Drosophila has four pairs of chromosomes: the sex chromosomes (XX in the females; XY in the males) and three pairs of autosomes. You are studying a new mutant strain with blue eyes. You wish to know if blue eye colour is a dominant mutation and on which chromosome the blue eye locus can be found. When you cross a pure-breeding female blue-eyed fly with vestigial wings and spineless bristles to a male fly with wild type eye colour, wings, and bristles, all of the F1 progeny are completely wild type. An F1 male is backcrossed to a triple mutant female, producing the following progeny (remember that there is no crossing over in Drosophila males):
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Wild type eyes, wings, and bristles: |
72 females, 69 males |
|
Wild type eyes and bristles, vestigial: |
83 females, 77 males |
|
Wild type wings, blue eyes, spineless: |
60 females, 65 males |
|
Blue eyes, spineless, vestigial: |
62 females, 58 males |
When an F1 female is backcrossed to a triple mutant male, the following 12,000 progeny are produced:
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Wild type eyes, wings, and bristles: |
90 females, 89 males |
|
Wild type eyes and bristles, vestigial: |
83 females, 98 males |
|
Wild type eyes and wings, spineless: |
37 females, 35 males |
|
Wild type wings and bristles, blue eyes: |
36 females, 34 males |
|
Wild type wings, blue eyes, spineless: |
92 females, 88 males |
|
Wild type eyes, spineless, vestigial: |
34 females, 39 males |
|
Wild type bristles, vestigial, blue eyes: |
33 females, 37 males |
|
Blue eyes, spineless, vestigial: |
90 females, 85 males |
Calculate the map distance between blue eye and any linked genes. Show your work.
