Sex-linked Mutation.

[Jayd]

A sex-linked mutation is one that is carried on one of the sex

chromosomes. When dealing with sex-linked mutations in birds, it is important to

note that humans' and birds' sex chromosomes do not work in the same way. While

a human female is homozygous (which means that she has two copies of the same

sex chromosome -- "XX") and a male human is heterozygous ("XY"), it is the other

way around in birds; female birds are heterozygous, and males are homozygous.

 

This means that females can have only one copy of a sex-linked mutation (the

mutation is carried on the X chromosome), and it follows that females cannot be

split to a sex-linked mutation. If a female does not visually possess the

sex-linked trait, she does not carry it at all.