Rabbit Genetics: The B series
The B genes are fairly simple genes to learn, mostly because there are only two of them: B and b. That's good, because there are no parenthesis needed in place of notations, which require more typing work from me. It's easier for everyone!
B genes determine the base color of the coat, which can be either black (B) or chocolate(b). This makes it sound like we are differentiating between black and brown, but we aren't. The B genes tells us the intensity of the black color in the coat, the level of pigmentation, dark or light - a spectrum of black color. It might help to think of black based colors as clear, and chocolate based colors as muddy or washed out.
The Black Based Gene (B):
A seal holland lop kit, obviously black based
Most rabbits you see have black based coats. The black based gene is dominant over the chocolate based. This means that even if a rabbit has one chocolate based gene, the black based gene will hide it, and the rabbit will be a black based color.
The idea of a black based rabbit can be a bit confusing, as many of the B gene colors are not black at all - like orange.
The Chocolate Based Gene (b):
Chocolate holland lop kits, from Hot Cross Buns Rabbitry
The chocolate based gene is relatively rare in holland lops because it is recessive. A rabbit must have two chocolate based b genes for that lack of black pigmentation to show in it's coat. It presents as a rich yellow brown tint, helping to create colors such as chocolate point, lilac, and lynx.
Remember though, not every bunny that looks brown is a chocolate based rabbit. For example, Torts and chestnuts are technically black based rabbits, but are brown in color. Eventually you will see that chocolate based rabbits generally have richer browns than black based rabbits. Again, it is easier to think of black based as one end of the spectrum, and chocolate as the other. For example, a black tort looks pretty brown to begin with, but a chocolate tort is even more so.
That covers the basics of the B gene! Though it may seem a little complicated at first, rabbit genetics are really pretty simple. If you have any questions, feel free to email me at bunnyjeans101@gmail.com