In a dihybrid cross white eyed, yellow bodied female Drosophila crossed with red eyed, brown bodied male Drosophila produced in F2 generation 1.3 percent recombinants and 98.7 percent progeny with parental type combinations. This observation of Morgan deviated from Mendelian F2 phenotypic dihybrid ratio. Explain, giving reasons, Morgan’s observations.

• According to Mendel, the F2 phenotypic dihybrid ratio is 9:3:3:1.

• The ratios of Morgan’s dihybrid cross between white eyed, yellow bodied female Drosophila and red eyed, brown bodied male Drosophila was significantly different. It produced 1.3% recombinants and 98.7% progeny with parental type combinations.

• Morgan and his group knew that the genes were located on the X chromosome. Hence, they observed that when two genes in a dihybrid cross are located on the same chromosome, the proportion of parental gene is much higher than the non-parental gene.

• He also coined the terms linkage (the physical association of genes on a chromosome) and recombination(when crossing over of genes occurs). When linkage is very tight, recombination is lower and when linkage is very loose, recombination is higher.