1. Incomplete Dominance and Codominance (Non-Mendelian Genetics)
R’R’
RR’

2. Incomplete Dominance –. Both dominant genes are expressed as a
Incomplete Dominance – Both dominant genes are expressed as a “Mixture” of the two traits.
Codominance – Both dominant genes are expressed fully in the organism

3. Black Chicken – BB
White Chicken – WW
Erminette Chicken - BW
Example of Codominance

4. A black chicken and a white chicken are crossed, what is the probability of:
White Chickens _________________________%
Black Chickens __________________________%
Erminette Chickens ______________________%

5. 4) If two erminette chickens are crossed, what is the probability of:
White Chickens _________________________%
Black Chickens __________________________%
Erminette Chickens ______________________%

6. Red Flowers – RR (R1R1) White Flowers – WW (R2R2)
Pink Flowers – RW (R1R2)
Optional Annotation
Example of Incomplete dominance

7. 6) A pink flowered plant is crossed with a white flowered plant, what is the probability of:
Red Flowers _________________________%
White Flowers _________________________%
Pink Flowers _________________________%

8. 7) Two pink flowered plants are crossed, what is the probability of having:
Red Flowers _________________________%
White Flowers _________________________%
Pink Flowers _________________________%

9. 8) What cross will produce the most pink flowers?

10. Practice Problems:
Black Chicken – BB
White Chicken – WW
Erminette Chicken - BW
Example of Codominance

11. White Fur
Red Fur
Roan Fur
Example of Codominance

12. 5) Roan Bull crossed with Roan Cow, what is the probability of having:
Red Fur _________________________%
White Fur _________________________%
Roan Fur _________________________%

13. 6) Red Bull crossed with White Cow, what is the probability of having:
Red Fur _________________________%
White Fur _________________________%
Roan Fur _________________________%

14. 7)

15. 7) If we assume Incomplete Dominance in Tail Length (not the Manx gene)
TL – Long Tail Gene (Dominant)
TN – No Tail Gene (Dominant)
TL TL will produce a long tailed cat
TL TN will produce a short tail cat
TN TN will produce a cat with no tail

16. White Flowers – WW (R’R’) Pink Flowers – RW (RR’) Optional Annotation
Red Flowers – RR (RR)
White Flowers – WW (R’R’)
Pink Flowers – RW (RR’)
Optional Annotation
Example of Incomplete dominance

17. Andalusian Fowl:
Black Feathers – BB
White Feathers – B’B’
Bluish Gray – BB’

18. 11) Black Andalusian Chicken crossed with a White Andalusian Chicken, what is the probability of having:
Black Feathers_________________________%
White Feathers_________________________%
Blue-Gray Feathers_________________________%

19. 12) Black Andalusian Chicken crossed with a Blue-Gray Andalusian Chicken, what is the probability of having:
Black Feathers_________________________%
White Feathers_________________________%
Blue-Gray Feathers_________________________%

20. 11) Cross two Blue-Gray Andalusian Chickens, what is the probability of having:
Black Feathers_________________________%
White Feathers_________________________%
Blue-Gray Feathers_________________________%