gerbil genetics made pretty easy
updated February 3, 2015
Meet Gene. He has the plans for every project.
Whether it's building a road or taking out the trash, Gene is on the job. He's in charge of gerbil hair colour, eye colour, tail length and everything else too.
* * * There's actually a whole lot of genes in all living things. Every gene is a piece of instruction for things to happen. And after those things happen, you get some sort of result. Maybe it's black hair all over a gerbil. Maybe it's red eyes. It could be anything. Remember that genes don't "do" anything directly. They just provide the instructions.
Genes come in pairs
Let's complicate things just a bit. Every gerbil has 2 sets of instructions for everything. One set comes from dad. We'll say it's Gene. The other set comes from mum. Let's call her Genevieve.
But only one if them is really needed for each job. The other one mostly just sits there.
Why? Well, one set of instructions is usually enough to get the job done. Sometimes both sets of instructions, genes, get used. Each does part of the job. But let's not worry about that right now. We'll get back to it later.
Dominant and Recessive Genes
Let's jump ahead and assume Gene and Genevieve are humans at the moment. Humans, like other living beings, all have two genes for everything (one from each parent). And each parent can only send one of those two genes for each thing to their baby.
So Gene and Genevieve get married and have a baby. Each of them sends the baby one set of instructions, genes, for eye colour. If both sets of instructions are the same, it doesn't matter which one gets used. Either way, it comes out the same.
If Gene and Genevieve both send genes for brown eyes to the baby, the baby will have brown eyes. It doesn't matter if the colour comes from Gene or Genevieve. Baby will have brown eyes.
If the 2 sets of instructions are different, it's not always possible for both things to happen at the same time. So just one set of instructions ends up being used. We call that gene dominant.
So if Gene sends instructions for brown eyes, and Genevieve sends instructions for blue eyes, what happens?
One of the sets of instructions isn't used. It is called recessive. You might not even know it's there when you look at their baby's eyes. Brown eyes are dominant. Blue eyes are recessive. Baby will have brown eyes.
What if Gene and Genevieve both send instructions for blue eyes? Well, not much for it as the baby can't have anything but blue eyes! Recessive genes can only make recessive traits.
Enough about people.
updated February 19, 2015
updated February 3, 2015
Wild gerbils are all the same colour called agouti (or golden agouti). Agouti isn't one colour. It's several in a particular pattern. Agouti gerbils look mostly brown, but that's just part of it. The tips of their hairs are black. And if you push the hair back, you'll see it's dark gray closer to the skin. Not only that, if you look at the belly, the hair is white or cream. Eyes and nails are black.
So many colours in a fancy pattern! It was all created by natural selection without any help from humans.
Every once in a while a change happens by accident in a gene when gerbils breed. And something might change in the gerbil. In the wild, if the change is good, then in time there will be more gerbils with the new, slightly different gene. But if it doesn't make it easier for the wild gerbils to survive and have more pups, it'll often disappear. All gone.
Agouti is a darn good colour for wild gerbils. The patterns and shades make it easier for wild gerbils to escape from predators. The dark speckled back makes it hard for birds that eat gerbils to see them in the dry grass and rocks. The light belly makes them hard to see against the sky if a predator comes from underground to catch a gerbil.
Then humans started breeding gerbils. And one day there was a mistake in the agouti gene. But it was recessive and didn't make any difference to the way the gerbil looked. But humans bred closely related gerbils together. Soon enough 2 gerbils with the same mistake in the agouti gene were bred together. So what happened?
Well, some of the pups were black. All over. All the places on the gerbil where the agouti gene makes browns and grays and whites were gone. There was nothing but black left. Well, almost. There was just a bit of stubborn white that stuck to chins and/or paws. Everything else was black.
How was Gene involved? Hard to say exactly. Turns out a whole section of the instructions for making agouti had vanished. Gone. It's a lot less work making black gerbils than agouti ones. All he had to do was paint the whole gerbil black. No fancy bits of brown or gray or creamy white.
Now people wanted to write the gene information in short code, to make it easier to keep records. Here's how they did it:
Capital letters (like A) are always used for dominant genes. Lower case letters (like a) are always used for recessive genes.
Much of the time we're not completely sure if an agouti gerbil has a recessive gene for black. So we write A- or A*. The - and the * both mean we're not sure what the other gene is.
Phew! That was a lot of information! Don't worry. It gets easier now.
So that was A for agouti. B would be next. Except there's no b genes in gerbils. At least, not yet.
So then we have C. Small complication though. C and P affect each other. So we're going to do P first, then C. Yeah, I know. Alphabet soup.
P: Pink Eyes
updated August 8, 2016
Gene "bleaches" colours to lighten them.
The natural colour for gerbil eyes, P, is black. pp is a pair of recessive genes that turn gerbil eyes red or pink. It's as if the eyes are bleached and the dark pigment is washed away. They end up looking reddish because blood is red, not white. They often appear a dark ruby red but can be lighter depending on the gerbil's colour.
Unless you look carefully, you might not notice your gerbil's eyes are red. But if you take a picture with flash, the light will reflect off the eyes and then they will look very bright indeed! You might consider using the red eye remover in your photo editing software. Avoid using flash if not necessary. Not shooting straight at the eyes helps too. Unless you like the bright red look! (Some people think Solar's bright eyes in this pic look freaky.)
pp strips out the black stuff that naturally protects the eyes from bright light and helps with good vision. Without it, more light enters the gerbil's eyes. Bright lights might even be uncomfortable for them. Their vision is not quite as good as gerbils with black eyes.
Occasionally they have to spend a bit of extra time trying to focus and have to move side to side to help them see how far away things are.Frosty, a pink-eyed white (PEW), demonstrates. At the beginning of the clip, you see her waver a bit to one side to help her see better. Then she runs around the tank and just before vanishing underground, she stretches up and sways side to side while taking another good look.