Every rabbit, no matter what color, is either black, blue, chocolate, or lilac based. This is because the rabbit has to have either the black gene or the chocolate gene making it either Black and Chocolate. Even though blue and lilac are affected by this gene, for less confusion, lets only work with Black and Chocolate.
As we learned with the A series, the capital letters represent the most dominant and the lower case letters represent recessive. Never will you have a recessive gene depicted with a capital letter. Therefore:
(B)-Black
(b)- Chocolate
Black is always dominant over chocolate and chocolate is always recessive to black.
Since we learned how to make charts in the last lesson, let's do a quick one for this gene series and then incorporate what we learned with the A series. Let's begin with a Black rabbit carrying chocolate B(b) and a Chocolate rabbit (remember because chocolate is at the bottom of the dominance list, you write any chocolate rabbit with two (b) genes.)
___B_ b
b Bb bb
b Bb bb
We can conclude that we have a 50% chance of getting black offspring and 50% chance of getting chocolate offspring. Because the chocolate parent can only give a (b) gene, all the offspring will carry a second (b) gene making the blacks a carrier of chocolate.
So if every rabbit is either black or chocolate based, what about colors like Orange where you can't see any black? Well, we assume that colors like Orange and Siamese Sable are black based unless noted otherwise. If it is known that the orange is b(b) and not (B) then it is called a Chocolate based or Chocolate factor Orange. Because phenotypically (the appearance of the rabbit) you can't see all that much difference in a black based or chocolate based Orange, they are not recognized as two separate colors. However, in some breeds black and chocolate based colors are recognized separately because of the drastic differences in the phenotype. For instance, we do not refer to a Chestnut expressing b(b) as a chocolate factored/based Chestnut, we refer to it as a Chocolate Chestnut (and a lilac Chestnut is often called a lynx). It's a little confusing but the basic point is to know that every rabbit is either black or chocolate based even if they do not appear so phenotypically.
So let's say we have a Black Chestnut carrying chocolate and tan pattern and breed it to a Chocolate Otter carrying self. That may sound a little confusing but let's list what we know about these colors first!
We know that the A series comes first and then the B series. So the Chestnut is A(at)-B(b). The Chocolate Otter is at(a)-bb. That makes it a little less confusing doesn't it? So how do we figure out what colors we can get from this cross? We'll start with a chart for the A genes and then make a chart for the B gene.
___A___at
at A(at) at(at)
a A(a) at(a)
50% Agouti, 50% Tan Pattern
___B__b
b Bb bb
b
B
b
bb
50% Black, 50% Chocolate
So now that we've discovered our chance of getting each combination of either gene we now have to "add" it up. Basically, you match up all the A series combinations with the B series combinations. Starting with the first box in the A chart and matching it with all the boxes in the B chart and then continuing on.
A(at)-B(b)- Chestnut (carrying tan pattern and chocolate)
A(at)-b(b)- Chocolate Chestnut (carrying tan pattern)
at(at)-B(b)- Black Otter (carrying chocolate)
at(at)-b(b)- Chocolate Otter
A(a)-B(b)- Chestnut (carrying self and chocolate)
A(a)-b(b)- Chocolate Chestnut (chestnut carrying self)
at(a)-B(b)- Black otter (carrying self and chocolate)
at(a)-b(b)- Chocolate Otter (carrying self)
After writing it out we can see that we will either get Chestnut, Chocolate Chestnut, Black Otter or Chocolate Otter. Even though we only have four color possibilities out of this breeding, what each rabbit might carry varies significantly. When they are born, we only know what they are by looking at them. This leaves a blank on their genotype. For example, a black otter would appear as at_-B_. We can only know which genes they are carrying by breeding the offspring to the color they could produce if they carried that gene. So if we wanted to see if one of the kits carried chocolate, we would breed it to a chocolate. If a chocolate is produced we can fill in the second (missing) gene and label the rabbit as a chocolate carrier. This concept works with all the gene series so remember it!
And there you have it. The B-series gene is a very simple one because it is only comprised of two genes. However, the more gene series you know the more complicated the process becomes to figure out color possibilities. So try it out! Pick a breeding like above and make a chart. See what colors are possible and the likelihood of them! The more you practice, the easier it will become!
