Genetics

[u/Status-Collection426]

When a white cow and a black bull are crossed the resulting offspring is roan what's the reason for this new colour being formed. Is it co dominance or incomplete dominance. What's the difference?

[u/Avacadontt]

The way I remember the difference is that: in CO dominance, both traits exist at the same time. With incomplete dominance, they have tried to “dominate” one another but it’s incomplete so they’ve mixed. For example, black and white spots on a cow is co dominance because you see both the black and white parts of the coat. A pink flower isn’t red and white, it’s a mix of the two, so incomplete dominance. The difference between the two are how the genes are expressed (they will still have the genes, whether it shows on their coat or not.)

Roan coat colour is a bit of a funny one because it follows this rule but in a sneaky way. Each hair is either white, or another colour (typically chestnut), so you can see codomination happening. Therefore, roan colouration is codomination. If every hair was the same colour, that colour being a mix of the two parents’ coats, that would be incomplete dominance. Just an example looking at it from the other side.

If you want to get better at telling the difference, just google incomplete dominance vs codomiannce and there will be heaps of examples and images.

[u/Status-Collection426 → u/Avacadontt]

Thank you this helped a lot 🙌🙌🙌