Genetic Analysis: Complementation tests Eye colour mutants were identified in a mutagenesis screen using Drosophila melanogaster. Six lines of white-eyed mutants were identified. Female flies from all six lines were bred with wild-type male flies. These mutants were also crossed with all the other white-eyed mutants in the same way. From the F1 generation male flies were scored for eye colour. The results from all reciprocal crosses are shown in the table below. Male flies Female flies Wild- type Line 1 Red Line 2 Red Line 3 Red Line 4 Line 5 Line 6 Wild- type Red Red Red Red Line 1 Red White Red Red Red Red Red Line 2 Red Red White Red White Red White Line 3 Red Red Red White Red White Red Line 4 Red Red White Red White Red White Line 5 Red Red Red White Red White Red Red Line 6 Red Red White Red White White a) Why were each of the mutant lines crossed to wild-type? To check that the mutations were recessive b) Why were reciprocal crosses carried out and why were only male flies scored? test for sex linkage - gene is not sex linked - if they were sex linked this would be revealed in the male which receives the X chromosome from the female parent c) How many complementation groups have been identified? 3 d) How many alleles have been identified in each complementation group? 2, 4, and 6 = three alleles, 3 and 5 = two alleles, 1 = 1 allele e) How many genes have been identified that contributing to eye colour? 3