The visual system of Characiformes: a window to the teleosts lineage Daniel Escobar-Camacho1*, Karen L. Carleton1, Nevika Narain2, Michele E.R. Pierotti3 1Department of Biology, University of Maryland, College Park, MD 20742, USA. 2Environmental Sciences, Anton de Kom University of Suriname, Paramaribo, Suriname. 3Naos Laboratories, Smithsonian Tropical Research Institute, Panama, Republic of Panama. *[email protected]

Evolutionary biology aims to understand the origins and adaptations of animal sensory systems because they play a vital role in organismal fitness. Visual systems in teleosts are suitable for the study of evolution because of their remarkable variation in visual sensitivities. This is due to the presence of several visual pigments, light-absorbing molecules based of a chromophore and an opsin protein. Opsin diversity is a product of the dynamic evolution involving gene duplication, gene loss, pseudogenization and gene conversion.

Characiformes, with more than 2000 described species, is a diverse group of freshwater fishes inhabiting a wide range of ecosystems. Their Gondwanan origin, species richness and colorful patterns, make them an ideal group for studying visual systems and their adaptations.

In this research, we disentangle the visual system evolution of Neotropical Characiformes through RNA-sequencing and physiological experiments. We analyzed the transcriptomes of 13 Geotria_australis_LWS species that belong to different families within the order Gallus_gallus_LWS LWS Anolis_carolinensis_LWS_ and we performed microspectrophotometry in six wild- Homo_sapeins_NM Homo_sapiens_NM Xenopus_laevis_LWS caught species. Callorhinchus_milii_LWS_1 Callorhinchus_milii_LWS_2 _Lepisosteus_oculatus_LWS Scleropages_formosus_LWS_2 Our results show that species vary in opsin gene Characiformes LWS-2 Scleorpages_formosus_LWS_1 Carassius_auratus_LWS complement due to gene duplication and gene loss, and Danio_rerio_LWS1 Danio_rerio_LWS2 that this has occurred repeatedly and independently L11867_C_auratus_LWS_translation Characiformes LWS-1 among different Characiform lineages. Further, Clupea_harengus_LWS Teleost-specific genome duplication Salmo_salar_LWS Characiformes have lost the uv opsin and exhibit Oncorhyncus_mykiss_AF425073_LWS Oreochromis_niloticus_LWS Gasterosteus_aculeatus_LWS duplications in both long wavelength sensitive (LWS) Oryzias_latipes_LWS Poecilia_reticulata_LWS_1 and rhodopsin (RH1) opsin genes. Phylogenetic analyses P_reticulata_LWS_2 P_reticulata_LWS_3 suggest the LWS and RH1 duplicates are product of the 0.08 teleost whole genome duplication that occurred Geotria_australis_RHA RH1 Anolis_carolinensis_RH1 presumably after the divergence with the spotted gar. Gallus_gallus_RH1 Latimeria_chalumane_RH1 Callorhincus_milii_RH1 Lepisosteus_oculatus_RH1 Furthermore, through gene expression analysis and Scleropages_formosus_RH1

Danio_rerio_RH1_2_ microspectrophotometry, we show that the duplicated Epalzeorinchos_bicolor_RH1_2 LWS opsins have undergone neofunctionalization. The Carassius_auratus_RH1_2 Characiformes RH1-2 LWS duplicates are differentially expressed in the retina Danio_rerio_RH1_1 Epalzeorinchos_bicolor_RH1_1 and this opsin expression profile varies between species. Teleost-specific Carassius_auratus_RH1_1 genome duplication Characiformes RH1-1 Finally, the LWS duplicates exhibit a shift in spectral Clupea_harengus_RH1_1

Salmos_salar_RH1 sensitivity (~30nm) to shorter wavelengths due to amino Gasterosteus_aculeatus_RH1 acid substitutions in known spectral tuning sites in the Oreochromis_niloticus_RH1 Poecilia_reticulata_RH1 opsin sequence. Oryzias_latipes_RH1

0.09 Figure 1. Phylogenetic relationships among teleosts of the opsin classes LWS and RH1