O. In fruit flies, three genes on the second chromosome (an autosome) affect eye
color, bristle number and wing shape. The recessive traits are cinnabar eyes
(allele r), reduced bristle number (allele n) and vestigial wings (allele v). The
corresponding dominant traits are red eyes (allele R), full bristle number
(allele N) and long wings (allele V). A female true breeding for cinnabar eyes,
reduced bristle number and vestigial wings was mated to a male true
breeding for red eyes, full bristle number and long wings. F1 females, with red
eyes, full bristle number and long wings, were mated to males with cinnabar
eyes, reduced bristle number and vestigial wings. The resulting F2 offspring
are listed below.
Parentals
n_ r_ v
N
R
V
v
N
R
V
n _ r_ v
n
r
v
n
r
v
X
n
F1 female
r
X
N R V
Eye color
(middle)
Bristle
Number
Wing
shape
Cinnabar
Red
Cinnabar
Red
Cinnabar
Red
Cinnabar
Red
Reduced
Full
Reduced
Full
Full
Reduced
Full
Reduced
Vestigial
Long
Long
Vestigial
Vestigial
Long
Long
Vestigial
Number
of
offspring
810
818
113
119
69
63
5
3
Contribution
from F1 female
n
N
n
N
N
n
N
n
r
R
r
R
r
R
r
R
v
V
V
v
v
V
V
v
Class
P
P
R V
RV
NR
NR
DC
DC
a. Draw a genetic map that shows the distances between these genes.
RF for NR = 69 + 63 + 5 + 3/2000 = 0.07
RF for RV = 113 + 119+ 5 + 3/2000 = 0.12
N_____7 map units_______R______12 map units______________V
b. What is the degree of interference for these genes?
C of C = 5+3
=
8
= 0.47
0.07 x 0.12 X 2000
17
D of I = 1-0.48 = 0.53