The peppered moth population changed over time because of the bad air quality in England. Which changed the color of the moths in the forests nearby. A scientist tested to see what was the cause and how the black colored moths survive in a clean forest and the actual peppered moths live in a dirty. the scientist found out that it was the factories that were the ones causing the pollution in the forests nearby. Scientist started to do experiments like the tests to see if black peppered moths would survive in a clean forest and a clean moth survive in a dirty forest. The results weren't to surprising because when they captured the moths that they marked there was fewer population of light moths in the dark forest than there were dark moths. The same with dark moths in a clean forest.
This showed that the dark moths were able to survive in the dark forest for they were dark to hide on the polluted trees to hide form predators. The same with the light moths they were able to survive in clean trees. This shows the theory of the scientist was right. The way to survive from predators you will have to adapt to the environment. This is called adaption also known as evolution when species change over time.