In a population of fruit flies grown in laboratory conditions, a new phenotype arises. Instead of the typical red eyes, a purple-eyed individual is seen. This individual survives to adulthood and is able to mate with other flies. Two students studying the fruit fly population discuss the origin of the purple-eyed fruit fly. One student insists that the fly came from outside of the original fruit fly population. The other student claims that the fly originated from within the laboratory fruit fly population. Which statements defend the claim of student two that the new phenotype originated from within the fruit fly population?