• 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.
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