The D Locus: How do you like your Vodka?
This post is Lesson 3 in our Rabbit Genetics Illustrated series.
The D Locus has only one question on it's mind. How do you like your Vodka? Do you drink it straight, or do you mix it with water? That's because this D stands for Dilution.
The D Locus is home of the Dilution gene. It dictates if you are going to get your rabbit colour straight up at full strength, or if you are going to get a diluted version.
As we learned in the previous lesson, all rabbits can be described as being either Black based or Chocolate based. The Dilution gene transforms those two options into four. The Dilution gene changes Black based rabbits into Blue based rabbits, and Chocolate based rabbits into Lilac based rabbits. This interaction between these two genes gives us what you can think of as the four primary colours that all rabbit colours are based on and often named after. They are Black, Blue, Chocolate, and Lilac.
Both Blue and Lilac appear as different shades of grey. They can at times be difficult to tell apart especially to a less experienced person, but they are distinctly different. Blue is always cool toned. Ideally it should be a dark and rich blue tinted slate grey but it can at times appear like a medium grey. It is called Blue because in proper lighting it does look like a cool blue grey. Lilac on the other hand always has warm undertones. Lilac will look like a medium to light grey. In proper lighting, it has a warm pinkish hue to it. The Dilution gene also affects the rabbit's eye color in both Blues and Lilacs, making the eyes look more grey-brown rather than brown.
The Dilution gene is recessive and works exactly the same way as Chocolate. A rabbit can carry one copy of this gene, however two copies are needed for it to be physically seen. Because it is recessive, it is noted with a small "d". When a rabbit has two copies of this gene, it is marked as "dd". The lack of this gene is marked with a capital "D".
For simplicity's sake, once again at this moment we are ignoring all the other possible pattern expressions and using only plain Self rabbits in our examples. Here is a diagram showing you the possible combinations of "D" and "d" on Black based rabbits, Black based Chocolate carrying rabbits, and Chocolate based rabbits.
When it comes to how this gene affects breeding results, the outcomes are very similar to our previous example of Chocolate since both genes are recessive. Two copies create a rabbit that is visibly diluted, while a single copy is simply carried otherwise unseen.
If you breed two "DD" rabbits together, you will always only get "DD" babies.
If you breed two "dd" rabbits together, you will always only get "dd" babies.
If you want to know what will happen when you breed "Dd" rabbits, we once again go back to our handy dandy Punnet squares to figure this out. For the sake of simplicity, we will only use Black based rabbits who do not carry Chocolate in this example. When diluted, our Black rabbits will be turning into Blue rabbits. The same results will apply to Chocolate rabbits, except those would be turning into Lilac rabbits once diluted.
50% chance of being Dd
25% chance of being DD
25% chance of being dd
50% chance of being dd
If you are looking at a Chocolate rabbit or a Black rabbit, you know they must be made up of at least one "D". However unless you have some other information to go on, you might not know if they are possibly carrying dilution.
You would mark the Chocolate rabbit as being "bb D_".
If you know that the Black rabbit carries Chocolate, you would mark it as "Bb D_".
If you know that the Black rabbit does not carry Chocolate, you would mark it as "BB D_"
Lastly, if you're not sure if the Black rabbit carries Chocolate or Dilution, you would mark it as "B_ D_"
Continue forward to Lesson 4!