins in some insect groups have been well-characterized, opsins have never been studied across caddisflies. Our findings provide insight into the diversity of opsins in caddisflies and form a basis for further research into the evolutionary drivers and complex visual systems in Trichoptera.