Functional evolution and molecular dynamics of light-sensitive opsin receptor adaptations

The ability to capture incoming wavelengths of light and perceive the colours of the world stems from peripheral light-sensitive G-protein coupled opsin receptors in the eye, ultimately informing visually guided behaviours. Here we explore the molecular and functional basis of visual adaptations in lepidopteran and odonate insect groups with multifaceted visual ecologies. By leveraging a cell-based opsin expression platform, we start mapping Gq opsin genotype-phenotype relationships, pinpointing spectral residues and revealing molecular mechanisms underlying shifts in insect ultraviolet (UV), short-wavelength (SW), and long-wavelength (LW) light sensitivity. We also investigate the interplay between regulatory phototransduction networks, gene expression plasticity, retinal mosaic and adaptive opsin evolutionary trajectories. For instance, we find that in diurnal lycaenid and riodinid butterflies equipped with duplicate SW or LW opsins, coordinated functional opsin shifts and specialized opsin mosaic patterns contribute to fine discrimination of intraspecific long-wavelength coloration. Opsin tuning in trichromatic hawkmoth pollinators follows lineage-specific diel adaptations for enhanced short or long-wavelength light capture, whereas LW opsin expression plasticity contributes to colour-tuning potentially aiding mate-search recognition behaviours in damselflies. By merging advances in molecular genetics research on peripheral visual receptors, our results contribute to disentangling the functional and regulatory basis of evolutionary adaptations underlying insect sensory visual phenotypes.