In england, peppered moths have two color forms, light and dark. dark is a dominant trait. until about 1850, the majority of
moths in england were light colored. with the beginning of the industrial revolution in the late 1800's, the moth population
began to change color. the majority of the moths were dark by the 1920's. how can this be explained genetically?

Theory of natural selection by Charles Darwin explains the moth appearance in England. The theory of genetics describes this as a mere shift of trait due to environmental factors.

Peppered moths are the moths found in England from a long time ago. The environment before the industrial revolution was pure and pollution free, which led to the growth of the white variety of moths as they were able to camouflage better with the bark of the trees from their hunters. The white trait were the parents, and fertilization between the two recessive traits gave rise to the recessive traits only.

But with the industrial revolution, the pollution increased to a huge extent, leading to deposition of smokes and soot on trees bark where white variety of the white moths got easily recognizable. This led to the black moths which now can camouflage better. Thus the nature selected black variety over white variety for better survival, and the white variety reduced dramatically.

well the answer is 2!