F1 Testcross Progeny Phenotype Number
narrow 603
fast, ziązag 609
ZIgzag 209
fast, narrow 201
fast 221
ZIgzag, narrow 237
fast, zigzag, narrow 7
wild type 5

Suppose a geneticist is using a three-point testcross to map three linked Drosophila recessive mutations called f, z, and n, where f is associated with abnormally fast movement; z is associated with zigzag movement pattern; and n is associated with narrow wings. The geneticist first crosses homozygous narrow flies to homozygous fast, zigzag flies. Next, she testcrosses the F1 progeny to fast, zigzag, narrow parents and obtains the following results. Based on these data, select the order of the three genes.