Question

Write the scientific name of the organism Thomas Hunt Morgan and his colleagues worked with for their experiments. Explain the correlation between linkage and recombination with respect to genes as studied by them.

Answer 1

Thomas Hunt Morgan and his colleagues used fruitfly, or Drosophila melanogaster to study linkage

Morgan had carried out various experiments involving dihybrid crosses in Drosophila to study the sex-linked genes. In one such experiment, he crossed yellow-bodied, white-eyed flies with brown-bodied, red-eyed ones. The resultant F₂ ratio deviated from the Mendelian dihybrid ratio of 9:3:3:1. Morgan suggested that this was because of the phenomenon of linkage. He found that the genes for both the characters were present on the X chromosome. When two genes are located close to each other on the same chromosome, then the chances of formation of new recombinations are very less. This is because of physical associations of genes present on the same chromosome. Morgan named this phenomenon as 'linkage'. Thus it can be stated that higher the linkage between two genes, lesser are the chances of recombination.