Answer:
natural selection
Step-by-step explanation:
According to the evolutionary theory, natural selection can be understood as the process of differential survival and reproduction of individuals due to phenotypic differences, which may be associated with different colors, sizes, behaviors, etc. The only prerequisite is that these phenotypic differential traits must be heritable, which means that they must be passed by genes from one generation to the next. For example, in the white-throated sparrow, it has been discovered two morphs that differ in behavior due to a chromosomal inversion in sex chromosomes.