Question

When chickens with splashed white feathers are crossed with black-feathered birds, their offspring are all slate blue (Blue Andalusian). When Blue Andalusians are crossed with themselves, they produce splashed white, blue, and black offspring in the ratio 1:2:1 respectively. Show the results of the crosses below, phenotypically and genotypically.

A. white splashed x blue
B. blue x blue
C. blue x black

Answer 1

Crosses between chickens with different feather colors illustrate incomplete dominance. Crosses between white splashed and blue result in blue offspring, two blue chickens produce a 1:2:1 ratio of splashed white, blue, and black offspring, and blue crossed with black also results in blue offspring.

Step-by-step explanation:

In genetics, the cross between chickens with different feather colors is explained by the concept of incomplete dominance. The splashed white chicken is assigned an allele sw, whereas the black chicken has an allele B. Blue Andalusian chickens have a phenotype resulting from the heterozygous genotype Bsw.

A. When splashed white (swsw) is crossed with blue (Bsw):
All offspring will be Bsw, displaying the blue phenotype.

B. When blue (Bsw) is crossed with blue (Bsw):
The expected phenotypic ratio is 1 splashed white: 2 blue: 1 black, which translates to the genotypic ratio of swsw: Bsw: BB. This is demonstrated using a Punnett square where Bsw parents produce offspring with genotypes and phenotypes in the ratio of 1 swsw (splashed white), 2 Bsw (blue), and 1 BB (black).

C. When blue (Bsw) is crossed with black (BB):
All offspring will be Bsw, displaying the blue phenotype.

The progeny from a cross between white splashed and blue is all blue (Bsw); a cross between two blue chickens results in splashed white, blue, and black offspring (genotypic ratio swsw:Bsw:BB); a cross between blue and black results in all blue offspring (Bsw).