In genetics , complete linkage is defined as the state in which two loci are so close together that alleles of these loci are virtually never separated by crossing over . The closer the physical location of two genes on the DNA, the less likely they are to be separated by a crossing-over event. In the case of maleDrosophila there is complete absence of recombinant types due to absence of crossing over. This means that all of the genes that start out on a single chromosome, will end up on that same chromosome in their original configuration. In the absence of recombination, only parental phenotypes are expected.

Complete Linkage in Drosophila
Complete linkage is a type of genetic linkage where two genes are so close together on a chromosome that they are almost always inherited together. This means that the two genes are essentially inherited as a single unit, without any crossing over occurring between them.

Observation in Drosophila
A. Male Drosophila: In male Drosophila, complete linkage can be observed when two genes are located very close to each other on the same chromosome. As a result, during meiosis, the two genes are always inherited together without any recombination events taking place. This phenomenon can be useful in genetic studies to track the inheritance of specific traits.
B. Female Drosophila: In female Drosophila, complete linkage can also be observed when two genes are closely located on the same chromosome. However, due to the process of crossing over during meiosis, there is a possibility of recombination between the two genes, breaking the complete linkage.

Explanation
Complete linkage is a rare occurrence in nature, but it can be studied in Drosophila to understand how genes are inherited together. By analyzing the inheritance patterns of traits in Drosophila, researchers can gain insights into genetic linkage and recombination events.
In summary, complete linkage in Drosophila can be observed in both male and female individuals, but the presence of crossing over during meiosis in females can lead to the breaking of complete linkage between closely located genes.