Rabbit Genetics: The B Locus
There are two genes in the B Series. The dominant one is "B" and the recessive one is "b".
~ Black
"B" is the Black gene. All colors that are not a chocolate based are black based colors and thus have this gene. They have to have at least one black gene in order to be a black based color. If they have two black genes then they are homozygous for black. Thus it could not produce any other color besides a black based color. The following colors are some of the colors that are black based colors:
Black, Blue, Chestnut Agouti, Castor, Sandy Gray, Gray, Copper, Opal, Black Chinchilla, Blue Chinchilla, Sable, Sable Point, Black Tortoise, Red, Orange, Smoke Pearl, Blue Tortoise, Sable Chinchilla, Smoke Pearl Chinchilla, Black Otter, Blue Otter, Black Silver Marten, Blue Silver Marten, Black/Orange Tri, Blue/Fawn Tri, Black Harlequin, and Blue Harlequin.
Black can also carry chocolate. When black carries chocolate it is heterozygous. Meaning it is not pure for the black gene.
~ Chocolate
"b" is the Chocolate gene. Any chocolate color must have two of these genes to be a chocolate color. They have to be homozygous for chocolate. Chocolate cannot carry black because black is dominant to chocolate and no recessive gene can carry a dominant gene. The following colors are some of the colors that are chocolate based:
Chocolate, Lilac, Chocolate Chestnut Agouti, Cinnamon, Lynx, Lilac Chinchilla, Chocolate Chinchilla, Chocolate Otter, Lilac Otter, Chocolate Tortoise, Lilac Tortoise, Chocolate Silver Marten, Lilac Silver Marten.