Question

A cross is made between a black and a white true breeding Andalusian fowls. What will be colour of next generation birds?

Answer 1

Answer is 'speckled' in appearance.

Explanation:

In Andalusian fowl, Fb allele determines black plumage and Fw allele determines white plumage: both in homozygous combination.

In heterozygous FbFw condition, both alleles express themselves: i.e. the bird will possess both white and black feathers. Thus heterozygous chickens show speckled appearance.

This is an example of CO-DOMINANCE.