This is one of the more complex gene sets. Not only does this set have dominant and recessive genes, but it also has genes with co-dominance and slight dominance, and, just to keep things interesting, even one gene that is affected by temperature! Eek! There are five different genes in this set, listed in dominance: C, cchd, cchl, ch and c. The C locus is responsible for the restriction of color pigment on the coat. It affects the intensity of the melanin (black/brown- eumelanin and yellow/red- pheomelanin) in the hairs. The normal (or dominant) form, C, is considered “full color concentration.” On the opposite end of the spectrum is the c gene which will show a complete loss of color, or an albino.
C: FULL COLOR SATURATION
- Most dominant gene, dominant over cchd, cchl, ch, and c.
- Common varieties of C: chestnut, opal, amber, black, blue, chocolate, otter
- Possible gene combinations of the C locus with C as the dominant gene: CC, Ccchd, Ccchl, Cch, Cc
C is full color saturation- all the melanin is present in the hair.
cchd is chinchilla dark. The cchd gene reduces the yellow saturation (pheomelanin) and the yellow is usually reduced to white. There is little to no effect on eumelanin. cchd will allow the production of some but not all the color pigment of your rabbit. If your rabbit is agouti (A), white bands will appear between the dark color bands. If your rabbit is tan (at), the cream and/or orange markings will turn white. This gene also affects eye color, and eyes are often blue-gray.
The rabbits to the left are a fun example of the chinchilla dark gene- one is expressing the gene and one is not.
cchl: CHINCHILLA LIGHT
cchl is chinchilla light, or sable. This gene also reduces most of the yellow saturation (pheomelanin) and removes some of the darker pigments (eumelanin), giving the rabbit a shaded look. The effect is like that of the chinchilla gene, but further lightens the black, turning it into more of a sepia color. Unlike cchd (chinchilla dark), this gene will leave the eye color dark.
This gene is sometimes called the 'shaded' gene although 'sable' is a more correct term since true shadeds such as torts do NOT possess the sable gene.
This gene possesses a special trait from other genes- incomplete dominance. With other genes, when you pair that gene up with another copy or one that is recessive, then the dominant gene is expressed. However, when you double up the sable gene, you get a completely different result- a SEAL rabbit! Two copies of the sable gene produce a dark sepia colored rabbit that almost appears black. In the photo to the left, the shading was only visible with a very strong flash.
The second to last gene in the C locus is the Himalayan (or Californian) allele. This gene results in a totally white coat on the warmer parts of the body, and dark points on the cooler parts of the body (nose, ears, tail, feet). This is a curious allele, as it is sensitive to external temperature as well. The colder the temperature, the darker the color, and it can and will change. In the summertime the colors tend to fade and then they become more intense again in the winter. Any part of the rabbit which is exposed to cooler temperatures can grow more colored fur, which can result in “smuttiness,” especially around the rump or on the dewlap. ch dominant rabbits have ruby (pink) eyes. Rabbits showing this gene are often called pointed white.
This allele is the most recessive in the C locus. It is a true, ruby (pink) eyed albino, so an all white rabbit with ruby eyes. This allele prevents ALL pigment from forming and must be homozygous (cc) to be expressed. This allele stops all color from being expressed.
This is a curious allele, as it is a “mask” for the rest of the rabbit’s color and pattern. Think of it like a cloak laid over the rabbit, hiding the other loci. The loci still exist, they are just not visible. You can determine what genes are present in the other loci by studying the rabbit’s pedigree and/or test breeding.