Meeting Abstract

94.2  Friday, Jan. 7  The role of gene duplication and convergence in the molecular evolution of scallop opsins KRAUSE, AJ; PAIRETT, AN; SERB, JM*; Iowa State Univ. serb@iastate.edu

Vision is a tractable system in which to study adaptation since the visual process is initiated by a single protein, opsin. Scallops possess tens to hundreds of image-forming eyes on the adult animal that contain both a rhabdomeric (Gq) and a ciliary (Go) opsin. Species are found in an array of photic environments and exhibit a diverse set of species-specific behaviors ranging from sessile attachers to extremely mobile long-distance swimmers. Previous work has shown that visual cues are used to orient swimming behaviors. Here, we report an unexpected degree of paralogous gene duplication in the scallop Gq-opsin. Interestingly, paralogous duplications appear to be functional and only occur within long-distance swimming lineages, which presumably rely more heavily on visual information. Furthermore, we identified similar functional motifs in the Gq-opsin copies from independent swimming lineages, which may indicate convergent evolution. We test whether amino acid modifications or whole gene duplications of Gq-opsin are correlated with either behavioral categories or photic environment using a comparative phylogenetic approach. To examine whether similar opsin sequences are the result of convergence, we use a multigene phylogeny of the scallops and the Gq-opsin gene phylogeny to identify the timing and number of the duplication events. Finally, we compare eye transcriptomes and genomic data for several scallop species to determine the degree of intraspecific duplication. Our results suggest that not only do eyes in long-distance swimmers have more genetic complexity (and possibly unrecognized structural complexity) than non-swimmers, but that long-distance swimming lineages have converged on a similar solution to obtain more visual information from the environment.