# Evolution of Opsin Genes in Caddisflies (Insecta: Trichoptera)

## TL;DR

This study explores the evolution of light-sensing opsin genes in caddisflies, revealing diversity in long wavelength opsins and loss of short wavelength opsins in some species.

## Contribution

The study identifies new patterns in opsin gene evolution and diversity in caddisflies, including clade-specific losses and duplications.

## Key findings

- LW opsins show the most diversity and form two distinct clades.
- SW opsins are missing in half of the studied caddisfly species.
- UV opsins are typically single-copy, except in Athripsodes cinereus, which has two copies and colorful wings.

## Abstract

Insects have evolved complex and diverse visual systems in which light-sensing protein molecules called “opsins” couple with a chromophore 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). In this study, we identified 123 opsin sequences from whole-genome assemblies across 25 caddisfly species (Insecta: Trichoptera). We discovered the LW opsins have the most diversity across species and form two separate clades in the opsin gene tree. Conversely, we observed a loss of the SW opsin in half of the trichopteran species 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 the species in this study, with one exception: Athripsodes cinereus has two copies of the UV opsin and resides within a clade of caddisflies with colorful wing patterns.