Meeting Abstract

94.1  Friday, Jan. 7  Timetree of vertebrate visual opsin genes suggests long cryptic history of metazoans SANTINI, F.; Univ. of California, Los Angeles santini@ucla.edu

Vertebrate visual opsins are light-sensitive G protein-coupled receptors found in photoreceptor cells of the retina. Vertebrate visual opsin belong by five different groups: RH1, which is used in night vision and is found in rod photoreceptor cells; RH2, LWS/MWS, SWS1 and SWS2, employed in color vision, and found in the cone photoreceptor cells. Very little is currently known about the tempo of opsin evolution. While it is likely that the most recent common ancestor of vertebrates possessed both rod and cone opsins, it is not clear how old the gene duplication events that lead to the current diversity of vertebrate visual opsins are. I will present a timetree of 120 visual opsin genes that includes all five visual opsin types found in all major vertebrate groups and that was dated with 28 vertebrate fossils. The analysis indicates that the divergence of visual opsins started over 800 mya, long before the oldest fossil record of vertebrate animals, possibly indicating that metazoans are much older than currently assumed. The gene duplication events that generated the current diversity of vertebrate visual opsins occurred over a long time span (over 200 my), while some vertebrate lineages (e.g., spiny-rayed fishes) experienced rapid bursts of repeated gene duplication events. Possible links between gene duplication events and significant evolutionary events in the history of the major vertebrate clades will be discussed.