Overdominance

Overdominance is when having two different versions of a gene, or alleles, is better for an organism than having two copies of the same allele. Think of it like having two different types of toys to play with instead of two of the same toy.

Let's pretend we are talking about flower color. Imagine there are two versions of the flower color gene: one that gives a red flower, and one that gives a white flower. If you have two copies of the red allele, you will have a red flower, and if you have two copies of the white allele, you will have a white flower.

But, if you have one copy of each allele, you will have a pink flower! This is because having two different alleles means that the flower has the best of both worlds - it has enough red to make it pink, but also enough white to keep it light.

This same idea can apply to other traits too, like height or disease resistance. In some cases, having different alleles can make an organism stronger or healthier than having two copies of the same allele.

Overall, overdominance is when having two different alleles is better than having two copies of the same allele, kind of like having two different toys to play with instead of two of the same toy.