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.[2]
The morbid deposition of black matter, often of a malignant character causing pigmentedtumors, is calledmelanosis.[3]
A melanisticEuropean adder (Vipera berus) compared to a normal-colored adder
Melanism related to the process ofadaptation is called adaptive melanism. Most commonly, dark individuals becomefitter to survive and reproduce in their environment as they are better camouflaged. This makes some species less conspicuous to predators, while others, such asleopards, use it as a foraging advantage during night hunting.[4] Typically, adaptive melanism isheritable: Adominantallele, which is entirely or nearly entirely expressed in thephenotype, is responsible for the excessive amount of melanin. By contrast, adaptive melanism associated with Batesian mimicry inZelandoperla fenestratastoneflies is controlled by arecessive allele at the ebony locus.[5][6]
Industrial melanism is anevolutionary effect in insects such as the peppered moth,Biston betularia in areas subject toindustrial pollution. Darker pigmented individuals are favored bynatural selection, apparently because they are bettercamouflaged against polluted backgrounds. When pollution was later reduced, lighter forms regained the advantage and melanism became less frequent.[7][8][9][10][11][12] Other explanations have been proposed, such as that the melanin pigment enhances function of immune defences,[13] or a thermal advantage from the darker coloration.[14][15][16]
In 1938 and 1940, two melanisticbobcats were trapped alive in sub-tropicalFlorida.[17]
Pseudomelanism on acheetah, resulting in blotchy, irregular spotting
In 2003, thedominant mode of inheritance of melanism in jaguars was confirmed by performingphenotype-transmission analysis in a 116-individual captivepedigree. Melanistic animals were found to carry at least one copy of a mutantMC1R sequenceallele, bearing a 15-base pair inframe deletion. Ten unrelated melanistic jaguars were eitherhomozygous orheterozygous for this allele. A 24-base pair deletion causes the incompletely dominant allele for melanism in the jaguarundi. Sequencing of theagouti signalling peptide in theagouti gene coding region revealed a 2-base pair deletion in blackdomestic cats. These variants were absent in melanistic individuals ofGeoffroy's cat,oncilla,pampas cat andAsian golden cat, suggesting that melanism arose independently at least four times in the cat family.[18]
Melanism in leopards is inherited as aMendelian,monogenicrecessive trait relative to the spotted form. Pairings of black animals have a significantly smaller litter size than other possible pairings.[19] Between January 1996 and March 2009,Indochinese leopards were photographed at 16 sites in theMalay Peninsula in a sampling effort of more than 1000 trap nights. Of 445 photographs of melanistic leopards, 410 were taken south of theKra 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 togenetic drift alone ranged from about 1,100 years to about 100,000 years.[20] Melanism in leopards has been hypothesized to be causally associated with a selective advantage for ambush.[21] 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.[22]
In April 2015, an extremely rare blackflamingo was spotted on the Mediterranean island ofCyprus.[23]
The chicken breedsSilkie andAyam 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. Melanisticcommon pheasants are intentionally bred and released as game birds.[24]
Melanism in feralrock 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]
Thealpine salamander,Salamandra atra, has one subspecies (S. atra atra) that is completely black.[25] The pigment comes from a specific cell called a melanophore, which produce the compound melanin.[26][27]
There are four other subspecies of this salamander,[28] and they have varying levels of melanin pigmentation.[27][29][30] The subspecies have yellow spots in different concentrations or proportions. Thepigment-producing cells that contribute to the yellow spots of some sub-species are called xanthophores.[29] It appears that the fully-black phenotypes do not ever develop these xanthophores.[30] Alpine salamanders produce a toxin from their skin, and both fully melanistic, black salamanders and spotted individuals produce the compound.[31]
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.[30]
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.[32]
^Morales, E. (1995).The Guinea Pig : Healing, Food, and Ritual in the Andes. University of Arizona Press.ISBN0-8165-1558-1.
^Osinga, N.; Hart, P.; van VoorstVaader, P. C. (2010). "Albinistic common seals (Phoca vitulina) and melanistic grey seals (Halichoerus grypus) rehabilitated in the Netherlands".Animal Biology.60 (3): 273−281.doi:10.1163/157075610x516493.S2CID84554567.
^Webster's Revised Unabridged Dictionary (1913).MelanosisArchived 2013-07-29 at theWayback Machine. C. & G. Merriam Co. Springfield, Massachusetts. Page 910
^King, R.C., Stansfield, W.D., Mulligan, P.K. (2006).A Dictionary of Genetics, 7th ed., Oxford University Press
^abNi, Steven; McCulloch, Graham; Kroos, Gracie; King, Tania; Dutoit, Ludovic; Foster, Brodie; Hema, Kahu; Jandt, Jennifer; Peng, Mei; Dearden, Peter; Waters, Jonathan (2024). "Human-driven evolution of color in a stonefly mimic".Science.386 (6720):453–458.Bibcode:2024Sci...386..453N.doi:10.1126/science.ado5331.PMID39446930.
^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.
^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.
^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
^Grant, B. S., Wiseman L. L., 2002. Recent history of melanism in American peppered moths. Journal of Heredity 93:86-90.
^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.
^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.
^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.
^Mikkola, K., Albrecht, A., 1988. The melanism ofAdalia-bipunctata around the Gulf of Finland as an industrial phenomenon (Coleoptera, Coccinellidae). Annales Zoologici Fennici 25:177–85.
^Muggleton, J., Lonsdale, D., Benham, B. R., 1975. Melanism inAdalia-bipunctata L (ColCoccinellidae) and its relationship to atmospheric pollution. Journal of Applied Ecology 2:451–464.
^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.
^Ulmer, F. A. (1941)Melanism in the Felidae, with special reference to the Genus Lynx. Journal of Mammalogy 22 (3): 285–288.
^Kawanishi, K.; Sunquist, M. E.; Eizirik, E.; Lynam, A. J.; Ngoprasert, D.; Wan Shahruddin, W. N.; Rayan, D. M.; Sharma, D. S. K.; Steinmetz, R. (2010). "Near fixation of melanism in leopards of the Malay Peninsula".Journal of Zoology.282 (3):201–206.doi:10.1111/j.1469-7998.2010.00731.x.
^Majerus, M. E. N. (1998).Melanism: evolution in action. Oxford University Press, New York
^Seidensticker, J., Lumpkin, S. (2006).Smithsonian Q & A: the ultimate question and answer book. Cats. Collins, New York
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