Evolution of color vision

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Color vision, a proximate adaptation of the vision sensory modality, allows for the discrimination of light based on its wavelength components.

Contents

Improved detection sensitivity

The evolutionary process of switching from a single photopigment to two different pigments would have provided early ancestors with a sensitivity advantage in two ways.

In one way, adding a new pigment would allow them to see a wider range of the electromagnetic spectrum. Secondly, new random connections would create wavelength opponency and the new wavelength opponent neurons would be much more sensitive than the non-wavelength opponent neurons. This is the result of some wavelength distributions favouring excitation instead of inhibition. Both excitation and inhibition would be features of a neural substrate during the formation of a second pigment. Overall, the advantage gained from increased sensitivity with wavelength opponency would open up opportunities for future exploitation by mutations and even further improvement. [1]

Invertebrates

Color vision requires a number of opsin molecules with different absorbance peaks, and at least three opsins were present in the ancestor of arthropods; chelicerates and pancrustaceans today possess color vision. [2]

Vertebrates

Researchers studying the opsin genes responsible for color-vision pigments have long known that four photopigment opsins exist in birds, reptiles and teleost fish. [3] This indicates that the common ancestor of amphibians and amniotes (≈350 million years ago) had tetrachromatic vision — the ability to see four dimensions of color. [4]

Mammals

Today, most mammals possess dichromatic vision, corresponding to protanopia red–green color blindness. They can thus see violet, blue, green and yellow light, but cannot see ultraviolet or deep red light. [5] [6] This was probably a feature of the first mammalian ancestors, which were likely small, nocturnal, and burrowing.

At the time of the Cretaceous–Paleogene extinction event 66 million years ago, the burrowing ability probably helped mammals survive extinction. Mammalian species of the time had already started to differentiate, but were still generally small, comparable in size to shrews; this small size would have helped them to find shelter in protected environments.

Monotremes and marsupials

It is postulated that some early monotremes, marsupials, and placentals were semiaquatic or burrowing, as there are multiple mammalian lineages with such habits today. Any burrowing or semiaquatic mammal would have had additional protection from Cretaceous–Paleogene boundary environmental stresses. [7] However, many such species evidently possessed poor color vision in comparison with non-mammalian vertebrate species of the time, including reptiles, birds, and amphibians.

Primates

Since the beginning of the Paleogene Period, surviving mammals enlarged, moving away by adaptive radiation from a burrowing existence and into the open, although most species kept their relatively poor color vision. Exceptions occur for some marsupials (which possibly kept their original color vision) and some primates—including humans. Primates, as an order of mammals, began to emerge around the beginning of the Paleogene Period.

Primates have re-developed trichromatic color vision since that time, by the mechanism of gene duplication, being under unusually high evolutionary pressure to develop color vision better than the mammalian standard. Ability to perceive red [8] and orange hues allows tree-dwelling primates to discern them from green. This is particularly important for primates in the detection of red and orange fruit, as well as nutrient-rich new foliage, in which the red and orange carotenoids have not yet been masked by chlorophyll.

Another theory is that detecting skin flushing and thereby mood may have influenced the development of primate trichromate vision. The color red also has other effects on primate and human behavior, as discussed in the color psychology article. [9]

Today, among simians, the catarrhines (Old World monkeys and apes, including humans) are routinely trichromatic—meaning that both males and females possess three opsins, sensitive to short-wave, medium-wave, and long-wave light [4] —while, conversely, only a small fraction of platyrrhine primates (New World monkeys) are trichromats. [10]

Timeline

A new study published in Biological Reviews proposes that animal color vision emerged approximately 500 million years ago. This timeline precedes the emergence of many brightly colored organisms, such as flowering plants, colorful vertebrates, and arthropods. The study suggests that the ability to perceive color developed before the widespread appearance of colorful stimuli in the environment. [11]

This discovery has generated interest and discussion among scientists because it raises important questions about the evolutionary pressures that led to the development of color vision. Early forms of color vision may have been utilized for activities such as foraging, mate choice, or avoiding predators, even in a less colorful world. [11]

See also

Related Research Articles

<span class="mw-page-title-main">Visible spectrum</span> Portion of the electromagnetic spectrum that is visible to the human eye

The visible spectrum is the band of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light . The optical spectrum is sometimes considered to be the same as the visible spectrum, but some authors define the term more broadly, to include the ultraviolet and infrared parts of the electromagnetic spectrum as well, known collectively as optical radiation.

<span class="mw-page-title-main">Eye</span> Organ that detects light and converts it into electro-chemical impulses in neurons

An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system.

<span class="mw-page-title-main">Color vision</span> Ability to perceive differences in light frequency

Color vision, a feature of visual perception, is an ability to perceive differences between light composed of different frequencies independently of light intensity.

<span class="mw-page-title-main">New World monkey</span> Parvorder of mammals

New World monkeys are the five families of primates that are found in the tropical regions of Mexico, Central and South America: Callitrichidae, Cebidae, Aotidae, Pitheciidae, and Atelidae. The five families are ranked together as the Ceboidea, the only extant superfamily in the parvorder Platyrrhini.

<span class="mw-page-title-main">Tetrachromacy</span> Type of color vision with four types of cone cells

Tetrachromacy is the condition of possessing four independent channels for conveying color information, or possessing four types of cone cell in the eye. Organisms with tetrachromacy are called tetrachromats.

<span class="mw-page-title-main">Trichromacy</span> Possessing of three independent channels for conveying color information

Trichromacy or trichromatism is the possession of three independent channels for conveying color information, derived from the three different types of cone cells in the eye. Organisms with trichromacy are called trichromats.

In visual physiology, adaptation is the ability of the retina of the eye to adjust to various levels of light. Natural night vision, or scotopic vision, is the ability to see under low-light conditions. In humans, rod cells are exclusively responsible for night vision as cone cells are only able to function at higher illumination levels. Night vision is of lower quality than day vision because it is limited in resolution and colors cannot be discerned; only shades of gray are seen. In order for humans to transition from day to night vision they must undergo a dark adaptation period of up to two hours in which each eye adjusts from a high to a low luminescence "setting", increasing sensitivity hugely, by many orders of magnitude. This adaptation period is different between rod and cone cells and results from the regeneration of photopigments to increase retinal sensitivity. Light adaptation, in contrast, works very quickly, within seconds.

Dichromacy is the state of having two types of functioning photoreceptors, called cone cells, in the eyes. Organisms with dichromacy are called dichromats. Dichromats require only two primary colors to be able to represent their visible gamut. By comparison, trichromats need three primary colors, and tetrachromats need four. Likewise, every color in a dichromat's gamut can be evoked with monochromatic light. By comparison, every color in a trichromat's gamut can be evoked with a combination of monochromatic light and white light.

<span class="mw-page-title-main">Monochromacy</span> Type of color vision

Monochromacy is the ability of organisms to perceive only light intensity without respect to spectral composition. Organisms with monochromacy lack color vision and can only see in shades of grey ranging from black to white. Organisms with monochromacy are called monochromats. Many mammals, such as cetaceans, the owl monkey and the Australian sea lion are monochromats. In humans, monochromacy is one among several other symptoms of severe inherited or acquired diseases, including achromatopsia or blue cone monochromacy, together affecting about 1 in 30,000 people.

<span class="mw-page-title-main">Melanopsin</span> Mammalian protein found in Homo sapiens

Melanopsin is a type of photopigment belonging to a larger family of light-sensitive retinal proteins called opsins and encoded by the gene Opn4. In the mammalian retina, there are two additional categories of opsins, both involved in the formation of visual images: rhodopsin and photopsin in the rod and cone photoreceptor cells, respectively.

<span class="mw-page-title-main">Opsin</span> Class of light-sensitive proteins

Animal opsins are G-protein-coupled receptors and a group of proteins made light-sensitive via a chromophore, typically retinal. When bound to retinal, opsins become retinylidene proteins, but are usually still called opsins regardless. Most prominently, they are found in photoreceptor cells of the retina. Five classical groups of opsins are involved in vision, mediating the conversion of a photon of light into an electrochemical signal, the first step in the visual transduction cascade. Another opsin found in the mammalian retina, melanopsin, is involved in circadian rhythms and pupillary reflex but not in vision. Humans have in total nine opsins. Beside vision and light perception, opsins may also sense temperature, sound, or chemicals.

<span class="mw-page-title-main">OPN1SW</span> Protein-coding gene in the species Homo sapiens

Blue-sensitive opsin is a protein that in humans is encoded by the OPN1SW gene.

<span class="mw-page-title-main">OPN1MW</span> Protein-coding gene in the species Homo sapiens

Green-sensitive opsin is a protein that in humans is encoded by the OPN1MW gene. OPN1MW2 is a similar opsin.

<span class="mw-page-title-main">OPN1LW</span> Protein-coding gene in humans

OPN1LW is a gene on the X chromosome that encodes for long wave sensitive (LWS) opsin, or red cone photopigment. It is responsible for perception of visible light in the yellow-green range on the visible spectrum. The gene contains 6 exons with variability that induces shifts in the spectral range. OPN1LW is subject to homologous recombination with OPN1MW, as the two have very similar sequences. These recombinations can lead to various vision problems, such as red-green colourblindness and blue monochromacy. The protein encoded is a G-protein coupled receptor with embedded 11-cis-retinal, whose light excitation causes a cis-trans conformational change that begins the process of chemical signalling to the brain.

<span class="mw-page-title-main">Evolution of color vision in primates</span> Loss and regain of colour vision during the evolution of primates

The evolution of color vision in primates is highly unusual compared to most eutherian mammals. A remote vertebrate ancestor of primates possessed tetrachromacy, but nocturnal, warm-blooded, mammalian ancestors lost two of four cones in the retina at the time of dinosaurs. Most teleost fish, reptiles and birds are therefore tetrachromatic while most mammals are strictly dichromats, the exceptions being some primates and marsupials, who are trichromats, and many marine mammals, who are monochromats.

<span class="mw-page-title-main">Blindness in animals</span> Animals with limited visual perception

Visual perception in animals plays an important role in the animal kingdom, most importantly for the identification of food sources and avoidance of predators. For this reason, blindness in animals is a unique topic of study.

Gene therapy for color blindness is an experimental gene therapy of the human retina aiming to grant typical trichromatic color vision to individuals with congenital color blindness by introducing typical alleles for opsin genes. Animal testing for gene therapy began in 2007 with a 2009 breakthrough in squirrel monkeys suggesting an imminent gene therapy in humans. While the research into gene therapy for red-green colorblindness has lagged since then, successful human trials are ongoing for achromatopsia. Congenital color vision deficiency affects upwards of 200 million people in the world, which represents a large demand for this gene therapy.

<span class="mw-page-title-main">Nocturnal bottleneck</span> Hypothesis to explain traits in mammals

The nocturnal bottleneck hypothesis is an evolutionary biology hypothesis to explain the origin of several mammalian traits. In 1942, Gordon Lynn Walls described this concept which states that placental mammals were mainly or even exclusively nocturnal through most of their evolutionary history, from their origin 225 million years ago during the Late Triassic to after the Cretaceous–Paleogene extinction event, 66 million years ago. While some mammalian groups later adapted to diurnal (daytime) lifestyles to fill niches newly vacated by the extinction of non-avian dinosaurs, the approximately 160 million years spent as nocturnal animals has left a lasting legacy on basal mammalian anatomy and physiology, and most mammals are still nocturnal.

<span class="mw-page-title-main">Congenital red–green color blindness</span> Most common genetic condition leading to color blindness

Congenital red–green color blindness is an inherited condition that is the root cause of the majority of cases of color blindness. It has no significant symptoms aside from its minor to moderate effect on color vision. It is caused by variation in the functionality of the red and/or green opsin proteins, which are the photosensitive pigment in the cone cells of the retina, which mediate color vision. Males are more likely to inherit red–green color blindness than females, because the genes for the relevant opsins are on the X chromosome. Screening for congenital red–green color blindness is typically performed with the Ishihara or similar color vision test. It is a lifelong condition, and has no known cure or treatment.

<span class="mw-page-title-main">Vertebrate visual opsin</span>

Vertebrate visual opsins are a subclass of ciliary opsins and mediate vision in vertebrates. They include the opsins in human rod and cone cells. They are often abbreviated to opsin, as they were the first opsins discovered and are still the most widely studied opsins.

References

  1. ↑ Gagin, G.; Bohon, K. S.; Butensky, A.; Gates, M. A.; Hu, J-Y.; Lafer-Sousa, R.; Pulumo, R. L.; Qu, J.; Stoughton, C. M.; Swanbeck, S. N.; Conway, B. R. (2014). "Color-detection thresholds in rhesus macaque monkeys and humans". Journal of Vision. 14 (8): 12–26. doi:10.1167/14.8.12. PMC   4528409 . PMID   25027164.
  2. ↑ Koyanagi, M.; Nagata, T.; Katoh, K.; Yamashita, S.; Tokunaga, F. (2008). "Molecular Evolution of Arthropod Color Vision Deduced from Multiple Opsin Genes of Jumping Spiders". Journal of Molecular Evolution. 66 (2): 130–137. Bibcode:2008JMolE..66..130K. doi:10.1007/s00239-008-9065-9. PMID   18217181. S2CID   23837628.
  3. ↑ Yokoyama, S., and B. F. Radlwimmer. 2001. The molecular genetics and evolution of red and green color vision in vertebrates. Genetics Society of America. 158: 1697-1710.
  4. 1 2 Bowmaker, J. K. (1998). "Evolution of colour vision in vertebrates". Eye. 12 (3b): 541–547. doi: 10.1038/eye.1998.143 . PMID   9775215. S2CID   12851209.
  5. ↑ Carroll, Joseph; Murphy, Christopher J.; Neitz, Maureen; Hoeve, James N. Ver; Neitz, Jay (1 August 2001). "Photopigment basis for dichromatic color vision in the horse". Journal of Vision. 1 (2): 80–87. doi: 10.1167/1.2.2 . PMID   12678603 . Retrieved 23 April 2018– via jov.arvojournals.org.
  6. ↑ "Archived copy" (PDF). Archived from the original (PDF) on 2015-08-07. Retrieved 2015-06-29.{{cite web}}: CS1 maint: archived copy as title (link)
  7. ↑ Robertson DS, McKenna MC, Toon OB, Hope S, Lillegraven JA (2004). "Survival in the first hours of the Cenozoic" (PDF). GSA Bulletin. 116 (5–6): 760–768. Bibcode:2004GSAB..116..760R. doi:10.1130/B25402.1 . Retrieved 2016-01-06.
  8. ↑ Dulai, K. S.; von Dornum, M.; Mollon, J. D.; Hunt, D. M. (1999). "The evolution of trichromatic color vision by opsin gene duplication in New World and Old World primates". Genome Research. 9 (7): 629–638. doi: 10.1101/gr.9.7.629 . PMID   10413401. S2CID   10637615.
  9. ↑ Diana Widermann, Robert A. Barton, and Russel A. Hill. Evolutionary perspectives on sport and competition. In Roberts, S. C. (2011). Roberts, S. Craig (ed.). Applied Evolutionary Psychology. Oxford University Press. doi:10.1093/acprof:oso/9780199586073.001.0001. ISBN   978-0-19-958607-3.
  10. ↑ Surridge, A. K., and D. Osorio. 2003. Evolution and selection of trichromatic vision in primates. Trends in Ecol. and Evol. 18: 198-205.
  11. 1 2 Novak, Sara (2024-12-12). "Which Came First, Color Vision or Colorful Things?". Scientific American. Retrieved 2024-12-13.
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