PROBLEM D Consider a hypothetical quantitative trait a weigh

PROBLEM D

Consider a hypothetical quantitative trait (a weight of some kind) affected by five loci for the two individuals (1) and (2). Assume the following:

Complete dominance at each locus. No epistasis.

The independent effect of each dominant allele is +8 lb.

The independent effect of each recessive allele is -3 lb.

The phenotypic mean for the trait = 600 lbs.

(BV= breeding value, G=Genotypic Value, GCV=gene combination value, E= environmental effect on animal\'s preformance, P=Phenotypic Value)

BV

G

GCV

E

P

(1) AaBbCcDdEe

-15

(2) AAbbCCddEE

+12

Fill in the blanks in the table above and answer the following questions:

D1. Which individual is heavier? Why?

D2. Which would produce heavier offspring (on average)? Why?

ALLELIC ACTION

PROBLEM E

Given the following values for performance of genotypes, what type of allelic action is represented in each situation?

CC

Cc

cc

Situation 1

44

33

22

Situation 2

44

66

23

Situation 3

44

44

15

Situation 4

44

40

21

	BV	G	GCV	E	P
(1) AaBbCcDdEe				-15
(2) AAbbCCddEE				+12

Solution

BV

G

GCV

E

P

(1) AaBbCcDdEe

-15

(2) AAbbCCddEE

+12

D1.Individual 2 is heavier because its phenotypic value is higher.

D2. Individual 2 would produce heavy offspring because its BV is higher.

E.

Situation 1: Gene action: additive; Degree of Dominance:0

Situation 2: Gene action: Complete dominance; Degree of Dominance:1

Situation 3: Gene action: complete dominance; Degree of Dominance:1

Situation 4: Gene action over dominance; Degree of Dominance: 2

	BV	G	GCV	E	P
(1) AaBbCcDdEe	12.5	25	12.5	-15	10
(2) AAbbCCddEE	18	36	18	+12	48