Lagman, D.; Bergqvist, C. A.; Kuraku, S.

A crucial event in the evolution of compex vertebrate vision was the expansion of the visual opsin family in the ancestral vertebrate. However, it has been controversial whether the expansion was achieved through whole genome duplications or in tandem gene duplications. We here performed a vertebrate-wide genome comparison, including jawless vertebrates, which strongly favors the latter scenario. Our analyses uncovered frequent paralogy underlying homologous phenotypes caused by massive gene losses and distinct paralog utilization between jawless and jawed vertebrates.