Editing Peppered moth evolution (section)

== Genetics ==

Tutt was the first to propose the "differential bird predation hypothesis" in 1896, as a mechanism of [[natural selection]]. The melanic morphs were better camouflaged against the bark of trees without foliose lichen, whereas the ''typica'' morphs were better camouflaged against trees with lichens. As a result, birds would find and eat those morphs that were not camouflaged with increased frequency.<ref name=swedentalk>{{cite web |title=The Peppered Moth: The Proof of Darwinian Evolution |last=Majerus |first=Michael E. N. |author-link=Michael Majerus |date=August 2007 |url=http://www.gen.cam.ac.uk/research/personal/majerus/SwedenPepperedmoth2007Ppt.pdf |access-date=2007-09-09 |url-status=dead |archive-url=https://web.archive.org/web/20110615081721/http://www.gen.cam.ac.uk/research/personal/majerus/SwedenPepperedmoth2007Ppt.pdf |archive-date=15 June 2011}}</ref>

In 1924, [[J.B.S. Haldane]] calculated, using a simple [[general selection model]], the selective advantage necessary for the recorded natural evolution of peppered moths, based on the assumption that in 1848 the frequency of dark-coloured moths was 2%, and by 1895 it was 95%. The dark-coloured, or melanic, form would have had to be 50% more fit than the typical, light-coloured form. Even taking into consideration possible errors in the model, this reasonably excluded the [[stochastic]] process of genetic drift, because the changes were too fast.<ref name="haldane">[[J. B. S. Haldane|Haldane, J.B.S.]] (1924). ''[[A Mathematical Theory of Natural and Artificial Selection]]''.</ref> Haldane's statistical analysis of selection for the melanic variant in peppered moths became a well known part of his effort to demonstrate that mathematical models that combined natural selection with Mendelian genetics could explain evolution – an effort that played a key role in the foundation of the discipline of [[population genetics]], and the beginnings of the [[modern synthesis (20th century)|modern synthesis]] of evolutionary theory with genetics.<ref>{{cite book |last=Bowler |first=Peter J. |author-link=Peter J. Bowler |title=Evolution: The history of an idea, 3rd edition |year=2003 |publisher=[[University of California Press]] |isbn=0-520-23693-9 |pages=[https://archive.org/details/evolutionhistory0000bowl_n7y8/page/331 331–332] |url=https://archive.org/details/evolutionhistory0000bowl_n7y8/page/331}}</ref>

The peppered moth ''Biston betularia'' is also a model of [[parallel evolution]] in the incidence of melanism in the British form (''f. carbonaria'') and the American form (''f. swettaria'') as they are indistinguishable in appearance. Genetic analysis indicates that both phenotypes are inherited as [[autosomal dominant]]s. Cross hybridizations indicate that the phenotypes are produced by alleles at a single locus.<ref name="Grant 2004">{{cite journal |last=Grant |first=B. S. |title=Allelic melanism in American and British peppered moths |journal=[[Journal of Heredity]] |year=2004 |volume=95 |issue=2 |pages=97–102 |pmid=15073224 |doi=10.1093/jhered/esh022 |doi-access=free}}</ref>

The gene for ''carbonaria'' in ''B. betularia'' was thought to be in a region of [[chromosome]] 17. It was later concluded that the gene could not be in that region, because none of the genes in the chromosome coded for either wing pattern or melanisation. The region that was used to find it was the first intron of the orthologue of the ''cortex'' gene in ''Drosophila''. Through elimination of candidates within the region based on rarity, a 21,925 base pair insert remained. The insert, labelled ''carb''-TE, is a class II [[transposable element]] that has an approximately 9-kb non-repetitive sequence tandemly repeated two and one third times. There are 6 base pairs of inverted repeats and duplicated 4 base pairs at the target site not present in ''typica'' moths. ''Carb-''TE has higher expression during the stage of rapid wing disc morphogenesis. The mechanism of how the gene increases expression, and whether it is the only gene involved, is still not known.<ref name="van't Hof Edmonds 2011">{{cite journal |last1=van't Hof |first1=Arjen E. |last2=Edmonds |first2=Nicola |last3=Dalikova |first3=Martina |last4=Marec |first4=Frantisek |last5=Saccheri |first5=Ilik J. |title=Industrial Melanism in British Peppered Moths Has a Singular and Recent Mutational Origin |date=20 May 2011 |journal=[[Science (journal)|Science]] |volume=332 |issue=6032 |pages=958–960  |bibcode=2011Sci...332..958V |pmid=21493823 |doi=10.1126/science.1203043 |s2cid=24400858}}</ref><ref name="van't Hof Campagne 2016">{{cite journal |last1=van't Hof |first1=Arjen E. |last2=Campagne |first2=Pascal |last3=Rigden |first3=Daniel J. |last4=Yung |first4=Carl J. |last5=Lingley |first5=Jessica |last6=Quail |first6=Michael A. |last7=Hall |first7=Neil |last8=Darby |first8=Alistair |last9=Saccheri |first9=Ilik J. |title=The industrial melanism mutation in British peppered moths is a transposable element |date=2 June 2016 |journal=[[Nature (journal)|Nature]] |volume=534 |issue=7605 |pages=102–117 |bibcode=2016Natur.534..102H |pmid=27251284 |doi=10.1038/nature17951 |s2cid=3989607}}</ref>