Explanation

Complete linkage. Linkage and Recombination Morgan carried out several dihybrid crosses in Drosophila to study genes that were sex linked. The crosses were similar to the dihybrid crosses carried out by Mendel in peas. He observed that when two genes were grouped on the same chromosome, same genes are highly linked of associated and show low recombination. When the genes are clearly present linked they show higher recombination. Morgan attributed this due to the physical association or linkage of the two genes and coined the term linkage to describe this physical association of genes on a chromosome and the term recombination to describe the generation of non-parental gene combinations. His student Alfred Sturtevant used the frequency of recombination between gene pairs on the same chromosome as a measure of the distance between genes and ‘mapped’ their position on the chromosome. Morgan hybridized yellow bodied and white eyed females with brown bodied and red eyed male (wild type) (cross-A) and inter-crossed their $F_{1}$-progeny [image:5c_image13.png] In the incomplete linkage we get some recombinant progeny but in complete linkage the recombinant progeny percentage is very less as compared to incomplete linkage