Editing Peppered moth evolution (section)

=== Rise and fall of phenotype frequency ===

[[Melanism]] has been observed in both European and North American peppered moth populations. Information about the rise in frequency is scarce. Much more is known about the subsequent fall in [[phenotype]] frequency, as it has been measured by [[lepidopterist]]s using [[insect trap|moth traps]].

Steward compiled data for the first recordings of the peppered moth by locality, and deduced that the ''carbonaria'' morph was the result of a single [[mutation]] that subsequently spread. By 1895, it had reached a reported frequency of 98% in Manchester.<ref name="steward">{{cite journal |last=Steward |first=R. C. |year=1977 |title=Industrial and non-industrial melanism in the peppered moth ''Biston betularia'' (L.) |journal=Ecological Entomology |volume=2 |issue=3 |pages=231–243 |doi=10.1111/j.1365-2311.1977.tb00886.x |s2cid=85624115}}</ref>

From around 1962 to the present, the phenotype frequency of ''carbonaria'' has steadily fallen in line with cleaner air around industrial cities. Its decline has been measured more accurately than its rise, through more rigorous scientific studies. Notably, Kettlewell conducted a national survey in 1956, [[Bruce Grant (biologist)|Bruce Grant]] conducted a similar one in early 1996,<ref>{{cite web |last=Grant |first=Bruce |author-link=Bruce Grant (biologist) |title=Distribution of melanism in Britain |website=Talk Origins |url=https://www.talkorigins.org/faqs/wells/images/grantfile.jpg |access-date=2 June 2022}}</ref> and L.M. Cook in 2003.<ref name=cook2003>{{cite journal |last=Cook |first=L. M. |title=The rise and fall of the Carbonaria form of the peppered moth |journal=The Quarterly Review of Biology |year=2003 |volume=78 |issue=4 |pages=399–417 |pmid=14737825 |doi=10.1086/378925 |s2cid=26831926}}</ref>

Similar results were found in North America. Melanic forms have not been found in Japan. It is believed that this is because peppered moths in Japan do not inhabit industrialised regions.<ref name=cook2003/>