Basic Color Genetics

This article is meant to be an introduction to color genetics and therefore contains a mix of technical terms and layman's terms for beginners. DO NOT be discouraged if you don't understand everything from reading this article the first time; if there is a section you are confused about just reread that section or the whole article again and it should make more sense. If you are frustrated after reading the article a few times and still don't understand, send me an email, I'll be glad to help you through it! (PJ Dvorak)

There are 5 main genetic pairs or series that make up color genetics in rabbits (A B C D and E). They are genetic pairs because each rabbit has exactly 2 genes in each of these 5 series. This means that 5 genes, one in each series is received from the sire; and 5 genes, one in each series is received from the dam. Therefore neither the sire nor the dam may pass on more than one or less than one gene per series.

Out of these 5 there are 3 absolute dominance series (A B and D). Absolute Dominance means that the rabbits color is a direct result of the most dominate gene in the pair and that the second gene has no effect on the rabbits color weather it is equal or less dominate. For this reason these 3 series are the easiest to understand, and will be the focus of this article. Many breeders will have no need for knowledge beyond these 3 series, so if you understand and master these you will be a genetics guru to most!

B SERIES

The first series will be the B series also referred to as the recessive series. For those of you wondering why I didn't start with A, don't worry I haven't forgotten it. The B series has two genes; the dominate gene is represented with "B" and the recessive gene is represented with "b". When writing out a rabbit's genetic code the most dominate gene is always written first; therefore there are only three different combinations a rabbit can have in this series: BB Bb and bb. Because this is an absolute dominance series, if the rabbit has the dominate gene "B" then it will be black, otherwise it will be chocolate. So both BB and Bb will be a black rabbit and only bb will result in a chocolate rabbit. For this reason I refer to the recessive "b" as the chocolate gene. So a rabbit may have no chocolate genes and be black (BB), have one chocolate gene and be black (Bb) and will only be chocolate if it has two chocolate genes (bb). Now we'll take a look at what this means for breeding. Let's assume you breed two chocolates together (bb x bb), the sire must pass one of his two chocolate genes on to his offspring however since he has only chocolate genes this is all he can pass on and the same is true for the dam (see fig 1). So if you breed two chocolates together you can only receive chocolates in the litter NO BLACKS! Naturally the same is true if you breed two blacks together and neither of them are carrying the chocolate gene (BB x BB), the resulting litter will be all black with no chocolates (see fig 2); and common sense will tell you that anything bred to a black not carrying chocolate gene will have the same results (see fig 3 BB x Bb & fig 4 BB x bb).

Now you know that two chocolates will never produce a black, however it is possible for two blacks to produce a chocolate. Let's assume you breed two blacks and both of them are carrying the chocolate gene (Bb x Bb). In this case there are three possible combinations: BB if both parents pass the dominate gene, Bb when one parent passes the dominate gene while the other passes the chocolate gene and bb when both parents pass the chocolate gene (see fig 5). Take a closer look at fig 5, notice there is one box out of four with BB, this means that approximately 25% of this litter will be black rabbits that do not carry the chocolate gene even though both parents do. Also there are two boxes with Bb, this means that approximately 50% of the litter will be just like the parents and be black rabbits with one chocolate gene. Finally there is one box with bb meaning that approximately 25% of this litter will be chocolate kits.

There is only one more combination I have not discussed and that is breeding a black with one chocolate gene to a chocolate (Bb x bb). You should try this one on your own while I walk you through it. Draw a square with four sections just like the others but leave them blank. On top will be the two genes from the sire and he will be our black that has one chocolate gene. Above the top left box put a "B" and above the top right box put a "b" (fig 6a). On the left will be the genes from the dam and she will be our chocolate, so to the left of the top left box put a "b" and to the left of the bottom left box put another "b" (fig 6b). Almost done, the last step is to fill in the boxes which represent the kits. In each box write in the gene received from the sire so that each box has one gene that corresponds to the gene at the top of the columns (fig 6c). Next in each box write in the gene received from the dam so that each box now has two genes, the second corresponding to the gene to the left of each row; also remember that the most dominate gene should be to the left and the lesser dominate gene to the right in each box (fig 6d). When you are finished you will have two boxes with Bb and two boxes with bb, which means this pairing will produce approximately 50% black that have one chocolate gene like the father and 50% chocolate kits like the mother.

D SERIES

The D series, often referred to ass the dilute series is very similar to the B series. Just like the B series there are two genes "D" being the dominate gene and "d" being the recessive gene. The difference being a rabbit carrying the double recessive dd will be a blue rabbit. The same rules for breeding chocolates also apply to breeding blues. This means that two blues (dd x dd) will never produce black kits, a black that does not carry blue (DD) will never produce a blue so on and so forth.

So that's it...right? Not exactly, what if I asked the question "Can two blues produce a chocolate kit (dd x dd)?". The answer to this question is more complicated because now it involves both the B series and the D series at the same time. This is where most beginners and even some more experienced breeders start to have trouble, so be prepared to read this section over again. To be fair I will rephrase my question "Can two blues who each carry one chocolate gene produce chocolate kits (Bb dd x Bb dd)?" and the answer is simply NO! For the same reason that two blues cannot produce black is the same reason two blues cannot produce chocolate, and two chocolates cannot produce blues. Let's start by looking at all the possibilities from the breeding I just mentioned: BB dd, Bb dd, bb dd (see fig 7). When comparing two series at the same time start by doing both series separately and label each box (this will help when it comes to combining them later). Next take the first box from the B series, which I have labeled B1 = BB and combine it with each of the four boxes from the D series (D1, D2, D3, D4). You will notice they are all the same BB dd, and since we are only interested in knowing which colors are being produced and not the percentages of each color, there is no need to list it more than once. Repeat this process for B2, B3 and B4 and again remove all the duplicates leaving you with the three previously mentioned results. Now let's analyze each of them separately. First is BB dd, this rabbit has no chocolate genes and two blue genes so it must be blue. Next Bb dd, this rabbit only has one chocolate gene so it cannot be chocolate and two blue genes so it is also blue. Finally bb dd, this rabbit has two chocolate genes so it must be chocolate; however it also has two blue genes so it must be blue. The answer is: a rabbit that has both two chocolate genes and two blue genes is a Lilac! So when you breed two blues and both of them carry one chocolate gene you get blues and lilacs.

Now that we know what a lilac is, let's look at how this implies to breeding. Since lilacs have both two chocolate genes and two blue genes it is safe to assume that a lilac is both chocolate and blue at the same time. This means that the same rules for chocolates apply to lilacs and also the same rules for blues also apply to lilacs. So two lilacs cannot produce black (rule from chocolates and blues) and two lilacs cannot produce chocolate (rule from blues), two lilacs cannot produce blue (rule from chocolates) which means two lilacs (bb dd x bb dd) can only produce lilac offspring (see fig 8). We can take it a step further, breeding lilac to chocolate (bb DD x bb dd or bb Dd x bb dd) can only produce chocolates and lilacs while breeding lilac to blue (BB dd x bb dd or Bb dd x bb dd) can only produce blues and lilacs (see fig 9-12).

As a review we discovered two chocolates cannot produce blacks or blues; however two chocolates can produce lilac if and only if both are carrying the blue gene similar to the example of two blacks producing chocolates. The same applies when crossing two blues to produce lilac when and only when both are carry the chocolate gene. So let's explore what happens when you breed a chocolate to a blue. First is a chocolate with no blue gene crossed with a blue with no chocolate gene (bb DD x BB dd), as you can see there is only one possible outcome (Bb Dd) and the whole litter results in black (see fig 13). When breeding a chocolate with a blue gene to a blue without a chocolate gene (bb Dd x BBdd) results in both blacks and blues; while breeding a chocolate with no blue gene to a blue with a chocolate gene (bb DD x Bb dd) will result in blacks and chocolates (see fig 14-15). Finally, if breeding a chocolate with a blue gene and a blue with a chocolate gene (bb Dd x Bb dd) then the resultant litter could have black, chocolate, blue and lilac (see fig 16).

For practice, set up your own squares and see what happens when you breed a lilac to a black and two blacks that each carries one chocolate gene and one blue gene. Try each of the following (answers will be at the bottom of the article click here to view them):
Black with no chocolate or blue genes bred to lilac = BB DD x bb dd
Black with one chocolate gene and blue gene bred to lilac = Bb DD x bb dd
Black with no chocolate gene and one blue gene bred to lilac = BB Dd x bb dd
Black with one chocolate gene and one blue gene bred to lilac = Bb Dd x bb dd
Black with one chocolate gene and one blue gene bred to the same = Bb Dd x Bb Dd

By now you should know all about the four Base colors BLACK, CHOCOLATE, BLUE and LILAC, how they relate to each other and the various outcomes of breeding them together. If not, stop here and reread the sections you are having troubles with and don't hesitate to ask me for help! (PJ Dvorak)

A SERIES

The A series determines what pattern a rabbit will have. Unlike the B & D series the A series has three genes. The most dominate is "A" referred to as the agouti gene, the second most dominate is "at" also known as the tan gene and finally the least dominate is "a" otherwise called the self gene. It is important to remember that although there are three possible A series genes a rabbit must have two and only two of these genes. This means that there is a total of 6 combinations or gene pairs a rabbit may have. A rabbit may have two agouti genes AA, one agouti gene and one tan gene Aat, or one agouti gene and one self gene Aa and all of these combinations will result in an agouti patterned rabbit. A rabbit may have two tan genes atat or one tan gene and one self gene ata and these two combinations will result in a tan patterned rabbit. Finally a rabbit may have two self genes aa which is the only combination that will result in a self rabbit. A rabbit that has two agouti genes (AA) can only produce agouti and because the self gene is the least dominate an agouti carrying one tan gene (Aat) can only produce agoutis and tan patterned kits. Tan patterned rabbits can never produce an agouti unless bred to one, however may produce self if they carry the self gene. Finally self rabbits will never produce agouti or tan when bred to another self rabbit.

Once you know how the A series works and you remember how the B and D series work; combining them is simple. All three of the patterns can combine with one of the four base colors to determine the final color of a rabbit. For example there is black-agouti also known as Copper, chocolate-agouti not yet recognized, blue-agouti known as Opal and lilac-agouti known as Lynx (not yet recognized). For the tan pattern there is Black Otter, Chocolate Otter, Blue Otter and Lilac Otter. For the self pattern the four base colors are themselves Black, Chocolate, Blue and Lilac (not yet recognized).

This concludes Basic Color Genetics. I hope you have a better understanding of these three series now than before you read the article. If not please read it again and don't hesitate to email me with any questions! (PJ Dvorak) click here to find a guide containing all the different combinations from these three series along with their corresponding color.

Black x Lilac Breedings
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