In Drosophila melanogaster the allele for long wings is dominant over the allele for vestigial wings, and the allele for a grey body is dominant over the allele for a black body. A testcross was done to check for genetic linkage between the genes for these traits, with the following results for the offspring: 410 flies with long wings and a black body
105 flies with long wings and a grey body
390 flies with vestigial wings and a grey body
95 flies with vestigial wings and a black body
Which of the following best represents the map distance between the genes for these two traits?

Question

Quizplus · Accepted Answer

The map distance is calculated using the formula: (Number of recombinant offspring / Total number of offspring) x 100. Recombinant offspring are those with long wings and grey body (105) and vestigial wings and black body (95), totaling 200. The total number of offspring is 1000. Thus, the map distance is (200/1000) x 100 = 20.0 map units.

In Drosophila Melanogaster the Allele for Long Wings Is Dominant