Really, lilac and chocolate colors appear to be definitely striking, especially when in their perfect soft tone, which gives pleasure for a while. How does an ancient British breed that has originated from English shorthaired cats of last century have possessed these exotic colors? After all for a long time these have been a prerogative of oriental breeds solely - Burmese, Siamese, Oriental.
To answer this question one should first of all remember genetical bases of these colorings. Sometimes one can hear holders saying: "this cat carries a lilac gene". But there's no any lilac gene in nature! Lilac color is a diluted variant of chocolate, like light blue is a diluted black and cream is a diluted red. Indeed color dilution is determined genetically: a recessive allele d of Dilution is responsible for this. Hence a cat possessing a couple of dd alleles in its genotype has a diluted variant of coloring. What color exactly? This depends on the status of other genes. Among them there's a Black gene in particular. However a dominant allele of this gene doesn't provide a black coloring, but controls for the presence of a black pigment - eumelanin. The distribution of the pigment in coloring is defined by a set of other genes. As for recessive allele b from this locus, it produces an oxidized kind of pigment - not black but brown. That's why a cat with bbD genotype has a chocolate color, and the one with bbdd - a lilac color.
The recessive Dilution allele initially has been widely distributed in European populations of domestic cats and moved on into British breed in natural way during first steps of its formation - that's why blue color is the most popular and also one of the oldest in this breed. And the history of a Black gene is that in European cats it has been represented by a dominant allele only. Cat populations in Indonesia and Malaysia are somewhat different - the recessive allele b never has been uncommon there. These are the oriental cats, the ancestors of Siamese, Burmese and Oriental breeds that brought this allele in European countries in the beginning of the 20th century. It's clear that lilac and chocolate variants have quickly appeared in these breeds.
Rising of Persian color-points, however strange it is, has become the next step on the way to introduce the allele in the British breed. The Siamese cats of the old type, which carried this allele, had passed it to its progenies by mating solid-colored longhaired animals. The progenies appeared to be carriers of cs alleles of the Siamese color. Mating of these animals during next several generations could have led to a homozygous form of this allele. This is the way The Persian color-points have appeared, lilac and chocolate Persians were the by-products of this breeding program. However the former, unlike color-points, which have been under the thorough control of holders, haven't become widely spread. That's why the chocolate color allele has come into the British breed in 80-ths mostly from Persian color-points, in the very way it came into Persians from Siamese cats. Thus, besides chocolate-colored ones the lilac British cats have appeared. It would be interesting to note that in the British breed the situation with these colors was nearly opposite to that in the case of Persians. The solid-colored chocolate and lilac British cats developed quickly and have outstripped the color-point ones if not from the point of official recognition but by wining the sympathy of public. Perhaps, this reaction was due to some kind of a stereotype of perception of an acromelanistic-colored cat that was closely associated with Siamese cats.
Besides, one may consider probable the spontaneous introduction of the chocolate color alleles in the population of shorthaired European cats. In the beginning and the mid of this century the Siamese and Burmese cats often mated with representatives of other breeds or ordinary ones by request of the holders-experimentators or on their own. But the history of British cats seems not to include cases when lilac, chocolate or color-point colored kittens appeared. Apparently, Persian color-points have become the only source of b and cs alleles for British breed. The circumstantial evidence of this fact is common detection of longhair carrying in exotic colored British cats. However the major part of nurseries specializing on the chocolate and lilac colorings, such as English MISSKIN, Netherlands BAGOAS, PANDA, DIASPORA, HERKENRODE and French CHENE LANDRY, have rid of this "Persian heritage". Holders of British cats, when applying new colorings have saved time needed for stabilization of breed characteristics in animals by means of introductory interbreeding with Persians. In fact they have needed to rid the herd with new color variation of a single recessive allele of long hair. And in the case of using of traditional Siamese (Thai) cats, holders would have to restore a big amount of "British" characteristics for several years - the shape of head, the color and shape of eyes, the position of ears and the texture of hair...
Nowadays all these color variants are officially recognized in almost all greatest international felinological organizations except for American CFA. It's paradoxical, but the Americans have appeared to be more conservative then the English towards the new British colorings. The standards of CFA prohibit rearing of those color variants of breed that show any signs of "oriental trace" motivating this by the necessity of the conservation of breed gene pool purity. This approach is reasonable only in the case of native breeds while The British breed can be referred to latter one with great reserve. Moreover, it's almost impossible to stop the process of introduction of new colors in aroused cat breeds: a human nature always demands inventing something new. In 1991 a systematic work on creation of British shorthaired cats of cinnamon and fawn color, most familiar for cat-fanciers in Abyssinian breed, have been started in Britain. So, perhaps, in near future we'll have an opportunity to watch British cats of these "African" colors on the cat-shows...
Translated by Tatiana Karpova (Moscow)
(MSU, Biology faculture, Dep. zoology and ecology).