A long haired hamster is mated with a short haired hamster Half of the offspring are long haired and half are short haired What does this concludes about the long hair parent hamster?

Answer 1

It concludes there was a shorthaired hamster somewhere in its lineage.

Hamsters' hair length is controlled by genes, and they call the results of the genes "traits." It receives one from each of its parents. Let's use an H to signify the genes--a capital H for longhair, a small h for shorthair.


There are three possible outcomes when you breed two hamsters: the babies will receive two longhair genes, two shorthair genes, or one longhair and one shorthair gene--or in genetics parlance, they can be HH, Hh or hh. The gene for long hair is dominant--if the hamster receives at least one longhair gene, it will be a longhair hamster. Short hair is a recessive trait--it needs to receive two shorthair genes to be shorthaired. (I know what you're thinking: what if an animal receives two dominant genes? In that case, not only will the hamster be longhaired, but all of its children will be longhaired because, no matter what, it will pass on a longhaired gene.)


In this case, we've got a hamster that had, say, four babies. Two of them are longhaired, two shorthaired. The longhairs are easy to understand--longhaired parent, longhaired babies. The shorthairs mean the longhair had a shorthair gene to pass on, which means that somewhere in this hamster's lineage there was a shorthaired hamster. And that doesn't necessarily mean its mother or father was shorthaired--it's great, great, great, great grandma, six generations removed, could have been shorthaired. It had always been bred longhair x longhair so the gene didn't get a chance to express itself, but when you threw this shorthair into the mix, an animal with two shorthair genes (if it had a longhair gene it would have been a longhair), the recessive shorthair gene finally got a chance to express itself.


Now here's the fun part: if you breed two Hh hamsters, you have a 25 percent chance of producing an hh shorthaired one.