Industrial melanism is an evolutionary effect where dark pigmentation (melanism) evolves in a species living in a polluted industrial environment
. Industrial byproducts, such as soot and other waste, darken the environment, and some animals adapt by evolving darker coloration via increased melanin production
. The process of industrial melanism is a straightforward example of natural selection
:
- Pollution darkens the environment
- Animals with darker pigmentation have better camouflage, increasing their fitness and reducing their risk of predation
- Darker individuals breed and become more common over time
Industrial melanism is most studied in moths, such as the peppered moth (Biston betularia)
. The light-colored peppered moth uses its speckled wings to camouflage against lichens on tree bark
. However, in industrialized areas, pollution killed the lichens and covered trees in soot, making the light-colored moths more visible to predators
. Darker moths had a higher survival rate, and the once rare melanic form of the peppered moth became more common
. As pollution decreased due to modern environmental technologies, the selection pressure from predation reversed, and the light-colored moth became more common again
. Industrial melanism has also been observed in other species, such as the two-spot ladybird beetle and seasnakes
. In the seasnake (Emydocephalus annulatus), melanism helps the animal excrete trace elements through its skin, which binds to the melanin pigments
