The genetics of animal colours fascinate me. I remember when I was a kid, my brother kept Syrian hamsters and they bred continuously. I used to draw up Punnett squares to predict the colour of the offspring. We only had wild colour and pied ones, so it wasn’t too hard. 🙂 That was long ago! There are many different hamster colours now, like black, cream, lavender…
As a teenager, I was obsessed with horses. And I mean obsessed! I lived and breathed them. Horses were the first love of my life. I learned everything there was to know about them, including their colours. I dreamed about a snow white, blue-eyed albino Arabian horse. I drew this particular horse and wrote stories about him. I called him “Fantasy”. Oh, to be 14 again!! I actually found one of those historic drawings I made of Fantasy:
It took me a while to realise that albino horses didn’t exist. About 25 years, to be exact. A few years ago, a foal was born here in the kibbutz that looked almost like the Fantasy of my teenage dreams. Almost, but not quite. He had blue eyes and a pink nose, but his coat was a very pale cream colour, not totally white.
I was mystified. I had never seen a foal like that. I had only ever seen dark coloured foals. Even grey and white horses are usually born black or brown and gradually turn a lighter colour over the years. How could this dark brown mare have such an unusual looking foal? So I started doing some research into horse colour genetics, and at some point, when I found out who the father of this foal was, understanding dawned. You see, it works like this:
The basic colour of a horse can be either red, bay, brown or black. On top of that, they can have several diluting and modifying genes. The father of this foal is a palomino, which means he is a red horse with one dilution gene. The lightbulb in my head went off when I realised the mare was not actually a brown, but a smokey black; a black horse with one dilution gene, making her look brown. Now, this foal was lucky enough to get two doses of the dilution gene on top of a basic red coat. What you get is a cremello! A cream-coloured horse with blue eyes. Apparently, they breed these horses in the USA. I had never seen one before. There are now several cremellos in the paddock in our kibbutz; it looks like the owner of these horses is trying to breed them.
Albinism is something different. There is no true albino gene in horses. There is a gene that causes pure white foals in its homozygous form, but it is deadly, meaning that no foal born with a double dose of this gene ever survives. It is called “lethal white”. Most white horses are actually greys. Grey is a gene that is turned on gradually as the foal grows, so the horse is dark when it is born but white by the time it is old.
So that was horse colour genetics. It isn’t too hard to understand if you do some research. Next, we adopted a pregnant stray cat and I started obsessing about cat colours. This particular kitty was a relatively rare ginger female. I knew it was rare, but I didn’t know why. Back to Google we went! This is what I found out:
Apparently, the basic coat colour is tied to the X chromosome in cats. The gene can be red or black. So, male cats, only having one X chromosome, can only ever have one dose of a colour gene. Female cats can have two. So if they have one red gene and one black, they will be calico. That’s why there can only ever be female calico cats. How fascinating!!
I tried to predict the colour of our cat’s babies. If she was mated by a ginger tom, she would have only ginger babies. If the tom had a black basic colour, all male kittens would be ginger (getting the red X from the mother) and all females would be calico. Well, it turned out the father was most likely a classic black tabby! She had five babies; two ginger boys and three calico girls. There were no dilution genes here, keeping it simple and straightforward.
I loved this cat and her babies… We found great homes for all of them, but our Milky disappeared one day. I will never stop missing her. ❤
Then, the rabbits happened. Which is where I got into trouble. Rabbit colour genetics are really, really complicated. I have studied and searched and I still don’t understand the first thing about it. There are many different genes and everything interacts. The basic wild colour is agouti, which appears brown but is in fact a mix of grey, brown, cream and black – in which every hair has all four colours, like this:
A very good way to blend in to your surroundings! The thing is, agouti comes in different shades. 34 of them, to be exact. One of those is chinchilla. We got a couple of those in the latest litters. Apart from agouti, there are also solid colours, dilutions and extensions. All possible basic coats and mutations together can produce hundreds of different shades. On top of that, there are the patterns. The spotted (broken) pattern overlays the original colour like a sheet with holes in it. What you get is this:
This particular pattern is called a ‘charlie’. I love charlies. Love them!! . But I think the pattern is frowned upon by show breeders. Charlies are the result of a double dose of the broken gene (as far as I understand). There is also something called a ‘false charlie’, which is when the pattern looks like a charlie but is actually genetically something else. In that way, it IS acceptable on the show table. Oh, forget about it already! I don’t get it.
Then there are the whites. There is red-eyed white and blue-eyed white, which are two totally different genes. The white is basically an un-holey sheet (hee hee) covering up the genetic colour of the rabbit. The red-eyed white is dominant and it is in fact albino, I think, but you’re not supposed to call it that. The blue-eyed white is recessive and I think is amazingly pretty. Breeders don’t like it, because a single dose of the gene can give bunnies random white spots and a very peculiar, violet eye colour. We’ve got a few of them, like Blue (left).
There are many, many more colours and patterns. Whenever I try to understand it all, I get lost. The only thing I can say is: they are all pretty. As pets, they are all perfect. Look at all these cuties!