Duplication and losses of opsin genes in lophotrochozoan evolution

Opsins are G-coupled receptors playing a key role in metazoan visual processes. While many studies enriched our understanding of opsin diversity in several animal clades, the opsin evolution in Lophotrochozoa, one of the major metazoan groups, remains poorly understood. We investigated the opsin evolution in 74 translated lophotrochozoan genomes and capitalized on recently developed phylogenetic approaches. We found that the common ancestor of Lophotrochozoa possessed at least seven opsin paralog groups that underwent divergent evolutionary history in the different phyla. Furthermore, we showed for the first time placopsin-related molecules in Bilateria, that we named pseudopsins, which may prove critical in uncovering opsin evolution.