ArticleProceedings of the National Academy of Sciences of the United States of America2016
Evolutionary transformation of rod photoreceptors in the all-cone retina of a diurnal garter snake.
Article in Proceedings of the National Academy of Sciences of the United States of America, 2016. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 30 papers.
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30 citing papers in PubMed, 93 citations in OpenAlex.
- Evolutionary Shifts in Rhodopsin Function Illuminate Dim-Light Adaptations in Birds.Integrative zoology · 2026Article
- Comparative Retinal Morphology of Two Sympatric Lizard Species from Distinct Microhabitats.Animals : an open access journal from MDPI · 2026Article
- Canonical PKCα-immunoreactive rod bipolar cells are present in nocturnal snakes but not in diurnal snakes.Scientific reports · 2026Article
- Deep-sea fish reveal an alternative developmental trajectory for vertebrate vision.Science advances · 2026Article
- Exceptional Visual-Opsin Coexpression and Phenotypic Diversity in Outer-Retinal Photoreceptors of Caenophidian Snakes.The Journal of comparative neurology · 2025Article
- Adaptations of the Vertebrate Retina to Low-Light Conditions: A Review.Anatomia, histologia, embryologia · 2025Review
- Camouflage, conspicuousness, and inducible color change in a polymorphic, sexually dichromatic frog.Integrative organismal biology (Oxford, England) · 2025Article
- Diversity and Evolution of Frog Visual Opsins: Spectral Tuning and Adaptation to Distinct Light Environments.Molecular biology and evolution · 2024Article
- Selection on Visual Opsin Genes in Diurnal Neotropical Frogs and Loss of the SWS2 Opsin in Poison Frogs.Molecular biology and evolution · 2023Article
- Ultrastructural Characteristics and Synaptic Connectivity of Photoreceptors in the Simplex Retina of Little Skate (eNeuro · 2023Article
- The evolutionary history and spectral tuning of vertebrate visual opsins.Developmental biology · 2023Review
- Enhanced short-wavelength sensitivity in the blue-tongued skink Tiliqua rugosa.The Journal of experimental biology · 2022Article
- Evolutionary analyses of visual opsin genes in frogs and toads: Diversity, duplication, and positive selection.Ecology and evolution · 2022Article
- Simultaneous Expression of UV and Violet SWS1 Opsins Expands the Visual Palette in a Group of Freshwater Snakes.Molecular biology and evolution · 2021Article
- Eye-Transcriptome and Genome-Wide Sequencing for Scolecophidia: Implications for Inferring the Visual System of the Ancestral Snake.Genome biology and evolution · 2021Article
- Evolutionary adaptation of visual pigments in geckos for their photic environment.Science advances · 2021Article
- Interphotoreceptor coupling: an evolutionary perspective.Pflugers Archiv : European journal of physiology · 2021Review
- Morphological Plasticity of the Retina of Viperidae Snakes Is Associated With Ontogenetic Changes in Ecology and Behavior.Frontiers in neuroanatomy · 2021Article
- Article
- Visual adaptation of opsin genes to the aquatic environment in sea snakes.BMC evolutionary biology · 2020Article
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Authors and funding
11 authors at 3 institutions in 3 countries.
Funding
No grant is acknowledged in the PubMed record.
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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