Question

Linkage in Drosophila was first discovered by-
A.Bridges
B.Mendel
C.Bateson and Punnett
D.Morgan

Answer 1

Hint:The close association of gene in material or on the same chromosome is referred to as linkage. Linkage is especially seen in the genes that are closely present, particularly on the same chromosome. The term linkage was given by Morgan. Linkage was ‘very first’ discovered by Bateson and Punnett in Lathyrus odoratus with respect to flower color and pollen shape.

Complete step by step answer:There are four linkage groups (4 pairs of chromosomes) present in Fruit-fly, Drosophila melanogaster. Thomas Hunt Morgan was the first person to discover linkage in Drosophila. Morgan went through several dihybrid crosses in Drosophila for the study of sex-linked genes. In his experiment, the study was made between yellow-bodied, white-eyed females to brown-bodied, red-eyed males and then their F1 progenies were also intercrossed.
Since it was clear to Morgan and his allies that the genes were present on the X-chromosome so they saw that when the two genes are studied after a dihybrid cross on the same chromosome, the proportion of parental gene combinations were much higher than the non-parental ones. And thus, Morgan gave the term linkage for this association.
Mendel is known as the Father of genetics, he experimented on garden peas and gave two general rules based on his studies on the monohybrid cross.
Bridges also studies the chromosome and heredity along with Morgan and his student Alfred Sturtevant and taught about recombination.
Thus, the correct option here is option D, Morgan.

Note: Complete linkage is an example of dependent assortment while incomplete linkage implies to normal Mendelian cross. While making his study on Drosophila, Morgan saw that the two genes had not segregated independently of one another, the F2 ratio deviated from the general 9:3:3:1 ratio (this ratio is expected when two genes are independent).
Also, the genes which are very tightly packed on the same chromosome are said to show a very low rate of recombination while those which are loosely linked show a high degree of recombination.