Extra Credit!

aww!

I probably should have done this a long time ago.

So a while back, in December, this beautiful dog named Sugar had a litter of twelve puppies! I saw the pictures and I automatically thought about genetics.

















Apparently, so did my teacher because now it's an extra credit problem.

Here's the key for the genotypes

BB=black lab, no chocolate
Bb=black lab, chocolate carrier
bb=chocolate lab

Yellow Lab's fur color is controlled by a recessive epistatic gene, which "hides" the dominant dark fur gene.

EE=no yellow
Ee=yellow carrier but looks black or chocolate
ee=yellow Lab


So we can see that the mom is a yellow Lab and from the picture, we can tell that her genotype is eebb because her nose is not black. It's brown.

Since 5 out of 12 puppies were chocolate and 7 out of 12 puppies were black, we know that the father can not carry a recessive gene because then there would be a chance of one of the puppies being a yellow Lab. But the father would have to carry at least one little "b" in order for some of his offspring to be chocolate Labs. Therefore, the father's genotype is EEBb.

Below are Punnett squares with predicted genotypes of the offspring. It splits into half: one half being chocolate and the other half being black. This is close to the actual outcome.