Peppered moths come in two colors, black and white. what did kettlewell show, with regard to peppered moth populations and tree coloring? (recall that england at the time was heated mainly by coal in urban areas.)

Peppered moth color variation is a good example of natural selection. In natural selection, genotype variations that will increase the chance of survival and reproduction of some organism are preserved and will be inherited.During the Industrial revolution, due to pollution, trees become darker in the urban area. Light-colored moths were, thus, easy prey. The dark-colored moths were able to camouflage on dark trees and avoid predators. The phenomenon is known as industrial melanism. So, in polluted urban areas, the number of dark-colored peppered moths increased. In the clean environment, were much effective in hiding from predators and they outnumbered the dark-colored moths. 

That would be a working theory.