The change in allele frequencies from mostly light wings to dark wings has been commonly studied in evolution. It's a great example of natural selection favoring the more fit phenotype, in this case the dark that can blend in better with darker trees and darker, smoggy environment.
Why not competition: This doesn't have to do with limited resources.
Why not acquired: Lamarck's theory of acquired traits is defunct!! Don't fall for it!!
Why not overpopulation: This was not hinted at in the question.
RNA polymerase, a chemical in the cell, is answerable for making mRNA from the right quality. RNA polymerase is like DNA polymerase, yet it makes a RNA strand as opposed to a DNA strand. The promoter region of DNA Helix is attached by RNA polymerase.
It pulls in nucleotides that supplement those on the DNA strand containing the gene of interest. RNA polymerase duplicates one strand of DNA to make a stretching bit of singlestranded mRNA. RNA polymerase makes the mRNA strand in what is known as the 5' to 3' course.
