- Nov 2, 2013
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I had no idea that birds were opposite from mammals in sex determination!! Thanks! Very interesting on how nature evolves and works sometimes. Personally, I found out I have Neanderthal DNA - that explains alot!!Mammal and chicken genetics have a lot in common.
Each mammal or bird has chromosomes in pairs, one from the mother and one from the father. Each chromosome has many genes. For each trait, the creature has one gene from the father (maybe naked) and one from the mother (not-naked) For most genes, one is dominant over the other (so the creature might have feathers or fur, but carry the recessive gene for being naked or hairless.) You only see the effect of the recessive gene if the creature gets one copy of the recessive gene from each parent.
That far, mammal and bird genetics work the same. It's just a matter of learning what genes are known for this species.
But sex determination is backward: male mammals are XY, female mammals are XX, so the male determines what sex the offspring is. But male birds are ZZ and female birds are ZW, and the female determines the sex of the offspring.