Repulsion Linkage
| |
p
2
AB |
1-
p
2
Ab
|
1
- p
2
aB
|
p
2
ab
|
p
2
AB |
(p/2)2
AABB |
AABb |
AaBB |
AaBb |
1-
p
2
Ab |
AABb |
AAbb |
AaBb |
Aabb |
1
- p
2
aB |
AaBB |
AaBb |
aaBB |
aaBb |
p
2
ab |
AaBb |
Aabb |
aaBb |
(p/2)2
aabb |
We can collect the relative proportion of each of the four classes
of phenotypes and develop the following table:
| Type |
Proportion
Expected |
Observed
Designation |
| A_B_ |
4
- 2(1- p2)
- p2
= 2 + p2
4
4 |
r |
| A_bb |
(1
- p)2
+ p(1 - p) + p(1 - p) = 1 - p2
4 4 |
s |
| aaB_ |
(1
- p)2
+ p(1 - p) +p(1 - p) = 1 - p2
4 4
|
t |
| aabb |
p2
= p2
4 4 |
u |
Now for repulsion linkage, s and t are the observed numbers of parental
classes. The recombinant (non-parental) classes are u and part of the
r class. With closer linkage the r and u classes should decrease, while
the s and t classes will increase. The ratio ru/st is a measure of linkage
in repulsion.
