What feature makes male and female Drosophila melanogaster easily distinguishable?

Step-by-step solution

Following this synthesis of ideas, experimental verification of the chromosomal theory of inheritance by Thomas Hunt Morgan and his colleagues, led to discovering the basis for the variation that sexual reproduction produced. Morgan worked with the tiny fruit flies, Drosophila melanogaster (Figure 4.10), which were found very suitable for such studies. They could be grown on a simple synthetic medium in the laboratory. They complete their life cycle in about two weeks, and a single mating could produce a large numb