The answer is evolutionary change.
A mutation is the alteration of a nucleotide sequence in DNA. If a mutation occurs in the genes that control development it will cause great effects on the adult organism. Since these effects are so significant, they will make some evolutionary changes.For example, a mutation could cause parents with genes for bright coloration to get offspring with genes for darker coloration. After a period of time, that darker coloration will be more frequent in the population than before, so it will cause large-scale evolutionary change.