Color genetics of the rabbit is a complicated thing, but understanding it can be very helpful when purchasing new stock, working on a new color, developing a new color or maintaining only the varieties that are desirable to you. There are over 200 possible genotypes based on the 5 main color genes. In Rex, only 16 of those are showable.
If you need "genetics help" with your Rex, feel free to email me. Here is also a short tutorial about color genetics, I hope this helps!
Genotype= what set of gene "alleles" (or variations of a gene) does the rabbit have?
Phenotype= what do those set of genes make the rabbit LOOK like?
What does “genotype” mean?
C allele: Determines color amount that can be produced
ch: Californian allele- allows color only where there is a lower body temperature (the extremities)
D allele: Determines if the color can be dilute
I do not put this allele in my genotype on the pedigree because once you understand the concept of broken genetics it is unnecessary. There can not be “hidden” recessive genes when dealing with brokens.
So, solid to solid can only result in SOLIDS.
Broken to Solid will result in about half solid, half broken.
Broken to Broken will result in about half broken, 1/4 SOLID and 1/4 Charlie.
Charlie to Solid will result in 100% BROKEN (this is helpful to anyone breeding tricolors- the solid versions are not showable)
How to Apply this to Breeding?
Now that the color alleles are understood, they can be put together to make colors. So how does this help on a new rabbit’s pedigree?
You will find out the most pieces of the genetic puzzle when breeding your pair and observing the colors of the offspring. This is a way for you to "fill in" the unknowns.
You buy a castor buck (A_B_C_D_E_) and a black otter doe (at_B_C_D_E_) and breed them. You get a white baby, a red baby and a blue otter baby. How did this happen? What hidden recessives can you fill in for the parents? If there is a white, both parents must carry white (c). So both parents are Cc. If there was a red baby, both must carry nonextension (e)- so both are Ee. The blue otter (genotype at_B_C_ddE_) is more of a puzzle, the “otter” part most likely comes from the black otter doe, but it also could have arisen as a recessive in the castor (we don’t know whats there, so we cant fill in anything). The blue part must come from both parents carrying blue (d), so their new genotype is Dd. So from this cross more accurate genotypes were determined.
Genotypes of Recognized Rex Varieties:
B/O Tricolor A_B_C_D_ej_
Black/Orange Tricolor ej_
Blue/Fawn Tricolor ddej_
Chocolate/Gold Tricolor bbej_
Lilac/Fawn Tricolor bbddej_