Mutant gene frequencies in cats of the greater London area.

The frequencies of seven mutant genes of the domestic cat have been estimated by sampling the population of greater London, specific areas of the capital and adjoining counties. An attempt was made to diversify the method of sampling by concentrating upon certain categories of cats. In addition to the usual sightings of cats in streets and open spaces, surveys were made of cats attending a veterinary clinic, those staying at a boarding cattery, those exhibited in the household pet classes at a cat show and those in rescue centres. Although there are inconsistencies, the general impression from frequencies in present and earlier observations is that the lighter phenotypes (mackerel tabby, blue dilution and orange) are favoured by human preference, as opposed to the darker phenotypes (blotched tabby, black and non-orange). Reasons are discussed for thinking that, while human preference may be a factor in the evolution of the feline polymorphism, it is not the fundamental cause.