What causes future generations to be less adapted than their parental generations?

The initiating force of evolution is

$A$ mutation is most likely to have a selective advantage in evolution if:

Observations from England support evolution by natural selection. Before industrialization, $P$ moths were more abundant on trees, whereas after industrialization, $Q$ moths were more abundant. Identify $Q$.

Who stated that variations which are heritable and which make resource utilization better for few will enable only those to reproduce and leave more progeny?

You have studied the story of Peppered moths in England. Had the industries been removed, what impact would it have had on the moth population? Discuss.