Imagine that you are working in a fruitfly ( Drosophila ) genetics laboratory. T
ID: 34161 • Letter: I
Question
Imagine that you are working in a fruitfly (Drosophila) genetics laboratory. Two new mutations have been recently discovered. Warty eyes (w) is recessive to normal eyes (W) at the warty locus. Hairy (h), the presence of extra sensory bristles, is recessive to normal (H). Assume that you have a pure breeding strain of each recessive phenotype (wwHH and WWhh) and a third strain that is pure breeding for both mutants (wwhh). Diagram the experimental design of crosses that you would use to test the null hypothesis that these two loci segregate independently; the alternative hypothesis is that they are linked. Design your crosses using the three strains described above. Make sure that you show exactly what experimental results you would use to test the null hypothesis of independent assortment. Please note: there is no recombination between loci on the same chromosome in male Drosophila because there are no crossovers (chiasmata) during meiosis in male Drosophila.
Explanation / Answer
Null hypothesis means, there is no linkage and no independent assortment of genes.
To test the independent assortment of genes we have to cross a parent (homozygous/heterozygous) with a double recessive parent.
So, lets cross wwHH X wwhh
offsprings would be wwHh. It just disapproves null hypothesis as independent assortment is happening.