Industrial Melanism


Industrial melanism refers to the evolution of dark body colours in animal species that live in habitats blackened by industrial soot. The phenomenon has been documented in numerous species that hide from predators by blending in with their backgrounds. Peppered moths provide one example. Before the industrial revolution, peppered moths in the UK were pale grey, but after their habitats became polluted with soot from coal‐fired industries, melanic (black) phenotypes became numerous and spread to other regions. Away from industrial centres, the pale phenotype remained common. Following clean air legislation a century later, the atmosphere improved, soot‐damaged habitats gradually recovered, and the pale phenotype returned as the predominant form. Parallel changes have occurred in America. The melanic and pale phenotypes are determined by genes, and the changes in their percentages in populations reflect natural selection. Experiments identify bird predation on the moth phenotypes as the agent of selection.

Key Concepts:

  • The natural colour patterns of animals are adaptations produced by natural selection.

  • A change in frequency (percentage) of genetically determined phenotypes in natural populations is direct evidence of evolutionary change.

  • Mutations introduce new genetic variation to a population, but recurrent mutations occur too rarely to bring about rapid changes in the frequency of genes.

  • Random changes in the frequency of genes (genetic drift) are irregular and unpredictable in direction.

  • Directional, rapid changes in the frequency of genetically determined phenotypes in populations result from natural selection.

  • Historical records on phenotypic frequencies from population samples allow the assessment of natural selection.

  • Gene flow (migration) retards genetic differentiation among geographically widespread populations.

  • Clines indicate different selection pressures along environmental gradients; when selection is removed, migration homogenises the differences along a cline.

  • Parallel evolution is ‘nature's replicate experiment’.

Keywords: bird predation; Biston betularia; camouflage; carbonaria; crypsis; natural selection; observable evolution; parallel evolution; peppered moths; polymorphism

Figure 1.

Polytypism and polymorphism in wing patterns of peppered moths. The side‐by‐side comparison illustrates the differences and similarities of British Biston betularia betularia (left column) and the American subspecies, B. betularia cognataria. At rest the wings span 4–5 cm. The American ‘typical’ phenotype (top right) is generally darker than the British typical (top left) and exhibits continuous lines marking the wings. The lines marking British typicals are variously interrupted producing a mottled or speckled pattern of white and black. The bottom pair illustrates fully melanic phenotypes of both subspecies. They are both virtually solid black and are indistinguishable from one another. Intermediates also occur in natural populations. The phenotypes result from multiple alleles at the same locus in both subspecies (Grant, ). Illustrations by Derek Whiteley, from Grant et al. cover. Reproduced by permission of the American Genetics Association.

Figure 2.

The decline in frequency of melanic Biston betularia at Caldy Common in West Kirby, UK, from 1959 to 2002. Average annual sample sizes were 437. Data from Clarke et al. , Grant and Clarke and 1999–2003 from S. Thompson (personal communication).

Figure 3.

A before‐and‐after comparison of the geographic distribution of melanic phenotypes of Biston betularia in Britain. The black segments of the pie charts represent the frequency of melanics at specific locations positioned on the maps, and the white segments represent the combined frequencies of typicals and ‘insularia’ (intermediates). The left map is abridged from the first national survey between 1952 and 1956 (summarised in Kettlewell, ). The locations selected from the early survey fall closest in position to the locations surveyed in 1996 graphed on the map to the right. Reproduced from Grant et al. , with permission from American Genetic Association.

Figure 4.

A comparison of melanic (carbonaria) frequencies in population samples across northern Britain extending from Abersoch, Wales, to Leeds, England. Liverpool and Manchester are included in the transect at 120 and 160 km, respectively. Early samples taken during the 1960s and 1970s are indicated by solid and open circles, respectively. Recent samples (squares) are from 2002. The dashed line describes the early, steep cline. The solid line is the theoretical prediction after 30 generations of selection against carbonaria (s=0.19) and maximum likelihood estimates of dispersal based on low levels of genetic differentiation among nine independent microsatellite loci along the melanic cline. Reproduced with permission from Saccheri et al. . Copyright, National Academy of Sciences, USA.

Figure 5.

The decline of melanism in American peppered moths, Biston betularia cognataria, in the northern states – Michigan (solid circles) and Pennsylvania (open circles) – and the relative absence of melanism in a southern state – Virginia (inverted triangles). Data from Grant and references in Grant and Wiseman .



Asami T and Grant BS (1995) Melanism has not evolved in Japanese Biston betularia (Geometridae). Journal of the Lepidopterists’ Society 49: 88–91.

Bishop JA (1972) An experimental study of the cline of industrial melanism in Biston betularia (L.) (Lepidoptera) between urban Liverpool and rural North Wales. Journal of Animal Ecology 41: 209–243.

Brakefield PM and Liebert TG (1990) The reliability of estimates of migration in the peppered moth Biston betularia and some implications for selection‐migration models. Biological Journal of the Linnean Society 39: 335–341.

Brakefield PM and Liebert TG (2000) Evolutionary dynamics of declining melanism in the peppered moth in the Netherlands. Proceedings of the Royal Society of London Series B 267: 1953–1957.

Clarke CA, Grant B, Clarke FMM and Asami T (1994) A long term assessment of Biston betularia (L.) in one UK locality (Caldy Common near West Kirby, Wirral) 1959–1993, and glimpses elsewhere. Linnean 10: 18–26.

Clarke CA, Mani GS and Wynne G (1985) Evolution in reverse: clean air and the peppered moth. Biological Journal of the Linnean Society 26: 189–199.

Clarke CA and Sheppard PA (1966) A local survey of the distribution of the industrial melanic forms of the moth Biston betularia and estimates of the selective values of these forms in an industrial environment. Proceedings of the Royal Society of London Series B 165: 424–439.

Cook LM (2000) Changing views on melanic moths. Biological Journal of the Linnean Society 69: 431–441.

Cook LM (2003) The rise and fall of the carbonaria form of the peppered moth. Quarterly Review of Biology 78: 399–417.

Cook LM and Grant BS (2000) Frequency of insularia during the decline in melanics in the peppered moth Biston betularia in Britain. Heredity 85: 580–585.

Cook LM, Grant BS, Saccheri IJ and Mallet J (2012) Selective bird predation on the peppered moth. The last experiment of Michael Majerus. Biology Letters, doi: 10.1098/rsbl.2011.1136 Available at (online 8 February 2012).

Cook LM and Turner JRG (2008) Decline of melanism in two British moths: spatial, temporal and interspecific variation. Heredity 101: 483–489.

Creed ER, Lees DR and Bulmer MG (1980) Pre‐adult viability differences of melanic Biston betularia (L.) (Lepidoptera). Biological Journal of the Linnean Society 13: 251–262.

Creed ER, Lees DR, Duckett JG et al. (1973) Biological method of estimating smoke and sulphur dioxide pollution. Nature 244: 278–280.

Cuthill IC, Partridge JC, Bennett ATD et al. (2000) Ultraviolet vision in birds. Advances in the Study of Behaviour 29: 159–214.

Douwes P, Mikkola K, Petersen B and Vestergren A (1976) Melanism in Biston betularius from north‐west Europe (Lepidoptera: Geometridae). Entomologica Scandinavia 7: 261–266.

Edleston RS (1864) Untitled. Entomologist 2: 150.

Endler JA (1986) Natural Selection in the Wild. Princeton: Princeton University Press.

Grant B and Howlett RJ (1988) Background selection by the peppered moth (Biston betularia Linn.): individual differences. Biological Journal of the Linnean Society 33: 217–232.

Grant BS (2004) Allelic melanism in American and British peppered moths. Journal of Heredity 95: 97–102.

Grant BS and Clarke CA (1999) An examination of intraseasonal variation in the incidence of melanism in peppered moths, Biston betularia (Geometridae). Journal of the Lepidopterists’ Society 53: 99–103.

Grant BS, Cook AD, Owen DF and Clarke CA (1998) Geographic and temporal variation in the incidence of melanism in peppered moth populations in America and Britain. Journal of Heredity 89: 465–471.

Grant BS, Owen DF and Clarke CA (1996) Parallel rise and fall of melanic peppered moths in America and Britain. Journal of Heredity 87: 351–357.

Grant BS and Wiseman LL (2002) Recent history of melanism in American peppered moths. Journal of Heredity 93: 86–90.

Haldane JBS (1924) A mathematical theory of natural and artificial selection. Transactions of the Cambridge Philosophical Society 23: 19–41.

Harrison JWH (1927) The induction of melanism in the Lepidoptera and its evolutionary significance. Nature 119: 127–129.

Hooper J (2002) Of Moths and Men: The Untold Story of Science and the Peppered Moth. New York: WW Norton.

Kettlewell B (1973) The Evolution of Melanism: The Study of Recurring Necessity. Oxford: Clarendon Press.

Kettlewell HBD (1955) Selection experiments on industrial melanism in the Lepidoptera. Heredity 9: 323–342.

Lees DR and Creed ER (1977) The genetics of the insularia forms of the peppered moth, Biston betularia. Heredity 39: 67–73.

Liebert TG and Brakefield PM (1987) Behavioural studies on the peppered moth Biston betularia and a discussion of the role of pollution and lichens in industrial melanism. Biological Journal of the Linnean Society 31: 129–150.

Majerus MEN (1998) Melanism: Evolution in Action. Oxford: Oxford University Press.

Majerus MEN (2008) Non‐morph specific predation on peppered moths (Biston betularia) by bats. Ecological Entomology 33: 679–683.

Majerus MEN, Brunton CFA and Stalker J (2000) A bird's eye view of the peppered moth. Journal of Evolutionary Biology 13: 155–159.

Mani GS (1982) A theoretical analysis of the morph frequency variation in the peppered moth over England and Wales. Biological Journal of the Linnean Society 17: 259–267.

Mikkola K (1984) On selective forces acting in the industrial melanism of Biston and Oligia moths (Lepidoptera: Geometridae and Noctuidae). Biological Journal of the Linnean Society 21: 409–421.

Mikkola K and Rantala MJ (2010) Immune defence, a possible nonvisual selective factor behind the industrial melanism of moths (Lepidoptera). Biological Journal of the Linnean Society 99: 831–838.

Noor MAF, Parnell RS and Grant BS (2008) A reversible color polyphenism in American peppered moth (Biston betularia cognataria) caterpillars. PLoS One 3(9): e3142., doi: 10.1371/journal.pone3.0003142.

Owen DF (1962) The evolution of melanism in six species of North American geometrid moths. Annals of the Entomological Society of America 55: 695–703.

Saccheri IJ, Rousett F, Watts PC, Brakefield PM and Cook LM (2008) Selection and gene flow on a diminishing cline of melanic peppered moths. Proceedings of the National Academy of Sciences of the USA 105: 16212–16217.

Sargent TD, Millar CD and Lambert DM (1998) The ‘classical’ explanation of industrial melanism. Evolutionary Biology 30: 299–322.

Skelhorn J, Rowland HM, Speed MP and Ruxton GD (2010) Masquerade: camouflage without crypsis. Science 327: 51.

Tutt JW (1896) British Moths. London: Routledge.

Van't Hof AE, Edmonds N, Dalikova M, Marec F and Saccheri IJ (2011) Industrial melanism in British peppered moths has singular and recent mutational origin. Science 332: 958–960.

Wells J (2000) Icons of Evolution: Science or Myth? Why Much of What we Teach about Evolution is Wrong. Washington DC: Regnery.

Young M and Musgrave I (2005) Moonshine: why the peppered moth remains an icon of evolution. Skeptical Inquirer 29: 23–28.

Further Reading

Berry RJ (1990) Industrial melanism and peppered moths (Biston betularia L.). Biological Journal of the Linnean Society 39: 301–322.

Cook LM, Dennis RHL and Mani GS (1999) Melanic morph frequency in the peppered moth in the Manchester area. Proceedings of the Royal Society of London Series B 266: 293–297.

Cook LM, Sutton SL and Crawford TJ (2005) Melanic moth frequencies in Yorkshire, an old English industrial hotspot. Journal of Heredity 96: 522–528.

Coyne JA (2001) Creationism by stealth. Nature 410: 745–746.

Coyne JA (2002) Evolution under pressure. Nature 418: 19–20.

Grant BS (2002) Sour grapes of wrath. Science 297: 940–941.

Lees DR (1981) Industrial melanism: genetic adaptation of animals to air pollution. In: Bishop JA and Cook LM (eds) Genetic Consequences of Man‐made Change, pp. 129–176. New York: Academic Press.

Mallet J (2004) The peppered moth: a black and white story after all. Genetics Society News 50: 34–38.

Rudge DW (2005) Did Kettlewell commit fraud? Re‐examining the evidence. Public Understanding of Science 14: 369–375.

Rudge DW (2010) Tut‐tut Tutt, not so fast. Did Kettlewell really test Tutt's explanation of industrial melanism. History and Philosophy of the Life Sciences 32: 493–520.

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How to Cite close
Grant, Bruce S(Jun 2012) Industrial Melanism. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0001788.pub3]