Editing Melanism

{{Short description|Congenital excess of melanin in an organism resulting in dark pigment}}
[[File:melsquir.jpg|thumb|[[Black squirrel|Melanistic black]] [[eastern grey squirrel]] (''Sciurus carolinensis'')]]
[[File:Cavia porcellus-Licorice.jpg|thumb|Melanistic [[guinea pig]]s (''Cavia porcellus'') are rare, and are used in rituals by Andean ''[[curandero]]s''.<ref>{{cite book |last=Morales |first=E. |title=The Guinea Pig : Healing, Food, and Ritual in the Andes |publisher=University of Arizona Press |year=1995 |isbn=0-8165-1558-1}}</ref>]]

'''Melanism''' is the [[Birth defect|congenital]] excess of [[melanin]] in an organism resulting in dark [[Biological pigment|pigment]].

Pseudomelanism, also called abundism, is another variant of pigmentation, identifiable by dark spots or enlarged stripes, which cover a large part of the body of the animal, making it appear melanistic.<ref>{{cite journal |last1=Osinga |first1=N. |last2=Hart |first2=P. |last3=van VoorstVaader |first3=P. C. |year=2010 |title=Albinistic common seals (''Phoca vitulina'') and melanistic grey seals (''Halichoerus grypus'') rehabilitated in the Netherlands |journal=Animal Biology |volume=60 |issue=3 |pages=273−281 |doi= 10.1163/157075610x516493|s2cid=84554567 }}</ref>

The morbid deposition of black matter, often of a malignant character causing pigmented [[tumor]]s, is called [[melanosis]].<ref>Webster's Revised Unabridged Dictionary (1913). [http://machaut.uchicago.edu/?resource=Webster%27s&word=melanosis&use1913=on&use1828=on ''Melanosis''] {{webarchive|url=https://web.archive.org/web/20130729213810/http://machaut.uchicago.edu/?resource=Webster%27s&word=melanosis&use1913=on&use1828=on |date=2013-07-29 }}. C. & G. Merriam Co. Springfield, Massachusetts. Page 910</ref>

==Adaptation==
[[File:Hugorme.jpg|thumb|right|A melanistic [[European adder]] (''Vipera berus'') compared to a normal-colored adder]]
Melanism related to the process of [[adaptation]] is called adaptive. Most commonly, dark individuals become [[Fitness (biology)|fitter]] to survive and reproduce in their environment as they are better camouflaged. This makes some species less conspicuous to predators, while others, such as [[leopards]], use it as a foraging advantage during night hunting.<ref>King, R.C., Stansfield, W.D., Mulligan, P.K. (2006). ''A Dictionary of Genetics'', 7th ed., Oxford University Press</ref> Typically, adaptive melanism is [[Heritability|heritable]]: A [[Dominance (genetics)|dominant]] [[allele]], which is entirely or nearly entirely expressed in the [[phenotype]], is responsible for the excessive amount of melanin. By contrast, adaptive melanism associated with Batesian mimicry in [[Zelandoperla fenestrata]] [[stoneflies]] is controlled by a [[recessive allele]] at the ebony locus.<ref name="Ni et al.">{{cite journal |last1=Ni |first1=Steven |last2=McCulloch |first2=Graham |last3=Kroos |first3=Gracie |last4=King |first4=Tania |last5=Dutoit |first5=Ludovic |last6=Foster |first6=Brodie |last7=Hema |first7=Kahu |last8=Jandt |first8=Jennifer |last9=Peng |first9=Mei |last10=Dearden |first10=Peter |last11=Waters |first11=Jonathan |title=Human-driven evolution of color in a stonefly mimic |journal=Science |volume=386 |issue=6720|pages=453-458 |doi=10.1126/science.ado5331}}</ref><ref name ="Foster et al.">{{cite journal |last1=Foster |first1=Brodie |last2=McCulloch |first2=Graham |last3=Foster |first3=Yasmin |last4=Kroos |first4=Gracie |last5=King |first5=Tania |last6=Waters |first6=Jonathan |title=ebony underpins Batesian mimicry in melanic stoneflies |journal=Molecular Ecology |volume=32 |issue=18 |pages=4986-4998 |doi=10.1111/mec.17085|doi-access=free }}</ref>

Adaptive melanism has been shown to occur in a variety of animals, including mammals such as [[squirrel]]s, many [[Felidae|cats]] and [[canid]]s, and [[coral snake]]s. Adaptive melanism can lead to the creation of [[Polymorphism (biology)|morphs]], a notable example being the [[peppered moth]], whose evolutionary history in the [[United Kingdom]] is offered as a classic instructional tool for teaching the principles of [[natural selection]].<ref>{{cite book |author=Begon, M. |name-list-style=amp |author2=Townsend, C. R. |author3=Harper, J. L. |year=2006 |title=Ecology: From individuals to ecosystems |location=Malden, Oxford |publisher=Wiley Publishing |edition=Fourth |isbn= 9781405151986 |url=https://books.google.com/books?id=Lsf1lkYKoHEC&pg=PA9}}</ref> A more replicated example of human-induced shifts in [[melanism]] has arisen from repeated selection against melanic [[Zelandoperla fenestrata]] stonefly phenotypes following widespread [[deforestation in New Zealand]].<ref name="Ni et al." /><ref name="Foster et al." />

===Industrial melanism===
{{main|Industrial melanism}}

Industrial melanism is an [[evolution]]ary effect in insects such as the peppered moth, ''[[Biston betularia]]'' in areas subject to [[industrial pollution]]. Darker pigmented individuals are favored by [[natural selection]], apparently because they are better [[camouflage]]d against polluted backgrounds. When pollution was later reduced, lighter forms regained the advantage and melanism became less frequent.<ref>Majerus, M. E. (2009). Industrial melanism in the peppered moth, Biston betularia: an excellent teaching example of Darwinian evolution in action. Evolution: Education and Outreach, 2(1), 63–74.</ref><ref>McIntyre, N. E. (2000). Ecology of urban arthropods: a review and a call to action. Annals of the Entomological Society of America, 93(4), 825–835.</ref><ref>Cook, L. M., Saccheri, I. J., 2013. The peppered moth and industrial melanism: evolution of a natural selection case study. Journal of Heredity 110:207–12</ref><ref name=":3">Grant, B. S., Wiseman L. L., 2002. Recent history of melanism in American peppered moths. Journal of Heredity 93:86-90.</ref><ref>Brakefield, P. M., Liebert, T. G., 2000. Evolutionary dynamics of declining melanism in the peppered moth in the Netherlands. Proceedings of the Royal Society of London Biology 267:1953–1957.</ref><ref name="Grant, B. S. 1998">Grant, B. S., Cook, A. D., Clarke, C. A., & Owen, D. F. (1998). Geographic and temporal variation in the incidence of melanism in peppered moth populations in America and Britain. ''Journal of Heredity'', 89(5), 465–471.</ref> Other explanations have been proposed, such as that the melanin pigment enhances function of immune defences,<ref>Mikkola, K., & Rantala, M. J. (2010). Immune defence, a possible nonvisual selective factor behind the industrial melanism of moths (Lepidoptera). Biological Journal of the Linnean Society, 99(4), 831–838.</ref> or a thermal advantage from the darker coloration.<ref name=":0">Mikkola, K., Albrecht, A., 1988. The melanism of ''Adalia-bipunctata'' around the Gulf of Finland as an industrial phenomenon (Coleoptera, Coccinellidae). Annales Zoologici Fennici 25:177–85.</ref><ref name=":1">Muggleton, J., Lonsdale, D., Benham, B. R., 1975. Melanism in ''Adalia-bipunctata L'' (ColCoccinellidae) and its relationship to atmospheric pollution. Journal of Applied Ecology 2:451–464.</ref><ref name=":2">De Jong, P. W., Verhoog, M. D., Brakefield, P. M., 1992. Sperm competition and melanic polymorphism in the 2-spot ladybird, ''Adalla bipunctata'' (Coleoptera, Coccinellidae). Journal of Heredity 70:172–178.</ref>

==In cats==
{{see also|Black cat}}
[[File:Melanism in Panthera Onca.jpg|thumb|Melanistic and normally coloured jaguars]]
Melanistic coat coloration occurs as a common [[Polymorphism (biology)|polymorphism]] in 11 of 37 [[felid]] species and reaches high population frequency in some cases but never achieves complete [[Fixation (population genetics)|fixation]]. The [[black panther]], a melanistic [[leopard]], is common in the [[equatorial rainforest]] of [[Malay Peninsula|Malaya]] and the [[tropical rainforest]] on the slopes of some African mountains, such as [[Mount Kenya]]. The [[serval]] also has melanistic forms in certain areas of [[East Africa]]. In the [[jaguarundi]], coloration varies from dark brown and gray to light reddish. Melanic forms of [[jaguar]] are common in certain parts of [[South America]].<ref>Searle, A. G. (1968) ''Comparative Genetics of Coat Colour in Mammals''. Logos Press, London</ref> In 1938 and 1940, two melanistic [[bobcat]]s were trapped alive in sub-tropical [[Florida]].<ref>Ulmer, F. A. (1941) ''Melanism in the Felidae, with special reference to the Genus Lynx''. Journal of Mammalogy 22 (3): 285–288.</ref>
[[File:Acinonyx jubatus King Cheetah.jpg|thumb|Pseudomelanism on a [[cheetah]]]]
[[File:Melanistic eastern gray squirrel 2.jpg|alt=Melanistic eastern gray squirrel|thumb|Melanistic eastern gray squirrel]]
In 2003, the [[dominance (genetics)|dominant]] mode of inheritance of melanism in jaguars was confirmed by performing [[phenotype]]-transmission analysis in a 116-individual captive [[Purebred|pedigree]]. Melanistic animals were found to carry at least one copy of a mutant ''[[MC1R]]'' sequence [[allele]], bearing a 15-[[base pair]] inframe deletion. Ten unrelated melanistic jaguars were either [[homozygous]] or [[heterozygous]] for this allele. A 24-base pair deletion causes the incompletely dominant allele for melanism in the jaguarundi. Sequencing of the [[agouti signalling peptide]] in the [[agouti gene]] coding region revealed a 2-base pair deletion in black [[domestic cat]]s. These variants were absent in melanistic individuals of [[Geoffroy's cat]], [[oncilla]], [[pampas cat]] and [[Asian golden cat]], suggesting that melanism arose independently at least four times in the cat family.<ref name="Eizirik03">{{cite journal |author1=Eizirik, E. |author2=Yuhki, N. |author3=Johnson, W. E. |author4=Menotti-Raymond, M. |author5=Hannah, S. S. |author6=O'Brien, S. J. |title=Molecular Genetics and Evolution of Melanism in the Cat Family |journal=Current Biology |year=2003 |volume=13 |issue=5 |pages=448–453 |doi=10.1016/S0960-9822(03)00128-3 |pmid=12620197 |s2cid=19021807 |doi-access=free }}</ref>

Melanism in leopards is inherited as a [[Mendelian trait|Mendelian]], [[Monogenic (genetics)|monogenic]] [[recessive trait]] relative to the spotted form. Pairings of black animals have a significantly smaller litter size than other possible pairings.<ref>{{cite journal |author=Robinson, R. |year=1970 |title=Inheritance of black form of the leopard ''Panthera pardus'' |journal=Genetica |volume=41 |issue=1 |pages=190–197 |doi=10.1007/BF00958904 |pmid=5480762|s2cid=5446868 }}</ref> Between January 1996 and March 2009, [[Indochinese leopard]]s were photographed at 16 sites in the [[Malay Peninsula]] in a sampling effort of more than 1000 trap nights. Of 445 photographs of melanistic leopards, 410 were taken south of the [[Kra Isthmus]], where the non-melanistic morph was never photographed. These data suggest the near fixation of the dark allele in the region. The expected time to fixation of this recessive allele due to [[genetic drift]] alone ranged from about 1,100 years to about 100,000 years.<ref>{{cite journal |author1=Kawanishi, K. |author2=Sunquist, M. E. |author3=Eizirik, E. |author4=Lynam, A. J. |author5=Ngoprasert, D. |author6=Wan Shahruddin, W. N. |author7=Rayan, D. M. |author8=Sharma, D. S. K. |author9=Steinmetz, R. |year=2010 |title=Near fixation of melanism in leopards of the Malay Peninsula |journal=Journal of Zoology |volume=282 |issue=3 |pages=201–206 |doi=10.1111/j.1469-7998.2010.00731.x}}</ref>
Melanism in leopards has been hypothesized to be causally associated with a selective advantage for ambush.<ref>Majerus, M. E. N. (1998). ''Melanism: evolution in action.'' Oxford University Press, New York</ref> Other theories are that genes for melanism in felines may provide resistance to viral infections, or a high-altitude adaptation, since black fur absorbs more light for warmth.<ref>Seidensticker, J., Lumpkin, S. (2006). ''Smithsonian Q & A: the ultimate question and answer book. Cats''. Collins, New York</ref>

==In birds==
[[File:Poule Soie gris perle.jpg|thumb|White Silkie rooster|100x100px]]
[[File:Coq poule soie noir.png|thumb| Black Silkie rooster|100x100px]]
In April 2015, an extremely rare black [[flamingo]] was spotted on the Mediterranean island of [[Cyprus]].<ref>{{cite news|last=Krol|first=C.|date=2015 |title=Rare black flamingo spotted in Cyprus |work=The Telegraph|url=https://www.telegraph.co.uk/news/earth/wildlife/11526328/Rare-black-flamingo-spotted-in-Cyprus.html|url-status=dead|access-date=2015-05-16|archive-url=https://web.archive.org/web/20150425102520/http://www.telegraph.co.uk/news/earth/wildlife/11526328/Rare-black-flamingo-spotted-in-Cyprus.html|archive-date=2015-04-25}}</ref>

The chicken breeds [[Silkie]] and [[Ayam Cemani]] commonly exhibit this trait. Ayam Cemani is an uncommon and relatively modern breed of chicken from Indonesia. They have a dominant gene that causes hyperpigmentation (Fibromelanosis), making the chicken entirely black; including feathers, beak, and internal organs. Melanistic [[common pheasant]]s are sometimes intentionally released as game birds.{{cn|date=March 2025}}

Melanism in feral [[rock dove]]s is quite common, especially if the species is abundant in the area. The amount of pigmentation varies, from a slightly darker pigmentation in the pigeon’s wings, to being almost completely black.{{cn|date=March 2025}}

==In amphibians==
The [[alpine salamander]], ''Salamandra atra'', has one subspecies (''S. atra atra'') that is completely black.<ref>{{Cite web |title=Salamandre noire |url=http://www.karch.ch/karch/home/amphibien/amphibienarten-der-schweiz/alpensalamander.html |access-date=2022-11-30 |website=www.karch.ch}}</ref> The pigment comes from a specific cell called a melanophore, which produce the compound melanin.<ref>{{Cite journal |last1=Trevisan |first1=Pierluigi |last2=Pederzoli |first2=Aurora |last3=Barozzi |first3=Giancarlo |date=October 1991 |title=Pigmentary System of the Adult Alpine Salamander Salamandra atra atra (Laur., 1768) |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1600-0749.1991.tb00432.x |journal=Pigment Cell Research |language=en |volume=4 |issue=4 |pages=151–157 |doi=10.1111/j.1600-0749.1991.tb00432.x |pmid=1816547 |issn=0893-5785|url-access=subscription }}</ref><ref name=":5">{{Cite journal |last1=Pederzoli |first1=Aurora |last2=Trevisan |first2=Pierluigi |date=March 1990 |title=Pigmentary System of the Adult Alpine Salamander Salamandra atra aurorae (Trevisan, 1982) |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1600-0749.1990.tb00326.x |journal=Pigment Cell Research |language=en |volume=3 |issue=2 |pages=80–89 |doi=10.1111/j.1600-0749.1990.tb00326.x |pmid=2385569 |issn=0893-5785|url-access=subscription }}</ref>

There are four other subspecies of this salamander,<ref>{{Cite journal |last1=Helfer |first1=V. |last2=Broquet |first2=T. |last3=Fumagalli |first3=L. |date=2012-08-30 |title=Sex-specific estimates of dispersal show female philopatry and male dispersal in a promiscuous amphibian, the alpine salamander (''Salamandra atra'') |url=http://dx.doi.org/10.1111/j.1365-294x.2012.05742.x |journal=Molecular Ecology |volume=21 |issue=19 |pages=4706–4720 |doi=10.1111/j.1365-294x.2012.05742.x |pmid=22934886 |bibcode=2012MolEc..21.4706H |s2cid=22175429 |issn=0962-1083|url-access=subscription }}</ref> and they have varying levels of melanin pigmentation.<ref name=":5" /><ref name=":6" /><ref name=":4" /> The subspecies have yellow spots in different concentrations or proportions. The [[Chromatophore|pigment-producing cells]] that contribute to the yellow spots of some sub-species are called xanthophores.<ref name=":6">{{Cite journal |last1=Burgon |first1=James D. |last2=Vieites |first2=David R. |last3=Jacobs |first3=Arne |last4=Weidt |first4=Stefan K. |last5=Gunter |first5=Helen M. |last6=Steinfartz |first6=Sebastian |last7=Burgess |first7=Karl |last8=Mable |first8=Barbara K. |last9=Elmer |first9=Kathryn R. |date=April 2020 |title=Functional colour genes and signals of selection in colour-polymorphic salamanders |journal=Molecular Ecology |language=en |volume=29 |issue=7 |pages=1284–1299 |doi=10.1111/mec.15411 |pmid=32159878 |bibcode=2020MolEc..29.1284B |s2cid=212664862 |issn=0962-1083|doi-access=free |hdl=10261/234500 |hdl-access=free }}</ref> It appears that the fully-black phenotypes do not ever develop these xanthophores.<ref name=":4">{{Cite journal |last1=Bonato |first1=Lucio |last2=Steinfartz |first2=Sebastian |date=2005-01-01 |title=Evolution of the melanistic colour in the Alpine salamander Salamandra atra as revealed by a new subspecies from the Venetian Prealps |url=https://doi.org/10.1080/11250000509356680 |journal=Italian Journal of Zoology |volume=72 |issue=3 |pages=253–260 |doi=10.1080/11250000509356680 |s2cid=83504324 |issn=1125-0003|url-access=subscription }}</ref> Alpine salamanders produce a toxin from their skin, and both fully melanistic, black salamanders and spotted individuals produce the compound.<ref>{{Cite journal |last1=Beukema |first1=Wouter |last2=Speybroeck |first2=Jeroen |last3=Velo-Antón |first3=Guillermo |date=August 2016 |title=Salamandra |journal=Current Biology |volume=26 |issue=15 |pages=R696–R697 |doi=10.1016/j.cub.2016.03.045 |pmid=27505235 |s2cid=235611059 |issn=0960-9822|doi-access=free }}</ref>

Studies done that traced DNA histories have suggested that the original alpine salamander phenotype was black with some yellow spots, meaning that the fully black color evolved over time and was thus selected for over many generations.<ref name=":4" />

==In humans==
Melanism, meaning a mutation that results in completely dark skin, does not exist in humans. In humans, the amount of melanin is determined by three dominant alleles (AABBCC), and different ethnicities have varying amounts.<ref>{{cite journal |last1=Scheneider |first1=Patricia |title=the genetics and evolution of human color |journal=ProQuest |date=2004 |url=https://www.proquest.com/openview/ce7e635324be8a0c452ca71eec1e9419/1?pq-origsite=gscholar&cbl=49226}}</ref> Melanin is the primary determinant of the degree of skin pigmentation and protects the body from harmful [[ultraviolet radiation]]. The same ultraviolet radiation is essential for the synthesis of [[vitamin D]] in skin, so lighter colored skin – less melanin – is an adaptation related to the prehistoric movement of humans away from equatorial regions, as there is less exposure to sunlight at higher latitudes. People from [[Sub-Saharan Africa]], [[South Asia]], [[Southeast Asia]], Australia, and [[Melanesia]] may have very dark skin, but this is not melanism.
===Peutz–Jeghers syndrome===
{{Main|Peutz–Jeghers syndrome}}
This rare [[genetic disorder]] is characterized by the development of [[macules]] with [[hyperpigmentation]] on the lips and [[oral mucosa]] ([[melanosis]]), as well as benign polyps in the gastrointestinal tract.<ref>{{Cite journal|last=Broomfield|first=Denis|title=Mystery behind labial and oral melanotic macules: Clinical, dermoscopic and pathological aspects of Laugier-Hunziker syndrome|journal=World Journal of Clinical Cases|year=2018|volume=6|issue=10|pages=322–334|doi=10.12998/wjcc.v6.i10.322|pmid=30283795|pmc=6163135 |doi-access=free }}</ref>

==Socio-politics==
{{further|Melanin theory}}<!-- Image with inadequate rationale removed: [[File:NuwaubianBeginning.jpg|thumb|[[Nuwaubian]] Melanism]] -->
The term ''melanism'' has been used on [[Usenet]], [[internet forum]]s and [[blog]]s to mean an [[African Americans|African-American]] [[social movement]] holding that dark-skinned humans are the original people from which those of other [[human skin color|skin color]] originate. The term ''melanism'' has been used in this context as early as the mid-1990s<ref>{{cite web|url=http://way.net/dissonance/sundiata.html|title=Sundiata, AFROCENTRISM: THE ARGUMENT WE'RE REALLY HAVING.|access-date=2007-06-23}}</ref> and was promoted by some [[Afrocentrism|Afrocentrist]]s, such as [[Frances Cress Welsing]].

==See also==
* [[Albinism]]
** [[Tree Squirrel#Albino and white squirrels|Albino and white squirrels]]
* [[Amelanism]], lack of melanism
* [[Black squirrel]]
* [[Erythrism]], reddish pigmentation 
* [[Isabelline (colour)#In animals|Isabellinism]], lowered melanism 
* [[Heterochromia iridum]]
* [[Leucism]], a partial loss of pigmentation that results in animals with pale or white skin, hair and/or feathers
* [[Melanosis]], hyperpigmentation via increased melanin
** [[Ocular melanosis]]
* [[Peutz–Jeghers syndrome]], dark patches on the lips etc.
* [[Piebaldism]], patchy absence of melanin-producing cells 
* [[Vitiligo]], a skin condition which causes areas of the skin to lose its colour
* [[Xanthochromism]], an unusual yellow colouration in animals
* [[Zelandoperla fenestrata]], a stonefly exhibiting a [[Batesian mimicry]] melanic polymorphism

==References==
{{Reflist|2}}

==Bibliography==
{{Commons category|Melanism}}
* {{Cite video | people=[[David Attenborough]] |date=2002 | title=[[The Life of Mammals]] | medium=TV-Series and book | location=United Kingdom | publisher=BBC}}
* {{Cite book | first=Bernard | last=Kettlewell | year=1973 | title=The Evolution of Melanism | publisher=Clarendon Press | isbn=0-19-857370-7 | author-link=Bernard Kettlewell | title-link=The Evolution of Melanism }}
* {{Cite book | first=Michael | last=Majerus | year=1998 | title=Melanism: Evolution in Action | publisher=Oxford University Press | isbn=0-19-854982-2 | author-link=Mike Majerus | title-link=Melanism: Evolution in Action }}
* [https://www.doi.org/10.1046/j.1461-0248.2001.00279.x Melanism and disease resistance in insects]
* Fryer, G. 2013. How should the history of industrial melanism in moths be interpreted? ''The Linnean''. '''29''' (2): 15 - 22.

{{Pigmentation disorders}}
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[[Category:Genetic disorders with no OMIM]]
[[Category:Disturbances of pigmentation]]
[[Category:Dermatologic terminology]]
[[Category:Animal coat colors]]