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Famous peppered moth's dark secret is out

Scientists have finally revealed the specific mutation which turned moths black during the Industrial Revolution.

Famous peppered moth's dark secret is out

In a significant evolutionary case study, a black form of the peppered moth rapidly took over in industrial parts of the UK during the 1800s, as the tree trunks and walls of the habitat of the moths were turned black due to soot.

Now, a team of researchers from University of Liverpool have managed to reveal the genetic change that caused this adaptation. The researchers also also calculated the most likely date for the mutation - 1819.

The findings of the study were published in the journal Nature, alongside a second paper, in which the researchers went on to describe how the same gene allows tropical butterflies to change their colour schemes.

Dr Ilik Saccheri said that he has been working on the peppered moth since setting up his Liverpool laboratory 15 years ago. "When I started working on it I was surprised, given how well known it is, that no-one had actually tried to... characterise the underlying genetics controlling the physical appearance of this moth," he said.

"It's a graphic example of rapid evolutionary change. In the days before we could track mutation and change in bacteria and viruses, there weren't many examples of visible change within a human lifetime," he added.

Black moths are completely different from the insect's usual mottled white and they were first spotted in 1848 - 10 years before Darwin and Wallace formally outlined the concept of natural selection.

"Unfortunately, there weren't people recording the rise in frequency in the latter part of the 1800s. But the next record, which is around 1900 in the Manchester region, indicates that it's almost completely replaced the light-coloured form," said Dr Saccheri. "The typical form didn't go extinct; it just went to very low frequencies in cities. But it still remained as the common form in the countryside."