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.

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.

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