Morgan’s Concept of Linkage

Morgan’s Concept of Linkage:

Morgan (1910) while working on Drosophila, stated that coupling and repulsion are two aspects of the same phenomenon, which he described as ‘linkage‘. He defined linkage as The tendency of the genes, that are present in the same chromosome, to remain in their original combination and to enter together in the same gamete.

He conducted an experiment on heredity in Drosophila melanogaster and introduced the concept of sex-linked inheritance. He also developed the method of mapping gene positions on chromosomes and the preparation of chromosome maps. Morgan established the Gene concept and received Nobel Prize in 1933.

Chromosome Theory of Linkage:

Morgan and Castle formulated ‘The Chromosome Theory of Linkage‘. It has the following characteristics:

1. Genes that show linkage are situated in the same chromosome.

2. Genes are arranged in a linear fashion in the chromosome, linkage of genes is linear.

3. The distance between the linked genes is inversely propositional to the strength of linkage. The genes which are closely located show strong linkage, whereas those, which are widely separated have more chances to get separated by crossing over.

4. Linked genes remain in their original combination during the course of inheritance.