I used to mark 'A' level biology essay papers for the University of London. The bloody peppered moth serially drove us examiners mad. It is not an example of evolution at all, though it is an example of natural selection at work. The dark moths were generated in small numbers well before the Industrial Revolution, but were not favoured by the environment and so few survived to breed. But a few did. The point is that the dark moths did not "evolve" as a result of soot blackening tree trunks. Dark moths were *always* there. In order for dark and light moths to evolve into two species, isolation of dark and light populations would have to occur for so long that, at the end of it all, the dark and light moths would no longer be able to interbreed. That bit is simply not part of the peppered moth story as we hear it. Now I'm not saying that the peppered moth can't evolve. I am saying that it can't evolve into two species unless isolation of populations takes place. God, I used to love scoring out bloody great long accounts of the peppered moth "as an example of evolution" with my red pen.