Consider the graphic of the moths. although not the peppered species, they are spotted and show variation in coloration. note the ancestral moth species. predict a situation where the ancestral species diverges into two additional species, now resulting in three, rather than one moth species in the area.

A factory nearby spreads ash all over the moths environment. Due to this predators are able to see the light colored moths which dwindles the number of light colored moths. In turn the dark moths survive because they blend in well with the color of the ash. The dark moths then breed with other dark moths which causes more variation in the dark colored moths and less of light colored moths