The dark secret of peppered moths in England is finally out. Their camouflage started changing during the Industrial Revolution due to the fact that soot pollution from early factories darkened the trees around the city.
According to a new study, this adaptation to the environment was driven by the same genes that created the brightly-colored wings of tropical species. Called cortex, this gene is suspected of being responsible for the colors on the wings of moths and butterflies.
That also applies to the changes seen in the peppered moth starting in the 19th century. While it is well known as an assistant in cell division, this segment of genetic code is now believed that it can also alter wing color.
“What’s exciting is that it turns out to be the same gene in both cases. For the moths, the dark coloration developed because they were trying to hide, but the butterflies use bright colors to advertise their toxicity to predators,” explained Chris Jiggins of the University of Cambridge.
However, one question arises: given the wide diversity of butterflies and moths, and the hundreds of genes working together to make a wing, why is the cortex always involved?
The wings of moths possess minuscule scales, displayed in alternating rows. Before mechanical manufacturing started developing and becoming widespread, peppered moths in England had a salt-and-pepper coloration on their wings, helping hem camouflage easily against the lightly-colored trees.
However, by 1819, air pollution – mainly in the form of dark soot – started to affect the lichen that lived on the trees, and also turned the trees into a darker color.
More than 17,000 different forms of butterflies have been discovered so far, as well as some 160,000 versions of moths. What’s fascinating is that each form of these Lepidoptera possesses unique wing patterns.
The fact that peppered moths in England became darker in color during the Industrial Revolution is not a discovery; the process even hasaname: industrial melanism.
What is new, however, is that this change was most likely driven by the same genes that are responsible for the vibrant colors of tropical Heliconus butterflies flying all throughout South America.