{{Short description|Congenital excess of melanin in an organism resulting in dark pigment}} [[File:Eastern gray squirrel melanistic (61011).jpg|thumb|Melanistic black eastern grey squirrel (''Sciurus carolinensis'')]] [[File:Cavia porcellus-Licorice.jpg|thumb|Melanistic guinea pigs (''Cavia porcellus'') are rare, and are used in rituals by Andean ''curanderos''.<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 congenital excess of melanin in an organism resulting in dark 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 tumors, 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 melanism. Most commonly, dark individuals become 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 heritable: A 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 |date=2024 |volume=386 |issue=6720|pages=453–458 |doi=10.1126/science.ado5331 |pmid=39446930 |bibcode=2024Sci...386..453N }}</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 |date=2023 |volume=32 |issue=18 |pages=4986–4998 |doi=10.1111/mec.17085|pmid=37503654 |bibcode=2023MolEc..32.4986F |doi-access=free }}</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 evolutionary 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 camouflaged 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}} thumb|Melanistic and normally coloured jaguars In 1938 and 1940, two melanistic bobcats 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, resulting in blotchy, irregular spotting]] In 2003, the dominant mode of inheritance of melanism in jaguars was confirmed by performing phenotype-transmission analysis in a 116-individual captive 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 cats. 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 |bibcode=2003CBio...13..448E |s2cid=19021807 |doi-access=free }}</ref>
Melanism in leopards is inherited as a Mendelian, 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 leopards 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== thumb|White Silkie rooster|100x100px 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 pheasants are intentionally bred and released as game birds.<ref>{{cite web |last1=Cottrell |first1=Vicki |title=Phasianus colchicus (common pheasant) |date=2015 |url=https://www.cabidigitallibrary.org/doi/10.1079/cabicompendium.70470 |publisher=CABI Compendium |doi=10.1079/cabicompendium.70470 |access-date=2025-08-19}}</ref>
Melanism in feral rock doves 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.{{citation needed|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 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 |bibcode=2016CBio...26.R696B |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>
===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 forums and blogs to mean an African-American social movement holding that dark-skinned humans are the original people from which those of other 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 Afrocentrists, such as Frances Cress Welsing.
==See also== * Albinism ** Albino and white squirrels * Amelanism, lack of melanism * Black squirrel * Erythrism, reddish pigmentation * 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== <ref>Searle, A. G. (1968) ''Comparative Genetics of Coat Colour in Mammals''. Logos Press, London</ref><ref>{{cite book |author=Begon, M. |url=https://books.google.com/books?id=Lsf1lkYKoHEC&pg=PA9 |title=Ecology: From individuals to ecosystems |author2=Townsend, C. R. |author3=Harper, J. L. |publisher=Wiley Publishing |year=2006 |isbn=9781405151986 |edition=Fourth |location=Malden, Oxford |name-list-style=amp}}</ref>{{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.
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Category:Genetic disorders with no OMIM Category:Disturbances of pigmentation Category:Dermatologic terminology Category:Animal coat colors