This rabbit has a coat that is mostly black, and short-haired. It is peculiar, however, in having four patches of brown hair and three of long hair (one of which shows on his back). It is supposed that these patches are due to somatic segregation, and that the rabbit is heterozygous for brown hair-color and for the long-haired Angora type of coat.
A male rabbit of peculiar interest has recently been presented to this Department by a well-known Scottish breeder. The rabbit is out of a brown (Havana) doe sired by an unknown buck. It was between eight and ten weeks old when received here on November 19th, 1928, and is of a type and size somewhat similar to the Havana or Dutch.
In colour it is mainly self black, but exhibits traces of Dutch ancestry, having white forefeet and a white nose tip. It is remarkable, however, in that there are four areas of brown-tipped hairs in its coat. These are situated on the right shoulder; a small patch at the right side just where the hind limb joins the body; a large patch on the rump, the greater portion lying on the left side, but also extending to the right, and lastly a smaller area on the left side of the rump and near the previous one. The colours of black and brown are not usually found in the same individual, this being the first case to be recorded to our knowledge.
The brown patches are not the only unusual features exhibited by this rabbit. Whilst it is mainly shortcoated, three patches of longer (Angora) hair are situated on the back towards the hindquarters. These are in close proximity to one another in a comparatively narrow strip lying along the vertebra, that nearest the tail covering the largest area. The difference in the length of the hair is considerable, as the short coat measures only 2.8 cms. whilst the Angora patches vary from 5.7 cms. to 6.6 cms. in length. An area, including part of the Angora patch, was shaved and another Angora patch was plucked out on December 12, 1928, and at the time of writing (February 2, 1929) it appears that the differentiation in the hair type is persisting. The rabbit has an exceedingly dense coat of fine texture.
Instances of unusual regional differences in characterisation have frequently been reported in plants and Drosophila, but are distinctly rare in the higher animals. They may be due occasionally to gene mutation, but more commonly are the results of abnormal distribution of whole chromosomes during cellular division. e.g., gynandromorphism. The case now under discussion would seem to belong to the latter class.
The present case is of a rabbit, out of a short-haired Havana doe which must have been homozygous for the recessive brown character and either homozygous or heterozygous for short coat. The sire was almost certainly a black rabbit and probably either homozygous or heterozygous for short coat. The rabbit described in this note, presumably heterozygous for both the characters black and shorthaired, exhibited patches of the two recessive characters, brown and Angora. This escape of these recessives was probably due to an unusual segregation of the chromosomes, which left the cells in certain areas without the chromosomes carrying the genes for black and for short hair. It is interesting to note that whilst the Angora coat is limited to a somewhat confined area, the brown patches are scattered widely. It would appear, therefore, that the abberrant distribution of chromosomes had occurred twice during development, the chromosome bearing the gene for black being the first to be abnormal in its distribution. later one chromosome bearing the gene for short hair became involved, but this lead to a lesser ultimate effect, owing to less cellular division than was the case of the variation.
The white spotting of the nose and forefeet is not considered remarkable. It is probably due to the presence of one or more of the factors controlling the Dutch pattern, which are frequently found in the Fur Varieties of rabbits.
The case of a short-coated black rabbit with areas of both brown hair and long coat is described. The possible cause of this abnormal variation through the segregation of the chromosomes is discussed.
A somewhat similar case in a rooster, as reported in Fortean Times