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Hagen JFD, Roberts NS, Johnston RJ. The evolutionary history and spectral tuning of vertebrate visual opsins. Dev Biol 2023; 493:40-66. [PMID: 36370769 PMCID: PMC9729497 DOI: 10.1016/j.ydbio.2022.10.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 10/27/2022] [Accepted: 10/31/2022] [Indexed: 11/11/2022]
Abstract
Many animals depend on the sense of vision for survival. In eumetazoans, vision requires specialized, light-sensitive cells called photoreceptors. Light reaches the photoreceptors and triggers the excitation of light-detecting proteins called opsins. Here, we describe the story of visual opsin evolution from the ancestral bilaterian to the extant vertebrate lineages. We explain the mechanisms determining color vision of extant vertebrates, focusing on opsin gene losses, duplications, and the expression regulation of vertebrate opsins. We describe the sequence variation both within and between species that has tweaked the sensitivities of opsin proteins towards different wavelengths of light. We provide an extensive resource of wavelength sensitivities and mutations that have diverged light sensitivity in many vertebrate species and predict how these mutations were accumulated in each lineage based on parsimony. We suggest possible natural and sexual selection mechanisms underlying these spectral differences. Understanding how molecular changes allow for functional adaptation of animals to different environments is a major goal in the field, and therefore identifying mutations affecting vision and their relationship to photic selection pressures is imperative. The goal of this review is to provide a comprehensive overview of our current understanding of opsin evolution in vertebrates.
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Affiliation(s)
- Joanna F D Hagen
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD, 21218, USA
| | - Natalie S Roberts
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD, 21218, USA
| | - Robert J Johnston
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD, 21218, USA.
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2
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Hauzman E, Pierotti MER, Bhattacharyya N, Tashiro JH, Yovanovich CAM, Campos PF, Ventura DF, Chang BSW. Simultaneous expression of UV and violet SWS1 opsins expands the visual palette in a group of freshwater snakes. Mol Biol Evol 2021; 38:5225-5240. [PMID: 34562092 PMCID: PMC8662652 DOI: 10.1093/molbev/msab285] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Snakes are known to express a rod visual opsin and two cone opsins, only (SWS1, LWS), a reduced palette resulting from their supposedly fossorial origins. Dipsadid snakes in the genus Helicops are highly visual predators that successfully invaded freshwater habitats from ancestral terrestrial-only habitats. Here, we report the first case of multiple SWS1 visual pigments in a vertebrate, simultaneously expressed in different photoreceptors and conferring both UV and violet sensitivity to Helicops snakes. Molecular analysis and in vitro expression confirmed the presence of two functional SWS1 opsins, likely the result of recent gene duplication. Evolutionary analyses indicate that each sws1 variant has undergone different evolutionary paths with strong purifying selection acting on the UV-sensitive copy and dN/dS ∼1 on the violet-sensitive copy. Site-directed mutagenesis points to the functional role of a single amino acid substitution, Phe86Val, in the large spectral shift between UV and violet opsins. In addition, higher densities of photoreceptors and SWS1 cones in the ventral retina suggest improved acuity in the upper visual field possibly correlated with visually guided behaviors. The expanded visual opsin repertoire and specialized retinal architecture are likely to improve photon uptake in underwater and terrestrial environments, and provide the neural substrate for a gain in chromatic discrimination, potentially conferring unique color vision in the UV–violet range. Our findings highlight the innovative solutions undertaken by a highly specialized lineage to tackle the challenges imposed by the invasion of novel photic environments and the extraordinary diversity of evolutionary trajectories taken by visual opsin-based perception in vertebrates.
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Affiliation(s)
- Einat Hauzman
- Department of Experimental Psychology, Psychology Institute, University of São Paulo, São Paulo, Brazil.,Hospital Israelita Albert Einstein, São Paulo, Brazil
| | - Michele E R Pierotti
- Department of Zoology, Institute of Biosciences, University of São Paulo, São Paulo, Brazil
| | - Nihar Bhattacharyya
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Juliana H Tashiro
- Department of Experimental Psychology, Psychology Institute, University of São Paulo, São Paulo, Brazil
| | - Carola A M Yovanovich
- Department of Zoology, Institute of Biosciences, University of São Paulo, São Paulo, Brazil
| | - Pollyanna F Campos
- Laboratório de Toxinologia Aplicada, Center of Toxins, Immune-Response and Cell Signaling (CeTICS), Instituto Butantan, São Paulo, Brazil
| | - Dora F Ventura
- Department of Experimental Psychology, Psychology Institute, University of São Paulo, São Paulo, Brazil.,Hospital Israelita Albert Einstein, São Paulo, Brazil
| | - Belinda S W Chang
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON, Canada.,Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, ON, Canada
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3
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Seiko T, Kishida T, Toyama M, Hariyama T, Okitsu T, Wada A, Toda M, Satta Y, Terai Y. Visual adaptation of opsin genes to the aquatic environment in sea snakes. BMC Evol Biol 2020; 20:158. [PMID: 33243140 PMCID: PMC7690139 DOI: 10.1186/s12862-020-01725-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Accepted: 11/22/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Evolutionary transitions from terrestrial to aquatic life history cause drastic changes in sensory systems. Indeed, the drastic changes in vision have been reported in many aquatic amniotes, convergently. Recently, the opsin genes of the full-aquatic sea snakes have been reported. However, those of the amphibious sea snakes have not been examined in detail. RESULTS Here, we investigated opsin genes and visual pigments of sea snakes. We determined the sequences of SWS1, LWS, and RH1 genes from one terrestrial, three amphibious and four fully-aquatic elapids. Amino acid replacements at four and one spectra-tuning positions were found in LWS and RH1, respectively. We measured or predicted absorption of LWS and RH1 pigments with A1-derived retinal. During their evolution, blue shifts of LWS pigments have occurred stepwise in amphibious sea snakes and convergently in both amphibious and fully-aquatic species. CONCLUSIONS Blue shifted LWS pigments may have adapted to deep water or open water environments dominated by blue light. The evolution of opsins differs between marine mammals (cetaceans and pinnipeds) and sea snakes in two fundamental ways: (1) pseudogenization of opsins in marine mammals; and (2) large blue shifts of LWS pigments in sea snakes. It may be possible to explain these two differences at the level of photoreceptor cell composition given that cone and rod cells both exist in mammals whereas only cone cells exist in fully-aquatic sea snakes. We hypothesize that the differences in photoreceptor cell compositions may have differentially affected the evolution of opsins in divergent amniote lineages.
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Affiliation(s)
- Takashi Seiko
- Department of Evolutionary Studies of Biosystems, SOKENDAI (The Graduate University for Advanced Studies), Shonan Village, Hayama, Kanagawa 240-0193 Japan
| | - Takushi Kishida
- Wildlife Research Center, Kyoto University, 2-24 Tanaka Sekiden-cho, Sakyo, Kyoto 606-8203 Japan
| | - Mina Toyama
- Department of Biology, Faculty of Medicine, Hamamatsu University School of Medicine, Handayama, Hamamatsu Japan
| | - Takahiko Hariyama
- Department of Biology, Faculty of Medicine, Hamamatsu University School of Medicine, Handayama, Hamamatsu Japan
| | - Takashi Okitsu
- Laboratory of Organic Chemistry for Life Science, Kobe Pharmaceutical University, 4-19-1, Motoyamakita, Higashinada, Kobe, 658-8558 Japan
| | - Akimori Wada
- Laboratory of Organic Chemistry for Life Science, Kobe Pharmaceutical University, 4-19-1, Motoyamakita, Higashinada, Kobe, 658-8558 Japan
| | - Mamoru Toda
- Tropical Biosphere Research Center, University of the Ryukyus, Nishihara, Okinawa 903-0213 Japan
| | - Yoko Satta
- Department of Evolutionary Studies of Biosystems, SOKENDAI (The Graduate University for Advanced Studies), Shonan Village, Hayama, Kanagawa 240-0193 Japan
| | - Yohey Terai
- Department of Evolutionary Studies of Biosystems, SOKENDAI (The Graduate University for Advanced Studies), Shonan Village, Hayama, Kanagawa 240-0193 Japan
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4
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Hauzman E. Adaptations and evolutionary trajectories of the snake rod and cone photoreceptors. Semin Cell Dev Biol 2020; 106:86-93. [PMID: 32359892 DOI: 10.1016/j.semcdb.2020.04.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 04/09/2020] [Accepted: 04/09/2020] [Indexed: 10/24/2022]
Abstract
Most vertebrates have duplex retinas, with two classes of photoreceptors, rods and cones. In the group of Snakes, however, distinct patterns of retinal morphology are associated with transitions between diurnal-nocturnal habits and reflect important adaptations of their visual system. Pure-cone, pure-rod and duplex retinas were described in different species, and this variability led Gordon Walls (1934) to formulate the transmutation theory, which suggests that rods and cones are not fixed entities, but can assume transitional states. Three opsin genes are expressed in retinas of most snake species, lws, rh1, and sws1, and recent studies have shown that the rhodopsin gene, rh1, is expressed in pure-cone retinas of diurnal snakes. This expression raised many questions about the nature of transmutation and functional aspects of the rhodopsin in a cone-like photoreceptor. Extreme differences in the retinal architecture of diurnal and nocturnal snakes also highlight the complexity of adaptations of their visual structures, which might have contributed to the adaptive radiation of this group and will be discussed in this review.
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Affiliation(s)
- Einat Hauzman
- Department of Experimental Psychology, Psychology Institute, University of São Paulo, Av. Professor Mello Moraes, 1721, Bloco A - D9. Butantã, São Paulo, CEP. 05508-030, Brazil.
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5
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Da Silva MAO, Gade JT, Damsgaard C, Wang T, Heegaard S, Bertelsen MF. Morphology and evolution of the snake cornea. J Morphol 2019; 281:240-249. [PMID: 31876020 DOI: 10.1002/jmor.21094] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 12/06/2019] [Accepted: 12/15/2019] [Indexed: 11/11/2022]
Abstract
To investigate whether the thickness of the cornea in snakes correlates with overall anatomy, habitat or daily activity pattern, we measured corneal thickness using optical coherence tomography scanning in 44 species from 14 families (214 specimens) in the collection at the Natural History Museum (Denmark). Specifically, we analyzed whether the thickness of the cornea varies among species in absolute terms and relative to morphometrics, such as body length, spectacle diameter, and spectacle thickness. Furthermore, we examined whether corneal thickness reflects adaptation to different habitats and/or daily activity patterns. The snakes were defined as arboreal (n = 8), terrestrial (n = 22), fossorial (n = 7), and aquatic (n = 7); 14 species were classified as diurnal and 30 as nocturnal. We reveal that the interspecific variation in corneal thickness is largely explained by differences in body size, but find a tendency towards thicker corneas in diurnal (313 ± 227 μm) compared to nocturnal species (205 ± 169 μm). Furthermore, arboreal snakes had the thickest corneas and fossorial snakes the thinnest. Our study shows that body length, habitat, and daily activity pattern could explain the interspecific variation in corneal morphology among snakes. This study provides a quantitative analysis of the evolution of the corneal morphology in snakes, and it presents baseline values of corneal thickness of multiple snake species. We speculate that the cornea likely plays a role in snake vision, despite the fact that results from previous studies suggest that the cornea in snakes is not relevant for vision (Sivak, Vision Research, 1977, 17, 293-298).
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Affiliation(s)
| | - Jacob Thorup Gade
- Center for Zoo and Wild Animal Health, Copenhagen Zoo, Frederiksberg, Copenhagen, Denmark
| | - Christian Damsgaard
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Tobias Wang
- Zoophysiology Section, Department of Biosciences, Aarhus University, Aarhus C, Denmark
| | - Steffen Heegaard
- Eye Pathology Section, Department of Pathology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.,Department of Ophthalmology, Rigshospitalet, University of Copenhagen, Glostrup, Denmark
| | - Mads Frost Bertelsen
- Center for Zoo and Wild Animal Health, Copenhagen Zoo, Frederiksberg, Copenhagen, Denmark
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6
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Katti C, Stacey-Solis M, Coronel-Rojas NA, Davies WIL. The Diversity and Adaptive Evolution of Visual Photopigments in Reptiles. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00352] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
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7
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Schott RK, Van Nynatten A, Card DC, Castoe TA, S W Chang B. Shifts in Selective Pressures on Snake Phototransduction Genes Associated with Photoreceptor Transmutation and Dim-Light Ancestry. Mol Biol Evol 2019; 35:1376-1389. [PMID: 29800394 DOI: 10.1093/molbev/msy025] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The visual systems of snakes are heavily modified relative to other squamates, a condition often thought to reflect their fossorial origins. Further modifications are seen in caenophidian snakes, where evolutionary transitions between rod and cone photoreceptors, termed photoreceptor transmutations, have occurred in many lineages. Little previous work, however, has focused on the molecular evolutionary underpinnings of these morphological changes. To address this, we sequenced seven snake eye transcriptomes and utilized new whole-genome and targeted capture sequencing data. We used these data to analyze gene loss and shifts in selection pressures in phototransduction genes that may be associated with snake evolutionary origins and photoreceptor transmutation. We identified the surprising loss of rhodopsin kinase (GRK1), despite a low degree of gene loss overall and a lack of relaxed selection early during snake evolution. These results provide some of the first evolutionary genomic corroboration for a dim-light ancestor that lacks strong fossorial adaptations. Our results also indicate that snakes with photoreceptor transmutation experienced significantly different selection pressures from other reptiles. Significant positive selection was found primarily in cone-specific genes, but not rod-specific genes, contrary to our expectations. These results reveal potential molecular adaptations associated with photoreceptor transmutation and also highlight unappreciated functional differences between rod- and cone-specific phototransduction proteins. This intriguing example of snake visual system evolution illustrates how the underlying molecular components of a complex system can be reshaped in response to changing selection pressures.
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Affiliation(s)
- Ryan K Schott
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
| | | | - Daren C Card
- Department of Biology, University of Texas, Arlington, TX
| | - Todd A Castoe
- Department of Biology, University of Texas, Arlington, TX
| | - Belinda S W Chang
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada.,Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
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Gower DJ, Sampaio FL, Peichl L, Wagner HJ, Loew ER, Mclamb W, Douglas RH, Orlov N, Grace MS, Hart NS, Hunt DM, Partridge JC, Simões BF. Evolution of the eyes of vipers with and without infrared-sensing pit organs. Biol J Linn Soc Lond 2019. [DOI: 10.1093/biolinnean/blz003] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- David J Gower
- Department of Life Sciences, The Natural History Museum, London, UK
| | - Filipa L Sampaio
- Department of Life Sciences, The Natural History Museum, London, UK
| | - Leo Peichl
- Max Planck Institute for Brain Research, Germany
- Dr. Senckenbergische Anatomie, Goethe University Frankfurt, Germany
| | | | - Ellis R Loew
- Department of Biomedical Sciences, Cornell University, USA
| | - William Mclamb
- Department of Biological Sciences, Florida Institute of Technology, and Center for the Advancement of Science in Space, Melbourne, FL, USA
| | - Ronald H Douglas
- Department of Life Sciences, The Natural History Museum, London, UK
- Department of Optometry and Visual Science, City, University of London, London, UK
| | - Nikolai Orlov
- Department of Herpetology, Zoological Institute, Russian Academy of Sciences, Russia
| | - Michael S Grace
- College of Science, Florida Institute of Technology, Melbourne, FL, USA
| | - Nathan S Hart
- Department of Biological Sciences, Macquarie University, Australia
| | - David M Hunt
- School of Biological Sciences, The University of Western Australia, Australia
- Centre for Ophthalmology and Vision Science, Lions Eye Institute, The University of Western Australia, Perth, Australia
| | - Julian C Partridge
- School of Biological Sciences, The University of Western Australia, Australia
- Oceans Institute, The University of Western Australia, Perth, WA, Australia
| | - Bruno F Simões
- Department of Life Sciences, The Natural History Museum, London, UK
- School of Earth Sciences, University of Bristol, Bristol, UK
- School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia
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9
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Bittencourt GB, Hauzman E, Bonci DMO, Ventura DF. Photoreceptors morphology and genetics of the visual pigments of Bothrops jararaca and Crotalus durissus terrificus (Serpentes, Viperidae). Vision Res 2019; 158:72-77. [PMID: 30826356 DOI: 10.1016/j.visres.2019.02.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 02/11/2019] [Accepted: 02/24/2019] [Indexed: 10/27/2022]
Abstract
Snakes inhabit a great variety of habitats, whose spectral quality of light may vary a lot and influence specific adaptations of their visual system. In this study, we investigated the genetics of the visual opsins and the morphology of retinal photoreceptors, of two nocturnal snakes from the Viperidae family, Bothrops jararaca and Crotalus durissus terrificus, which inhabit preferentially the Atlantic Rain Forest and the Brazilian Savannah, respectively. Total RNA was extracted from homogenized retinas and converted to cDNA. The opsin genes expressed in snake retinas, LWS, RH1, and SWS1, were amplified by polymerase chain reactions (PCRs) and sequenced. The absorption peak (λmax) of the opsins were estimated based on amino acids located at specific spectral tuning sites. Photoreceptor cell populations were analyzed using immunohistochemistry with anti-opsin antibodies. Results showed the same morphological cell populations and same opsins absorption peaks, in both viperid species: double and single cones with LWS photopigment and λmax at ∼555 nm; single cones with SWS1 photopigment and λmax at ∼360 nm; and rods with the rhodopsin RH1 photopigment and λmax at ∼500 nm. The results indicate adaptations to nocturnal habit in both species despite the differences in habitat, and the possibility of a dichromatic color vision at photopic conditions.
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Affiliation(s)
- Guido Barbieri Bittencourt
- Departamento de Psicologia Experimental, Instituto de Psicologia, Universidade de São Paulo, São Paulo, Brazil
| | - Einat Hauzman
- Departamento de Psicologia Experimental, Instituto de Psicologia, Universidade de São Paulo, São Paulo, Brazil; Instituto de Ensino e Pesquisa, Hospital Israelita Albert Einstein, São Paulo, Brazil.
| | - Daniela Maria Oliveira Bonci
- Departamento de Psicologia Experimental, Instituto de Psicologia, Universidade de São Paulo, São Paulo, Brazil; Instituto de Ensino e Pesquisa, Hospital Israelita Albert Einstein, São Paulo, Brazil
| | - Dora Fix Ventura
- Departamento de Psicologia Experimental, Instituto de Psicologia, Universidade de São Paulo, São Paulo, Brazil; Instituto de Ensino e Pesquisa, Hospital Israelita Albert Einstein, São Paulo, Brazil
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10
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Schraft HA, Clark RW. Sensory basis of navigation in snakes: the relative importance of eyes and pit organs. Anim Behav 2019. [DOI: 10.1016/j.anbehav.2018.11.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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11
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Abstract
Although much is known about the visual system of vertebrates in general, studies regarding vision in reptiles, and snakes in particular, are scarce. Reptiles display diverse ocular structures, including different types of retinae such as pure cone, mostly rod, or duplex retinas (containing both rods and cones); however, the same five opsin-based photopigments are found in many of these animals. It is thought that ancestral snakes were nocturnal and/or fossorial, and, as such, they have lost two pigments, but retained three visual opsin classes. These are the RH1 gene (rod opsin or rhodopsin-like-1) expressed in rods and two cone opsins, namely LWS (long-wavelength-sensitive) and SWS1 (short-wavelength-sensitive-1) genes. Until recently, the study of snake photopigments has been largely ignored. However, its importance has become clear within the past few years as studies reconsider Walls’ transmutation theory, which was first proposed in the 1930s. In this study, the visual pigments of Bothrops atrox (the common lancehead), a South American pit viper, were examined. Specifically, full-length RH1 and LWS opsin gene sequences were cloned, as well as most of the SWS1 opsin gene. These sequences were subsequently used for phylogenetic analysis and to predict the wavelength of maximum absorbance (λmax) for each photopigment. This is the first report to support the potential for rudimentary color vision in a South American viper, specifically a species that is regarded as being nocturnal.
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12
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Hauzman E, Bonci DMO, Suárez-Villota EY, Neitz M, Ventura DF. Daily activity patterns influence retinal morphology, signatures of selection, and spectral tuning of opsin genes in colubrid snakes. BMC Evol Biol 2017; 17:249. [PMID: 29228925 PMCID: PMC5725783 DOI: 10.1186/s12862-017-1110-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 12/06/2017] [Indexed: 11/10/2022] Open
Abstract
Background Morphological divergences of snake retinal structure point to complex evolutionary processes and adaptations. The Colubridae family has a remarkable variety of retinal structure that can range from all-cone and all-rod to duplex (cone/rod) retinas. To explore whether nocturnal versus diurnal activity is responsible for constraints on molecular evolution and plays a role in visual opsin spectral tuning of colubrids, we carried out molecular evolution analyses of the visual opsin genes LWS, RH1, and SWS1 from 17 species and performed morphological analyses. Results Phylogenetic reconstructions of the RH1 and LWS recovered major clades characterized by primarily diurnal or primarily nocturnal activity patterns, in contrast with the topology for SWS1, which is very similar to the species tree. We found stronger signals of purifying selection along diurnal and nocturnal lineages for RH1 and SWS1, respectively. A blue-shift of the RH1 spectral peak is associated with diurnal habits. Spectral tuning of cone opsins did not differ among diurnal and nocturnal species. Retinas of nocturnal colubrids had many rows of photoreceptor nuclei, with large numbers of rods, labeled by wheat germ agglutinin (WGA), and two types of cones: large cones sensitive to long/medium wavelengths (L/M) and small cones sensitive to ultra-violet/violet wavelengths (UV/VS). In contrast, retinas of diurnal species had only one row of photoreceptor nuclei, with four types of cones: large and double L/M cones, small UV/VS cones, and a second group of small cones, labeled by WGA. Conclusions For LWS gene, selection tests did not confirm different constraints related to activity pattern. For SWS1, stronger purifying selection in nocturnal lineages indicates divergent evolutionary pressures related to the activity pattern, and the importance of the short wavelength sensitivity at low light condition. Activity pattern has a clear influence on the signatures of selection and spectral tuning of RH1, with stronger purifying selection in diurnal lineages, which indicates selective pressure to preserve rhodopsin structure and function in pure-cone retinas. We suggest that the presence of four cone types in primarily diurnal colubrids might be related to the gain of color discrimination capacity. Electronic supplementary material The online version of this article (10.1186/s12862-017-1110-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- E Hauzman
- Departamento de Psicologia Experimental, Instituto de Psicologia, Universidade de São Paulo, Av. Professor Mello Moraes 1721 Bloco A Sala D9 - Butantã, São Paulo, SP, CEP 05508-030, Brazil. .,Instituto Israelita de Ensino e Pesquisa Albert Einstein, São Paulo, Brazil.
| | - D M O Bonci
- Departamento de Psicologia Experimental, Instituto de Psicologia, Universidade de São Paulo, Av. Professor Mello Moraes 1721 Bloco A Sala D9 - Butantã, São Paulo, SP, CEP 05508-030, Brazil.,Instituto Israelita de Ensino e Pesquisa Albert Einstein, São Paulo, Brazil
| | - E Y Suárez-Villota
- Instituto de Ciencias Marinas y Limnólogicas, Universidad Austral de Chile, Edificio Emilio Pugin, Campus Isla Teja S/N, 5110236, Valdivia, Chile.,Laboratório de Ecologia e Evolução, Instituto Butantan, São Paulo, Brazil
| | - M Neitz
- Department of Opthalmology, University of Washington, 750 Republican Street, Box 358058, Seattle, WA, 98109, USA
| | - D F Ventura
- Departamento de Psicologia Experimental, Instituto de Psicologia, Universidade de São Paulo, Av. Professor Mello Moraes 1721 Bloco A Sala D9 - Butantã, São Paulo, SP, CEP 05508-030, Brazil.,Instituto Israelita de Ensino e Pesquisa Albert Einstein, São Paulo, Brazil
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Emerling CA. Genomic regression of claw keratin, taste receptor and light-associated genes provides insights into biology and evolutionary origins of snakes. Mol Phylogenet Evol 2017; 115:40-49. [PMID: 28739369 DOI: 10.1016/j.ympev.2017.07.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 06/16/2017] [Accepted: 07/13/2017] [Indexed: 01/11/2023]
Abstract
Regressive evolution of anatomical traits often corresponds with the regression of genomic loci underlying such characters. As such, studying patterns of gene loss can be instrumental in addressing questions of gene function, resolving conflicting results from anatomical studies, and understanding the evolutionary history of clades. The evolutionary origins of snakes involved the regression of a number of anatomical traits, including limbs, taste buds and the visual system, and by analyzing serpent genomes, I was able to test three hypotheses associated with the regression of these features. The first concerns two keratins that are putatively specific to claws. Both genes that encode these keratins are pseudogenized/deleted in snake genomes, providing additional evidence of claw-specificity. The second hypothesis is that snakes lack taste buds, an issue complicated by conflicting results in the literature. I found evidence that different snakes have lost one or more taste receptors, but all snakes examined retained at least one gustatory channel. The final hypothesis addressed is that the earliest snakes were adapted to a dim light niche. I found evidence of deleted and pseudogenized genes with light-associated functions in snakes, demonstrating a pattern of gene loss similar to other dim light-adapted clades. Molecular dating estimates suggest that dim light adaptation preceded the loss of limbs, providing some bearing on interpretations of the ecological origins of snakes.
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Bhattacharyya N, Darren B, Schott RK, Tropepe V, Chang BSW. Cone-like rhodopsin expressed in the all cone retina of the colubrid pine snake as a potential adaptation to diurnality. J Exp Biol 2017; 220:2418-2425. [DOI: 10.1242/jeb.156430] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 04/13/2017] [Indexed: 12/12/2022]
Abstract
Colubridae is the largest and most diverse family of snakes, with visual systems that reflect this diversity, encompassing a variety of retinal photoreceptor organizations. The transmutation theory proposed by Walls postulates that photoreceptors could evolutionarily transition between cell types in squamates, but few studies have tested this theory. Recently, evidence for transmutation and rod-like machinery in an all cone retina has been identified in a diurnal garter snake (Thamnophis), and it appears that the rhodopsin gene at least may be widespread among colubrid snakes. However, functional evidence supporting transmutation beyond the existence of the rhodopsin gene remains rare. We examined the all cone retina of another colubrid, Pituophis melanoleucus, thought to be more secretive/burrowing than Thamnophis. We found that P. melanoleucus expresses two cone opsins (SWS1, LWS) and rhodopsin (RH1) within the eye. Immunohistochemistry localized rhodopsin to the outer segment of photoreceptors in the all-cone retina of the snake and all opsin genes produced functional visual pigments when expressed in vitro. Consistent with other studies, we found that P. melanoleucus rhodopsin is extremely blue-shifted. Surprisingly, P. melanoleucus rhodopsin reacted with hydroxylamine, a typical cone opsin characteristic. These results support the idea that the rhodopsin-containing photoreceptors of P. melanoleucus are the products of evolutionary transmutation from rod ancestors, and suggests that this phenomenon may be widespread in colubrid snakes. We hypothesize that transmutation may be an adaptation for diurnal, brighter-light vision, which could result in increased spectral sensitivity and chromatic discrimination with the potential for colour vision.
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Affiliation(s)
- Nihar Bhattacharyya
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Benedict Darren
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Ryan K. Schott
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| | - Vincent Tropepe
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
- Department of Ophthalmology & Vision Sciences, University of Toronto, Toronto ON, M5T 3A9, Canada
- Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada
| | - Belinda S. W. Chang
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
- Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada
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15
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Evolutionary transformation of rod photoreceptors in the all-cone retina of a diurnal garter snake. Proc Natl Acad Sci U S A 2015; 113:356-61. [PMID: 26715746 DOI: 10.1073/pnas.1513284113] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Vertebrate retinas are generally composed of rod (dim-light) and cone (bright-light) photoreceptors with distinct morphologies that evolved as adaptations to nocturnal/crepuscular and diurnal light environments. Over 70 years ago, the "transmutation" theory was proposed to explain some of the rare exceptions in which a photoreceptor type is missing, suggesting that photoreceptors could evolutionarily transition between cell types. Although studies have shown support for this theory in nocturnal geckos, the origins of all-cone retinas, such as those found in diurnal colubrid snakes, remain a mystery. Here we investigate the evolutionary fate of the rods in a diurnal garter snake and test two competing hypotheses: (i) that the rods, and their corresponding molecular machinery, were lost or (ii) that the rods were evolutionarily modified to resemble, and function, as cones. Using multiple approaches, we find evidence for a functional and unusually blue-shifted rhodopsin that is expressed in small single "cones." Moreover, these cones express rod transducin and have rod ultrastructural features, providing strong support for the hypothesis that they are not true cones, as previously thought, but rather are modified rods. Several intriguing features of garter snake rhodopsin are suggestive of a more cone-like function. We propose that these cone-like rods may have evolved to regain spectral sensitivity and chromatic discrimination as a result of ancestral losses of middle-wavelength cone opsins in early snake evolution. This study illustrates how sensory evolution can be shaped not only by environmental constraints but also by historical contingency in forming new cell types with convergent functionality.
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Abramjan A, Bauerová A, Somerová B, Frynta D. Why is the tongue of blue-tongued skinks blue? Reflectance of lingual surface and its consequences for visual perception by conspecifics and predators. Naturwissenschaften 2015; 102:42. [DOI: 10.1007/s00114-015-1293-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 06/30/2015] [Accepted: 07/03/2015] [Indexed: 12/28/2022]
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17
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Simões BF, Sampaio FL, Jared C, Antoniazzi MM, Loew ER, Bowmaker JK, Rodriguez A, Hart NS, Hunt DM, Partridge JC, Gower DJ. Visual system evolution and the nature of the ancestral snake. J Evol Biol 2015; 28:1309-20. [PMID: 26012745 DOI: 10.1111/jeb.12663] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 05/06/2015] [Accepted: 05/18/2015] [Indexed: 11/27/2022]
Abstract
The dominant hypothesis for the evolutionary origin of snakes from 'lizards' (non-snake squamates) is that stem snakes acquired many snake features while passing through a profound burrowing (fossorial) phase. To investigate this, we examined the visual pigments and their encoding opsin genes in a range of squamate reptiles, focusing on fossorial lizards and snakes. We sequenced opsin transcripts isolated from retinal cDNA and used microspectrophotometry to measure directly the spectral absorbance of the photoreceptor visual pigments in a subset of samples. In snakes, but not lizards, dedicated fossoriality (as in Scolecophidia and the alethinophidian Anilius scytale) corresponds with loss of all visual opsins other than RH1 (λmax 490-497 nm); all other snakes (including less dedicated burrowers) also have functional sws1 and lws opsin genes. In contrast, the retinas of all lizards sampled, even highly fossorial amphisbaenians with reduced eyes, express functional lws, sws1, sws2 and rh1 genes, and most also express rh2 (i.e. they express all five of the visual opsin genes present in the ancestral vertebrate). Our evidence of visual pigment complements suggests that the visual system of stem snakes was partly reduced, with two (RH2 and SWS2) of the ancestral vertebrate visual pigments being eliminated, but that this did not extend to the extreme additional loss of SWS1 and LWS that subsequently occurred (probably independently) in highly fossorial extant scolecophidians and A. scytale. We therefore consider it unlikely that the ancestral snake was as fossorial as extant scolecophidians, whether or not the latter are para- or monophyletic.
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Affiliation(s)
- B F Simões
- Department of Life Sciences, The Natural History Museum, London, UK
| | - F L Sampaio
- Department of Life Sciences, The Natural History Museum, London, UK
| | - C Jared
- Laboratório de Biologia Celular, Instituto Butantan, São Paulo, Brazil
| | - M M Antoniazzi
- Laboratório de Biologia Celular, Instituto Butantan, São Paulo, Brazil
| | - E R Loew
- Department of Biomedical Sciences, Cornell University, Ithaca, NY, USA
| | - J K Bowmaker
- Institute of Ophthalmology, University College London, London, UK
| | - A Rodriguez
- Unit of Evolutionary Biology, Zoological Institute, Technical University of Braunschweig, Braunschweig, Germany
| | - N S Hart
- School of Animal Biology and The Oceans Institute, The University of Western Australia, Perth, WA, Australia
| | - D M Hunt
- School of Animal Biology and The Oceans Institute, The University of Western Australia, Perth, WA, Australia.,Lions Eye Institute, University of Western Australia, Perth, WA, Australia
| | - J C Partridge
- School of Animal Biology and The Oceans Institute, The University of Western Australia, Perth, WA, Australia.,School of Biological Sciences, University of Bristol, Bristol, UK
| | - D J Gower
- Department of Life Sciences, The Natural History Museum, London, UK
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Wang FY, Fu WC, Wang IL, Yan HY, Wang TY. The giant mottled eel, Anguilla marmorata, uses blue-shifted rod photoreceptors during upstream migration. PLoS One 2014; 9:e103953. [PMID: 25101636 PMCID: PMC4125165 DOI: 10.1371/journal.pone.0103953] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 07/03/2014] [Indexed: 11/18/2022] Open
Abstract
Catadromous fishes migrate between ocean and freshwater during particular phases of their life cycle. The dramatic environmental changes shape their physiological features, e.g. visual sensitivity, olfactory ability, and salinity tolerance. Anguilla marmorata, a catadromous eel, migrates upstream on dark nights, following the lunar cycle. Such behavior may be correlated with ontogenetic changes in sensory systems. Therefore, this study was designed to identify changes in spectral sensitivity and opsin gene expression of A. marmorata during upstream migration. Microspectrophotometry analysis revealed that the tropical eel possesses a duplex retina with rod and cone photoreceptors. The λmax of rod cells are 493, 489, and 489 nm in glass, yellow, and wild eels, while those of cone cells are 508, and 517 nm in yellow, and wild eels, respectively. Unlike European and American eels, Asian eels exhibited a blue-shifted pattern of rod photoreceptors during upstream migration. Quantitative gene expression analyses of four cloned opsin genes (Rh1f, Rh1d, Rh2, and SWS2) revealed that Rh1f expression is dominant at all three stages, while Rh1d is expressed only in older yellow eel. Furthermore, sequence comparison and protein modeling studies implied that a blue shift in Rh1d opsin may be induced by two known (N83, S292) and four putative (S124, V189, V286, I290) tuning sites adjacent to the retinal binding sites. Finally, expression of blue-shifted Rh1d opsin resulted in a spectral shift in rod photoreceptors. Our observations indicate that the giant mottled eel is color-blind, and its blue-shifted scotopic vision may influence its upstream migration behavior and habitat choice.
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Affiliation(s)
- Feng-Yu Wang
- Taiwan Ocean Research Institute, National Applied Research Laboratories, Kaohsiung, Taiwan
| | - Wen-Chun Fu
- Sensory Physiology Laboratory, Marine Research Station, Academia Sinica, I-Lan County, Taiwan
| | - I-Li Wang
- Chemical Biology and Molecular Biophysics, Taiwan International Graduate Program, Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
| | - Hong Young Yan
- Sensory Physiology Laboratory, Marine Research Station, Academia Sinica, I-Lan County, Taiwan
- Hanse-Wissenschaftskolleg Institute for Advanced Study, Delmenhorst, Germany
| | - Tzi-Yuan Wang
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
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Rocha-Santos GD, Barbier E, Bordignon MO. Sweet trap: Boa constrictor (Serpentes: Boidae) preying on passerines on Cecropia pachystachya (Urticales: Cecropiaceae) in fruiting period. BIOTA NEOTROPICA 2014. [DOI: 10.1590/1676-06032014000314] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Fruits of trumpet tree (Cecropia spp.) attract different species of birds and mammals. Boas (Boa constrictor) are sit-and-wait strategists, able to choose to ambush in microhabitats that are frequently visited by prey. We have seen two events of predation of passerines (Pitangus sulphuratus, Turdus rufiventris) by boas on the same trumpet tree (Cecropiapachystachya) in a remnant of Cerrado, in the city of Campo Grande/MS. These reports may be evidence of strategic association of boas to trumpet trees, considering the density of snakes recorded on the tree and the constant visits by potential prey during fruiting periods. Besides encouraging a more detailed investigation on the strategies of predation by boas, our records constitute relevant information about the snake natural history.
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Affiliation(s)
| | - Eder Barbier
- Universidade Federal de Mato Grosso do Sul, Brasil
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20
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Pérez i de Lanuza G, Font E. Ultraviolet vision in lacertid lizards: evidence from retinal structure, eye transmittance, SWS1 visual pigment genes, and behaviour. J Exp Biol 2014; 217:2899-909. [DOI: 10.1242/jeb.104281] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Abstract
Ultraviolet (UV) vision and UV colour patches have been reported in a wide range of taxa and are increasingly appreciated as an integral part of vertebrate visual perception and communication systems. Previous studies with Lacertidae, a lizard family with diverse and complex coloration, have revealed the existence of UV-reflecting patches that may function as social signals. However, confirmation of the signalling role of UV coloration requires demonstrating that the lizards are capable of vision in the UV waveband. Here we use a multidisciplinary approach to characterize the visual sensitivity of a diverse sample of lacertid species. Spectral transmission measurements of the ocular media show that wavelengths down to 300 nm are transmitted in all the species sampled. Four retinal oil droplet types can be identified in the lacertid retina. Two types are pigmented and two are colourless. Fluorescence microscopy reveals that a type of colourless droplet is UV-transmitting and may thus be associated with UV-sensitive cones. DNA sequencing shows that lacertids have a functional SWS1 opsin, very similar at 13 critical sites to that in the presumed ancestral vertebrate (which was UV-sensitive) and other UV-sensitive lizards. Finally, males of Podarcis muralis are capable of discriminating between two views of the same stimulus that differ only in the presence/absence of UV radiance. Taken together, these results provide convergent evidence of UV vision in lacertids, very likely by means of an independent photopigment. Moreover, the presence of four oil droplet types suggests that lacertids have a four-cone colour vision system.
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21
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Hauzman E, Bonci DM, Grotzner SR, Mela M, Liber AM, Martins SL, Ventura DF. Comparative Study of Photoreceptor and Retinal Ganglion Cell Topography and Spatial Resolving Power in Dipsadidae Snakes. BRAIN, BEHAVIOR AND EVOLUTION 2014; 84:197-213. [DOI: 10.1159/000365275] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Accepted: 06/16/2014] [Indexed: 11/19/2022]
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Abstract
AbstractS cones expressing the short wavelength-sensitive type 1 (SWS1) class of visual pigment generally form only a minority type of cone photoreceptor within the vertebrate duplex retina. Hence, their primary role is in color vision, not in high acuity vision. In mammals, S cones may be present as a constant fraction of the cones across the retina, may be restricted to certain regions of the retina or may form a gradient across the retina, and in some species, there is coexpression of SWS1 and the long wavelength-sensitive (LWS) class of pigment in many cones. During retinal development, SWS1 opsin expression generally precedes that of LWS opsin, and evidence from genetic studies indicates that the S cone pathway may be the default pathway for cone development. With the notable exception of the cartilaginous fishes, where S cones appear to be absent, they are present in representative species from all other vertebrate classes. S cone loss is not, however, uncommon; they are absent from most aquatic mammals and from some but not all nocturnal terrestrial species. The peak spectral sensitivity of S cones depends on the spectral characteristics of the pigment present. Evidence from the study of agnathans and teleost fishes indicates that the ancestral vertebrate SWS1 pigment was ultraviolet (UV) sensitive with a peak around 360 nm, but this has shifted into the violet region of the spectrum (>380 nm) on many separate occasions during vertebrate evolution. In all cases, the shift was generated by just one or a few replacements in tuning-relevant residues. Only in the avian lineage has tuning moved in the opposite direction, with the reinvention of UV-sensitive pigments.
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23
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Olsson M, Stuart-Fox D, Ballen C. Genetics and evolution of colour patterns in reptiles. Semin Cell Dev Biol 2013; 24:529-41. [PMID: 23578866 DOI: 10.1016/j.semcdb.2013.04.001] [Citation(s) in RCA: 118] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 04/02/2013] [Indexed: 10/27/2022]
Abstract
The study of coloration in the polyphyletic reptilians has flourished in the last two decades, in particular with respect to the underlying genetics of colour traits, the function of colours in social interactions, and ongoing selection on these traits in the wild. The taxonomic bias, however, is profound: at this level of resolution almost all available information is for diurnal lizards. Therefore, we focus on case studies, for which there are as complete causal sequences of colour evolution as possible, from phenotypic expression of variation in colour, to ongoing selection in the wild. For work prior to 1992 and for a broader coverage of reptilian coloration we refer the readers to Cooper and Greenburg's (Biology of the Reptilia, 1992) review. There are seven major conclusions we would like to emphasise: (a) visual systems in diurnal lizards are broadly conserved but among the wider range of reptiles in general, there is functionally important variation in the number and type of photoreceptors, spectral tuning of photopigments and optical properties of the eye; (b) coloration in reptiles is a function of complex interactions between structural and pigmentary components, with implications for both proximate control and condition dependence of colour expression; (c) studies of colour-variable species have enabled estimates of heritability of colour and colour patterns, which often show a simple Mendelian pattern of inheritance; (d) colour-polymorphic lizard species sometimes, but not always, show striking differences in genetically encoded reproductive tactics and provide useful models for studying the evolution and maintenance of polymorphism; (e) both male and female colours are sometimes, but not always, a significant component of socio-sexual signalling, often based on multiple traits; (f) evidence for effects of hormones and condition on colour expression, and trade-offs with immunocompetence and parasite load, is variable; (g) lizards show fading of colours in response to physiological stress and ageing and are hence likely to be appropriate models for work on the interactions between handicaps, indicator traits, parasitology and immunoecology.
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Affiliation(s)
- Mats Olsson
- School of Biological Sciences, University of Sydney, Sydney, NSW 2006, Australia.
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24
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DAVIES WAYNEIL, COLLIN SHAUNP, HUNT DAVIDM. Molecular ecology and adaptation of visual photopigments in craniates. Mol Ecol 2012; 21:3121-58. [DOI: 10.1111/j.1365-294x.2012.05617.x] [Citation(s) in RCA: 156] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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25
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Hart NS, Coimbra JP, Collin SP, Westhoff G. Photoreceptor types, visual pigments, and topographic specializations in the retinas of hydrophiid sea snakes. J Comp Neurol 2012; 520:1246-61. [DOI: 10.1002/cne.22784] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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26
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Hárosi FI, Novales Flamarique I. Functional significance of the taper of vertebrate cone photoreceptors. ACTA ACUST UNITED AC 2012; 139:159-87. [PMID: 22250013 PMCID: PMC3269789 DOI: 10.1085/jgp.201110692] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Vertebrate photoreceptors are commonly distinguished based on the shape of their outer segments: those of cones taper, whereas the ones from rods do not. The functional advantages of cone taper, a common occurrence in vertebrate retinas, remain elusive. In this study, we investigate this topic using theoretical analyses aimed at revealing structure–function relationships in photoreceptors. Geometrical optics combined with spectrophotometric and morphological data are used to support the analyses and to test predictions. Three functions are considered for correlations between taper and functionality. The first function proposes that outer segment taper serves to compensate for self-screening of the visual pigment contained within. The second function links outer segment taper to compensation for a signal-to-noise ratio decline along the longitudinal dimension. Both functions are supported by the data: real cones taper more than required for these compensatory roles. The third function relates outer segment taper to the optical properties of the inner compartment whereby the primary determinant is the inner segment’s ability to concentrate light via its ellipsoid. In support of this idea, the rod/cone ratios of primarily diurnal animals are predicted based on a principle of equal light flux gathering between photoreceptors. In addition, ellipsoid concentration factor, a measure of ellipsoid ability to concentrate light onto the outer segment, correlates positively with outer segment taper expressed as a ratio of characteristic lengths, where critical taper is the yardstick. Depending on a light-funneling property and the presence of focusing organelles such as oil droplets, cone outer segments can be reduced in size to various degrees. We conclude that outer segment taper is but one component of a miniaturization process that reduces metabolic costs while improving signal detection. Compromise solutions in the various retinas and retinal regions occur between ellipsoid size and acuity, on the one hand, and faster response time and reduced light sensitivity, on the other.
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Affiliation(s)
- Ferenc I Hárosi
- Laboratory of Sensory Physiology, Marine Biological Laboratory, Woods Hole, MA 02543, USA
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27
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Abstract
The biologist Gordon Walls proposed his "transmutation" theory through the 1930s and the 1940s to explain cone-like morphology of rods (and vice versa) in the duplex retinas of modern-day reptiles, with snakes regarded as the epitome of his hypothesis. Despite Walls' interest, the visual system of reptiles, and in particular snakes, has been widely neglected in favor of studies of fishes and mammals. By analyzing the visual pigments of two henophidian snakes, Xenopeltis unicolor and Python regius, we show that both species express two cone opsins, an ultraviolet-sensitive short-wavelength-sensitive 1 (SWS1) (lambda(max) = 361 nm) pigment and a long-wavelength-sensitive (LWS) (lambda(max) = 550 nm) pigment, providing the potential for dichromatic color vision. They also possess rod photoreceptors which express the usual rod opsin (Rh1) pigment with a lambda(max) at 497 nm. This is the first molecular study of the visual pigments expressed in the photoreceptors of any snake species. The presence of a duplex retina and the characterization of LWS, SWS1, and Rh1 visual pigments in henophidian snakes implies that "lower" snakes do not provide support for Walls' transmutation theory, unlike some "higher" (caenophidian) snakes and other reptiles, such as geckos. More data from other snake lineages will be required to test this hypothesis further.
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28
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Bowmaker JK. Evolution of vertebrate visual pigments. Vision Res 2008; 48:2022-41. [PMID: 18590925 DOI: 10.1016/j.visres.2008.03.025] [Citation(s) in RCA: 223] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2008] [Revised: 03/14/2008] [Accepted: 03/18/2008] [Indexed: 10/21/2022]
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29
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Bakken GS, Krochmal AR. The imaging properties and sensitivity of the facial pits of pitvipers as determined by optical and heat-transfer analysis. ACTA ACUST UNITED AC 2007; 210:2801-10. [PMID: 17690227 DOI: 10.1242/jeb.006965] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
It is commonly assumed that the facial pit of pitvipers forms relatively sharp images and can detect small differences in environmental surface temperatures. We have visualized the temperature contrast images formed on the facial pit membrane using a detailed optical and heat transfer analysis, which includes heat transfer through the air in the pit chambers as well as via thermal infrared radiation. We find the image on the membrane to be poorly focused and of very low temperature contrast. Heat flow through the air in the pit chambers severely limits sensitivity, particularly for small animals with small facial pit chambers. The aperture of the facial pit appears to be larger than is optimal for detecting small targets such as prey at 0.5 m. Angular resolution (i.e. sharpness) and image strength and contrast vary complexly with the size of the pit opening. As a result, the patterns of natural background temperatures obscure prey items and other environmental features, creating false patterns. Consequently, snakes cannot simply target the strongest signal to strike prey. To account for observed behavioral capabilities, the sensory endings on the pit membrane apparently must respond to temperature contrasts of 0.001 degrees C or less. While neural image sharpening likely enhances imaging performance, it appears important for foraging snakes to select ambush sites offering uniform backgrounds and strong thermal contrasts. As the ancestral facial pit was likely less sensitive than the current organ, objects with strong thermal signals, such as habitat features, were needed to drive the evolution of this remarkable sense.
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Affiliation(s)
- George S Bakken
- Department of Ecology and Organismal Biology, Indiana State University, Terre Haute, IN 47809, USA.
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30
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Wilson D, Heinsohn R, Endler JA. The adaptive significance of ontogenetic colour change in a tropical python. Biol Lett 2007; 3:40-3. [PMID: 17443961 PMCID: PMC2373822 DOI: 10.1098/rsbl.2006.0574] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Ontogenetic colour change is typically associated with changes in size, vulnerability or habitat, but assessment of its functional significance requires quantification of the colour signals from the receivers' perspective. The tropical python, Morelia viridis, is an ideal species to establish the functional significance of ontogenetic colour change. Neonates hatch either yellow or red and both the morphs change to green with age. Here, we show that colour change from red or yellow to green provides camouflage from visually oriented avian predators in the different habitats used by juveniles and adults. This reflects changes in foraging behaviour and vulnerability as individuals mature and provides a rare demonstration of the adaptive value of ontogenetic colour change.
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Affiliation(s)
- David Wilson
- Centre for Resource and Environmental Studies, Australian National UniversityCanberra, Australian Capital Territory 0200, Australia
| | - Robert Heinsohn
- Centre for Resource and Environmental Studies, Australian National UniversityCanberra, Australian Capital Territory 0200, Australia
- Author for correspondence ()
| | - John A Endler
- School for Tropical Biology, James Cook UniversityTownsville, Queensland 4811, Australia
- Animal Behaviour Research Group, School of Psychology, Washington Singer Labs, University of ExeterPerry Road, Exeter EX4 4QG, UK
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31
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Hart N, Hunt D. Avian Visual Pigments: Characteristics, Spectral Tuning, and Evolution. Am Nat 2007; 169 Suppl 1:S7-26. [DOI: 10.1086/510141] [Citation(s) in RCA: 236] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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32
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Putz O, Crews D. Embryonic origin of mate choice in a lizard with temperature-dependent sex determination. Dev Psychobiol 2006; 48:29-38. [PMID: 16381031 DOI: 10.1002/dev.20109] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Individual differences in the adult sexual behavior of vertebrates are rooted in the fetal environment. In the leopard gecko (Eublepharis macularius), a species with temperature-dependent sex determination (TSD), hatchling sex ratios differ between incubation temperatures, as does sexuality in same-sex animals. This variation can primarily be ascribed to the temperature having direct organizing actions on the brain. Here we demonstrate that embryonic temperature can affect adult mate choice in the leopard gecko. Given the simultaneous choice between two females from different incubation temperatures (30.0 and 34.0 degrees C), males from one incubation temperature (30.0 degrees C) preferred the female from 34.0 degrees C, while males from another incubation temperature (32.5 degrees C) preferred the female from 30.0 degrees C. We suggest that this difference in mate choice is due to an environmental influence on brain development leading to differential perception of opposite-sex individuals. This previously unrecognized modulator of adult mate choice lends further support to the view that mate choice is best understood in the context of an individual's entire life-history. Thus, sexual selection results from a combination of the female's as well as the male's life history. Female attractiveness and male choice therefore are complementary.
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Affiliation(s)
- Oliver Putz
- Section for Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
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STUART-FOX DEVI, WHITING MARTINJ, MOUSSALLI ADNAN. Camouflage and colour change: antipredator responses to bird and snake predators across multiple populations in a dwarf chameleon. Biol J Linn Soc Lond 2006. [DOI: 10.1111/j.1095-8312.2006.00631.x] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Osorio D, Vorobyev M. Photoreceptor spectral sensitivities in terrestrial animals: adaptations for luminance and colour vision. Proc Biol Sci 2006; 272:1745-52. [PMID: 16096084 PMCID: PMC1559864 DOI: 10.1098/rspb.2005.3156] [Citation(s) in RCA: 271] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
This review outlines how eyes of terrestrial vertebrates and insects meet the competing requirements of coding both spatial and spectral information. There is no unique solution to this problem. Thus, mammals and honeybees use their long-wavelength receptors for both achromatic (luminance) and colour vision, whereas flies and birds probably use separate sets of photoreceptors for the two purposes. In particular, we look at spectral tuning and diversification among 'long-wavelength' receptors (sensitivity maxima at greater than 500 nm), which play a primary role in luminance vision. Data on spectral sensitivities and phylogeny of visual photopigments can be incorporated into theoretical models to suggest how eyes are adapted to coding natural stimuli. Models indicate, for example, that animal colour vision--involving five or fewer broadly tuned receptors--is well matched to most natural spectra. We can also predict that the particular objects of interest and signal-to-noise ratios will affect the optimal eye design. Nonetheless, it remains difficult to account for the adaptive significance of features such as co-expression of photopigments in single receptors, variation in spectral sensitivities of mammalian L-cone pigments and the diversification of long-wavelength receptors that has occurred in several terrestrial lineages.
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Affiliation(s)
- D Osorio
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK.
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Sillman AJ, Dahlin DA. Photoreceptor topography in the duplex retina of the paddlefish (Polyodon spathula). JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, COMPARATIVE EXPERIMENTAL BIOLOGY 2004; 301:674-81. [PMID: 15286947 DOI: 10.1002/jez.a.63] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Retinal whole-mount preparations from the eyes of the North American paddlefish, Polyodon spathula, were examined with a combination of bright field and differential interference contrast microscopy. The entire retina was mapped and population counts of rod and cone photoreceptors were made at regular intervals throughout the retina. The retina is dominated by rods, but a significant percentage (ca. 38%) of the photoreceptors are cones. Mean cone packing density for the entire retina is 6,402+/-1,216 cones/mm2. There is a small (16%) but statistically significant difference between cone packing density in the dorsal retina (6,674+/-1,168 cones/mm2) and the ventral retina (5,745+/-1,076 cones/mm2). There is no region of unusually high cone concentration that might be construed as a fovea or a visual streak. Mean rod packing density for the entire retina is 10,271+/-1,205 rods/mm2. Except in the far periphery, where rods are less numerous, the density of rods is fairly uniform throughout the retina. The data are discussed with regard to paddlefish habitat and behavior.
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Affiliation(s)
- Arnold J Sillman
- Section of Neurobiology, Physiology, and Behavior, Division of Biological Sciences, University of California, Davis, California 95616, USA.
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