Peppered moth

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Peppered moth
Biston betularia male.jpg
Male
Peppered moth (Biston betularia) female.jpg
Female
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Lepidoptera
Family: Geometridae
Genus: Biston
Species:
B. betularia
Binomial name
Biston betularia
Subspecies
  • B. b. alexandrina(Wehrli, 1941)
  • B. b. betularia
  • B. b. cognataria(Guenée, 1857)
  • B. b. contrasta(Barnes & Benjamin, 1923)
  • B. b. parva(Leech, 1897)
  • B. b. nepalensis(Inoue, 1982)
Synonyms
  • Phalaena (Geometra) betularia Linnaeus, 1758
  • Phalaena (Noctua) p-graecum(Poda, 1761)
  • marmoraria(Sepp, 1792)
  • Phalaena (Geometra) ulmaria(Borkhausen, 1794)
  • Eubyja betularia
  • Amphidasis huberaria(Ballion, 1866)
  • Amphidasys betularia var. doubledayaria(Millière, 1870)
  • Eurbyjodonta concinna(Warren, 1899)
  • Biston cognataria alexandrina(Wehrli, 1941)
  • Biston (Eubyjodonta) huberaria(tienschana Wehrli, 1941)
  • Biston cognataria sinitibetica(Wehrli, 1941)

The peppered moth (Biston betularia) is a temperate species of night-flying moth. [1] It is mostly found in the northern hemisphere in places like Asia, Europe and North America. Peppered moth evolution is an example of population genetics and natural selection. [2]

Contents

The caterpillars of the peppered moth not only mimic the form but also the colour of a twig. Recent research indicates that the caterpillars can sense the twig's colour with their skin and match their body colour to the background to protect themselves from predators. [3]

Description

The wingspan ranges from 45 mm to 62 mm (median 55 mm). It is relatively stout-bodied, with forewings relatively narrow-elongate. The wings are white, "peppered" with black, and with more-or-less distinct cross lines, also black. These transverse wing lines and "peppered" maculation (spotting) can also, in rare instances, be gray or brown; the spotting pattern, in particularly very rare cases, is sometimes a combination of brown and black/gray. [4] The black speckling varies in amount, in some examples it is almost absent, whilst in others it is so dense that the wings appear to be black sprinkled with white. The antennae of males are strongly bipectinate. [5] [6] Prout (1912–16) gives an account of the forms and congeners. [7]

Distribution

Biston betularia is found in China (Heilongjiang, Jilin, Inner Mongolia, Beijing, Hebei, Shanxi, Shandong, Henan, Shaanxi, Ningxia, Gansu, Qinghai, Xinjiang, Fujian, Sichuan, Yunnan, Tibet), Russia, Mongolia, Japan, North Korea, South Korea, Nepal, Kazakhstan, Kyrgyzstan, Turkmenistan, Georgia, Azerbaijan, Armenia, Europe and North America. [8]

Ecology and life cycle

Biston betularia caterpillars on birch (left) and willow (right), demonstrating twig mimicry and effective countershading. Biston betularia.png
Biston betularia caterpillars on birch (left) and willow (right), demonstrating twig mimicry and effective countershading.

In Great Britain and Ireland, the peppered moth is univoltine (i.e., it has one generation per year), whilst in south-eastern North America it is bivoltine (two generations per year). The lepidopteran life cycle consists of four stages: ova (eggs), several larval instars (caterpillars), pupae, which overwinter live in the soil, and imagines (adults). During the day, the moths typically rest on trees, where they are preyed on by birds.

The caterpillar is a twig mimic, varying in colour between green and brown. On a historical note, it was one of the first animals to be identified as being camouflaged with countershading to make it appear flat (shading being the main visual cue that makes things appear solid), in a paper by Edward Bagnall Poulton in 1887. [10] [11] Research indicates that the caterpillars can sense the twig's colour with their skin and match their body colour to the background to protect themselves from predators, an ability to camouflage themselves also found in cephalopods, chameleons and some fish, although this colour change is rather slower in the caterpillars. [3]

It goes into the soil late in the season, where it pupates in order to spend the winter. The imagines emerge from the pupae between late May and August, the males slightly before the females (this is common and expected from sexual selection). They emerge late in the day and dry their wings before flying that night.

The males fly every night of their lives in search of females, whereas the females only fly on the first night. Thereafter, the females release pheromones to attract males. Since the pheromone is carried by the wind, males tend to travel up the concentration gradient, i.e., toward the source. During flight, they are subject to predation by bats. The males guard the female from other males until she lays the eggs. The female lays about 2,000 pale-green ovoid eggs about 1 mm in length into crevices in bark with her ovipositor.

Resting behaviour

Figure 2a. Total number of observed moths = 59: Exposed trunk = 7; unexposed trunk = 7; trunk-branch joint = 23; branches = 22 Peppered moth resting positions 1964-2000.png
Figure 2a. Total number of observed moths = 59: Exposed trunk = 7; unexposed trunk = 7; trunk-branch joint = 23; branches = 22
Figure 2b. Total number of observed moths = 23: Exposed trunk =1; unexposed trunk =1; trunk branch join = 3; branches thicker than 5 centimetres diameter = 10; branches and twigs less thick than 5 centimetres = 8 Peppered moth resting positions 2001-2003.png
Figure 2b. Total number of observed moths = 23: Exposed trunk =1; unexposed trunk =1; trunk branch join = 3; branches thicker than 5 centimetres diameter = 10; branches and twigs less thick than 5 centimetres = 8

A mating pair or a lone individual will spend the day hiding from predators, particularly birds. In the case of the former, the male stays with the female to ensure paternity. Evidence for resting positions is given by data collected by the peppered moth researcher Michael Majerus, and it is given in the accompanying charts. These data were originally published in Howlett and Majerus (1987), and an updated version published in Majerus (1998), who concluded that the moths rest in the upper part of the trees. Majerus notes:

Creationist critics of the peppered moth have often pointed to a statement made by Clarke et al. (1985): "... In 25 years we have only found two betularia on the tree trunks or walls adjacent to our traps, and none elsewhere". The reason now seems obvious. Few people spend their time looking for moths up in the trees. That is where peppered moths rest by day.

From their original data, Howlett and Majerus (1987) concluded that peppered moths generally rest in unexposed positions, using three main types of site. Firstly, a few inches below a branch-trunk joint on a tree trunk where the moth is in shadow; secondly, on the underside of branches and thirdly on foliate twigs. The above data would appear to support this.

Further support for these resting positions is given from experiments watching captive moths taking up resting positions in both males (Mikkola, 1979; 1984) and females (Liebert and Brakefield, 1987).

Majerus, et al., (2000) have shown that peppered moths are cryptically camouflaged against their backgrounds when they rest in the boughs of trees. It is clear that in human visible wavelengths, typica are camouflaged against lichens and carbonaria against plain bark. However, birds are capable of seeing ultraviolet light that humans cannot see. Using an ultraviolet-sensitive video camera, Majerus et al. showed that typica reflect ultraviolet light in a speckled fashion and are camouflaged against crustose lichens common on branches, both in ultraviolet and human-visible wavelengths. However, typica are not as well camouflaged against foliose lichens common on tree trunks; though they are camouflaged in human wavelengths, in ultraviolet wavelengths, foliose lichens do not reflect ultraviolet light.

During an experiment in Cambridge over the seven years 2001–2007 Majerus noted the natural resting positions of peppered moths, and of the 135 moths examined over half were on tree branches, mostly on the lower half of the branch, 37% were on tree trunks, mostly on the north side, and only 12.6% were resting on or under twigs. [12] [13]

Polymorphism

Introduction on forms

There are several melanic and non-melanic morphs of the peppered moth. These are controlled genetically. A particular colour morph can be indicated in a standard way by following the species name in the form "morpha morph name". The use of "form" in the method of Biston betularia f. formname in detailing these variations is also a widespread practice.

These forms are often accidentally elevated to subspecies status when they appear in literature. Not adding the "f." (forma) or morpha implies that the taxon is a subspecies instead of a form, as in Biston betularia carbonaria instead of Biston betularia f. carbonaria. Rarely, forms have been elevated to species status, as in Biston carbonaria. Either of these two circumstances might lead to the erroneous belief that speciation was involved in the observed evolution of the peppered moth. This is not the case; individuals of each morph interbreed and produce fertile offspring with individuals of all other morphs; hence there is only one peppered moth species.

By contrast, different subspecies of the same species can theoretically interbreed with one another and will produce fully fertile and healthy offspring, but in practice do not, as they live in different regions or reproduce in different seasons. Full-fledged species are either unable to produce fertile and healthy offspring, or do not recognize each other's courtship signals, or both.

European breeding experiments have shown that in Biston betularia betularia, the allele for melanism producing morpha carbonaria is controlled by a single locus. The melanic allele is dominant to the non-melanic allele. This situation is, however, somewhat complicated by the presence of three other alleles that produce indistinguishable morphs of morpha medionigra. These are of intermediate dominance, but this is not complete (Majerus, 1998).

Form names

In continental Europe, there are three morphs: the white morph typica (syn. morpha/f. betularia), the dark melanistic morph carbonaria (syn. doubledayaria), and an intermediate form medionigra.

In Britain, the typical white morph is known as typica, the melanic morph is carbonaria, and the intermediate phenotype is named insularia.

In North America, the melanic black morph is morpha swettaria. In Biston betularia cognataria, the melanic allele (producing morpha swettaria) is similarly dominant to the non-melanic allele. There are also some intermediate morphs. In Japan, no melanic morphs have been recorded; they are all morpha typica.

Evolution

Biston betularia betularia morpha typica, the white-bodied peppered moth. Biston.betularia.7200.jpg
Biston betularia betularia morpha typica, the white-bodied peppered moth.
Biston betularia betularia morpha carbonaria, the black-bodied peppered moth. Biston.betularia.f.carbonaria.7209.jpg
Biston betularia betularia morpha carbonaria, the black-bodied peppered moth.

The evolution of the peppered moth over the last two hundred years has been studied in detail. At the start of this period, the vast majority of peppered moths had light coloured wing patterns which effectively camouflaged them against the light-coloured trees and lichens upon which they rested. However, due to widespread pollution during the Industrial Revolution in England, many of the lichens died out, and the trees which peppered moths rested on became blackened by soot, causing most of the light-coloured moths, or typica, to die off due to predation. At the same time, the dark-coloured, or melanic, moths, carbonaria, flourished because they could hide on the darkened trees. [14]

Since then, with improved environmental standards, light-coloured peppered moths have again become common, and the dramatic change in the peppered moth's population has remained a subject of much interest and study. This has led to the coining of the term "industrial melanism" to refer to the genetic darkening of species in response to pollutants. As a result of the relatively simple and easy-to-understand circumstances of the adaptation, the peppered moth has become a common example used in explaining or demonstrating natural selection to laypeople and classroom students through simulations. [15]

The first carbonaria morph was recorded by Edleston in Manchester in 1848, and over the subsequent years it increased in frequency. Predation experiments, particularly by Bernard Kettlewell, established that the agent of selection was birds who preyed on the carbonaria morph. Subsequent experiments and observations have supported the initial evolutionary explanation of the phenomenon. [16] [17] [18]

Genetic basis of melanism

The evolution of the industrial melanism mutation has been shown to be due to the insertion of a transposable element into the first intron of the cortex gene, resulting in an increase in the abundance of the cortex transcript, which is expressed in developing wings. [19]

Related Research Articles

<span class="mw-page-title-main">E. B. Ford</span> British ecological geneticist (1901–1988)

Edmund Brisco "Henry" Ford was a British ecological geneticist. He was a leader among those British biologists who investigated the role of natural selection in nature. As a schoolboy Ford became interested in lepidoptera, the group of insects which includes butterflies and moths. He went on to study the genetics of natural populations, and invented the field of ecological genetics. Ford was awarded the Royal Society's Darwin Medal in 1954. In the wider world his best known work is Butterflies (1945).

<span class="mw-page-title-main">Bernard Kettlewell</span> British lepidopterist (1907–1979)

Henry Bernard Davis Kettlewell was a British geneticist, lepidopterist and medical doctor, who performed research on the influence of industrial melanism on peppered moth coloration, showing why moths are darker in polluted areas. This experiment is cited as a classic demonstration of natural selection in action. After live video record of the experiment with Niko Tinbergen, Sewall Wright called the study as "the clearest case in which a conspicuous evolutionary process has actually been observed."

Michael Eugene Nicolas Majerus was a British geneticist and professor of evolution at the University of Cambridge. He was also a teaching fellow at Clare College, Cambridge. He was an enthusiast in Darwin's theory of evolution by natural selection and became a world authority in his field of insect evolutionary biology. He was widely noted for his work on moths and ladybirds and as an advocate of the science of evolution. He was also an enthusiastic educator and the author of several books on insects, evolution and sexual reproduction. He is best remembered as an ardent supporter and champion of experiments on peppered moth evolution.

<span class="mw-page-title-main">Geometer moth</span> Family of insects

The geometer moths are moths belonging to the family Geometridae of the insect order Lepidoptera, the moths and butterflies. Their scientific name derives from the Ancient Greek geo γεω, and metron μέτρον "measure" in reference to the way their larvae, or inchworms, appear to measure the earth as they move along in a looping fashion. A very large family, it has around 23,000 species of moths described, and over 1400 species from six subfamilies indigenous to North America alone. A well-known member is the peppered moth, Biston betularia, which has been subject of numerous studies in population genetics. Several other geometer moths are notorious pests.

<i>Of Moths and Men</i> 2002 book by Judith Hooper

Of Moths and Men is a book by journalist Judith Hooper about the Oxford University ecological genetics school led by E.B. Ford. The book specifically concerns Bernard Kettlewell's experiments on the peppered moth which were intended as experimental validation of evolution. She highlights supposed problems with the methodology of Kettlewell's experiments and suggests that these issues could invalidate the results obtained, ignoring or disparaging evidence supporting natural selection while repeatedly implying that Kettlewell and his colleagues committed fraud or made careless errors. Subject matter experts have described the book as presenting a "conspiracy theory" with "errors, misrepresentations, misinterpretations and falsehoods". The evolutionary biologist Michael Majerus spent the last 7 years of his life systematically repeating Kettlewell's experiments, demonstrating that Kettlewell had in fact been correct.

<span class="mw-page-title-main">Peppered moth evolution</span> Significance of the peppered moth in evolutionary biology

The evolution of the peppered moth is an evolutionary instance of directional colour change in the moth population as a consequence of air pollution during the Industrial Revolution. The frequency of dark-coloured moths increased at that time, an example of industrial melanism. Later, when pollution was reduced, the light-coloured form again predominated. Industrial melanism in the peppered moth was an early test of Charles Darwin's natural selection in action, and it remains a classic example in the teaching of evolution. In 1978, Sewall Wright described it as "the clearest case in which a conspicuous evolutionary process has actually been observed."

Bruce S. Grant is emeritus professor of biology at the College of William and Mary. He has a particular research interest in the peppered moth, He is a defender of the teaching of evolution and has criticized creationist Jonathan Wells, who has cited his work, as "dishonest."

The Evolution of Melanism: a study of recurring necessity; with special reference to industrial melanism in the Lepidoptera is a 1973 science book by the lepidopterist Bernard Kettlewell.

<span class="mw-page-title-main">Melanism</span> Congenital excess of melanin in an organism resulting in dark pigment

Melanism is the congenital excess of melanin in an organism resulting in dark pigment.

<span class="mw-page-title-main">J. W. Tutt</span> English schoolteacher and entomologist

James William Tutt was an English schoolteacher and entomologist. He was a founding editor of the journal Entomologists' Record from 1890 and published a landmark series on the British Lepidoptera in which he described numerous species of moths and was among the first to notice industrial melanism in the pepper moth Biston betularia and was among the first to provide a clear explanation of their increasing frequency based on the role of crypsis, natural selection by predators, and the effect of changed environmental conditions brought on by industrialism.

<span class="mw-page-title-main">Polyphenism</span> Type of polymorphism where different forms of an animal arise from a single genotype

A polyphenic trait is a trait for which multiple, discrete phenotypes can arise from a single genotype as a result of differing environmental conditions. It is therefore a special case of phenotypic plasticity.

Niche microdifferentiation is the process a species undergoes to reach genetic diversity within that species; it is the process by which an ecotype is created. This process is regulated by various environmental influences whether they be morphological, spatial, and/or temporal. This means that a trait of one organism in one area is not advantageous for the same species in a different location: "the trait that alters the environment in a manner that is favorable to growth tends to be reinforced and this positive feedback can further, to a certain extent, modify the selection pressure on itself". For example, a species of moth which is white and lives in an area where tree bark is stripped and tree color is white will more easily survive than a white moth in a different location where trees are moss-covered and green. This leads to adaptations that allow the species to exist in a slightly different environment. Organisms within the same species can undergo phenotypic and genotypic changes due to niche microdifferentiation. Conspecific organisms can vary in color, size, diet, behavior, and morphology due to differences in environmental pressures. Related topics include epigenetics, niche differentiation, and evolutionary biology.

<span class="mw-page-title-main">Industrial melanism</span> Evolutionary effect

Industrial melanism is an evolutionary effect prominent in several arthropods, where dark pigmentation (melanism) has evolved in an environment affected by industrial pollution, including sulphur dioxide gas and dark soot deposits. Sulphur dioxide kills lichens, leaving tree bark bare where in clean areas it is boldly patterned, while soot darkens bark and other surfaces. Darker pigmented individuals have a higher fitness in those areas as their camouflage matches the polluted background better; they are thus favoured by natural selection. This change, extensively studied by Bernard Kettlewell (1907–1979), is a popular teaching example in Darwinian evolution, providing evidence for natural selection. Kettlewell's results have been challenged by zoologists, creationists and the journalist Judith Hooper, but later researchers have upheld Kettlewell's findings.

<span class="mw-page-title-main">Kettlewell's experiment</span> Biological experiment on the peppered moth

Kettlewell's experiment was a biological experiment in the mid-1950s to study the evolutionary mechanism of industrial melanism in the peppered moth. It was executed by Bernard Kettlewell, working as a research fellow in the Department of Zoology, University of Oxford. He was investigating the cause of the appearance of dark-coloured moth since Industrial Revolution in England in the 19th century. He conducted his first experiment in 1953 in the polluted woodland of Birmingham, and his second experiment in 1955 in Birmingham as well as in the clean woods of Dorset.

Judith Hooper is an American journalist.

<i>Biston strataria</i> Species of moth

Biston strataria, the oak beauty, is a moth of the family Geometridae. It is native to Europe, the Balkan countries and the Black Sea region as far as Asia Minor and the Caucasus. The species was first described by Johann Siegfried Hufnagel in 1767. B. strataria is found in a variety of habitats, but is mostly found in woodlands where it rests on the bark of trees, camouflaged by its mottled black and grey wings. The male has feather-like antennae while those of the female are more thread-like. The moth has a wingspan of 40 to 56 mm.

Many types of polymorphism can be seen in the insect order Lepidoptera. Polymorphism is the appearance of forms or "morphs" differing in color and number of attributes within a single species. In Lepidoptera, polymorphism can be seen not only between individuals in a population but also between the sexes as sexual dimorphism, between geographically separated populations in geographical polymorphism and also between generations flying at different seasons of the year. It also includes the phenomenon of mimicry when mimetic morphs fly alongside non-mimetic morphs in a population of a particular species. Polymorphism occurs both at a specific level with heritable variation in the overall morphological design of individuals as well as in certain specific morphological or physiological traits within a species.

<span class="mw-page-title-main">Coloration evidence for natural selection</span> Early evidence for Darwinism from animal coloration

Animal coloration provided important early evidence for evolution by natural selection, at a time when little direct evidence was available. Three major functions of coloration were discovered in the second half of the 19th century, and subsequently used as evidence of selection: camouflage ; mimicry, both Batesian and Müllerian; and aposematism.

<i>Cleora scriptaria</i> Species of moth

Cleora scriptaria, the kawakawa looper moth, is a moth in the family Geometridae endemic to New Zealand.

References

  1. ↑ Grant, Bruce S. (1999). "Fine tuning the peppered moth paradigm: Reviewed Work: 'Melanism: Evolution in Action' by Michael E. N. Majerus". Evolution. 53 (3): 980–984. doi:10.2307/2640740. JSTOR   2640740.
  2. ↑ Gishlick, Alan (23 November 2006). "Icon 6 — Peppered Moths". National Center for Science Education . Retrieved 19 December 2009.
  3. 1 2 Eacock, A.; Rowland, H. R.; van’t Hof, A. E.; Yung, C.; Edmonds, N.; Saccheri, I. J. (August 2019). "Caterpillars of the peppered moth perceive color through their skin to match their body color to the background" . Retrieved 2 August 2019.
  4. ↑ "Photos of Peppered Moth (Biston betularia) · iNaturalist". iNaturalist. Retrieved 16 November 2020.
  5. ↑ Richard South, 1909 The Moths of the British Isles Frederick Warne
  6. ↑ Watson, L., and Dallwitz, M.J. 2003 onwards. British insects: the genera of Lepidoptera-Geometridae. Version: 29 December 2011
  7. ↑ Prout, L. B. (1912–16). Geometridae. In A. Seitz (ed.) The Macrolepidoptera of the World. The Palaearctic Geometridae, 4. 479 pp. Alfred Kernen, Stuttgart.pdf
  8. ↑ Jiang, N.; Xue, D.; Han, H. (2011). "A review of Biston Leach, 1815 (Lepidoptera, Geometridae, Ennominae) from China, with description of one new species". ZooKeys (139): 45–96. doi: 10.3897/zookeys.139.1308 . PMC   3260909 . PMID   22259309.
  9. ↑ Noor MA, Parnell RS, Grant BS (2008). Humphries S (ed.). "A Reversible Color Polyphenism in American Peppered Moth (Biston betularia cognataria) Caterpillars". PLOS ONE. 3 (9): e3142. Bibcode:2008PLoSO...3.3142N. doi: 10.1371/journal.pone.0003142 . PMC   2518955 . PMID   18769543.
  10. ↑ Poulton, Edward B. (October 1887). "Notes in 1886 upon Lepidopterous Larvae, etc". Transactions of the Entomological Society of London: 294.
  11. ↑ Thayer, Gerald H. (1909). Concealing-Coloration in the Animal Kingdom. Macmillan. pp.  22.
  12. ↑ Michael E. N. Majerus (August 2007). "The Peppered Moth: The Proof of Darwinian Evolution" (PDF). Archived from the original (PDF) on 15 June 2011. Retrieved 21 February 2011. powerpoint presentation as pdf {{cite web}}: External link in |quote= (help)
  13. ↑ Steve Connor, Science Editor (25 August 2007). "Moth study backs classic 'test case' for Darwin's theory". The Independent. Archived from the original on 7 October 2008. Retrieved 9 September 2007.{{cite news}}: |author= has generic name (help)
  14. ↑ Ken Miller (August 1999). "The peppered moth: an update". Brown University.
  15. ↑ "A modelling exercise for students using the peppered moth as its example" (PDF). Archived from the original (PDF) on 3 March 2016. Retrieved 27 April 2011.
  16. ↑ Mark Isaak (2 May 2005). "The peppered moth story". TalkOrigins Archive . Index to Creationist Claims: CB601.
  17. ↑ David Wilson (10 September 2003). "Dark moths increased in s. Britain after pollution control began". Index to Creationist Claims: CB601.2.3.
  18. ↑ David Wilson (10 September 2003). "In several areas dark moths were more common than expected". Index to Creationist Claims: CB601.2.2.
  19. ↑ Arjen E. van’t Hof, Pascal Campagne, Daniel J. Rigden, Carl J. Yung, Jessica Lingley, Michael A. Quail, Neil Hall, Alistair C. Darby & Ilik J. Saccheri (2016). "The industrial melanism mutation in British peppered moths is a transposable element". Nature . 534 (7605): 102–105. Bibcode:2016Natur.534..102H. doi:10.1038/nature17951. PMID   27251284.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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