BREED OR SUBSPECIES? TAXONOMY OF CAT BREEDS
Species are taxonomic grouping of animals that are similar, but readily distinguishable from another, and which rarely or never interbreed naturally. For example lions and tigers are different species of big cats. Eeven where they occur together (in the Gir forest, India) they are sufficiently different in type and behaviour that they do not interbreed naturally. Species receive binomial taxonomic names denoting genus and species e.g. Panthera tigris (tiger) and Panthera Leo (lion)
Subspecies (also known as race) is the taxonomic rank below species. Members of a subspecies differ morphologically from members of other subspecies within the same species, for example the Amur tiger differs in type from the Bengal tiger. However, if they encounter each other, members of the subspecies are sufficiently similar that they readily interbreed. The Amur subspecies of tiger has the trinomial scientific name Panthera tigris altaica while the Chinese subspecies is Panthera tigris sinensis. Subspecies are generally separated by a physical barrier such as a mountain range or body of water.
Where there is a gradual change in type from one end of a species' range to the other, this is called a cline. For example Bengal tigers in a forested region may be more heavily striped than those in a more arid area of the Bengal tiger's range. Between these regions, tigers show various degrees of striping, but are still Bengal tigers.
A breed is a domesticated subspecies that, even if it arose naturally, is has been perpetuated by humans. The domestic cat is a domesticated subspecies of F silvestris and known taxonomically as F silvestris catus. It arose from the African Wildcat, F silvestris lybica. The varieties of domestic cat are breeds, some of which arose from regiona populations of mutant forms that attracted human interest. Unlike subspecies, breeds receive common names, not scientific names. A particular longhaired form is called the Persian Longhair, but is still a domesticated form of F silvestris lybica. It could be considered a sub-subspecies! When the domestic cat was considered a species, F catus, the Persian race would have been called F catus persica. A possible modern taxonomic name might be F silvestris catus var persica denoting the Persian race of the domestic cat (Var is commonly used in botany to denote "cultivated variety" aka cultivar). Breeds interbreed naturally with each other and with the parental subspecies (the random-bred domestic cat).
A subspecies arises by natural selection for a set of traits suitable to a geographic region. A breed arises through artificial selection of naturally occurring traits based on aesthetic or functional criteria. For example Persian Longhairs were considered aesthetically pleasing; Border Collie Dogs were bred to be functional.
A strain refers to a bloodline i.e. the descendants of a single significant individual. A strain might be confined to a single breed or might span several breeds (e.g. an influential sire used in outcrosses for different breeds). Newly developed breeds may comprise a single bloodline traceable to a particular individual. Longer established breeds generally include multiple strains to ensure genetic diversity.
In the 19th century, there was great interest in classifying organisms scientifically. This classification is called taxonomy. Many "species" or "subspecies" were identified and named on the basis of a single variant individual brought back or described by travellers. There was great kudos in having a species or subspecies named after you! The British Victorians seemed intent on classifying everything into ordered groups.
During the 20th century, many supposed specimens have lost their species/subspecies status; for example the "Servaline" is now known to be a Serval with a variant pattern. Many others turned out to be synonyms for the same variety. Many others are being redefined based on DNA evidence. Today, species and subspecies may be defined based on how genetically different they are and not merely on visual and behavioural differences. Before DNA techniques, the ability of species to form hybrids, and the viability and fertility of the hybrids, gave a rough indication of how closely or distantly related they were. The lion and tiger can be made to produce hybrid offspring, of which the females are fertile, but the males are not. The Bengal Tiger and Amur Tiger readiliy interbreed and their male and female offspring are fertile. The tigers are therefore more closely related to each other than they are related to the lion.
CHANGING TAXONOMY OF THE DOMESTIC CAT
Carolus Linnaeus, father of scientific classification and author of "Systema Naturae" (1758) called the domestic cat "Felis catus". Johann Christian Daniel von Schreber named the European wild cat Felis silvestris in 1775. The domestic cat was considered to a subspecies of the wild cat, and the wildcat should, under the International Code of Zoological Nomenclature system of first-gets-precedence, have become F catus silvestris rather than F silvestris. In "Anfangsgründe der Naturlehre and Systema regni animalis" (1777) Johann Christian Polycarp Erxleben used the name F domesticus. This name, and F silvestris domesticus, are sometimes seen, but are not considered valid scientific names under the rules of the International Code of Zoological Nomenclature. F silvestris is generally adopted for the wild species and F catus is sometimes seen in print for the domestic cat.
In opinion 2027 (Vol 60, Part 1, Bulletin of Zoological Nomenclature, March 31st, 2003) the International Commission on Zoological Nomenclature "conserved the usage of 17 specific names based on wild species, which are predated by or contemporary with those based on domestic forms." They confirmed F silvestris for the wild cat and F silvestris catus for the domestic cat. DNA and comparative bone research shows that domestic cats are derived from F lybica (African wildcat) rather than F silvestris (European wildcat); this updated the taxonomy to F silvestris silvestris (European Wildcat) and F silvestris lybica (African Wildcat) which are both subspecies of F silvestris (wild cat). The domestic cat therefore hovers between being a subspecies of the wildcat and a sub-subspecies of the African wildcat!
Domestic cats, F lybica/F s lybica and F silvestris/F s silvestris all hybridise freely which indicates that they are subspecies rather than species. Any hybridisation with other species, such as F chaus, F margarita, in historical times was so minimal as to be incidental to the domestic cat being a domesticated form of the African Wildcat, just as modern artificial hybrids do not make it a subspecies/descendent of F bengalensis of F chaus. Nature, incidentally, will allow some species and subspecies to interbreed with little regard for the taxonomic pigeonholes imposed on them by humans!
19TH CENTURY ATTEMPTS TO DEFINE BREEDS TAXONOMICALLY
Early travelers and cat fanciers suggested that distinct cat types be assigned scientific nomenclature as subspecies. This was based on the fallacy that the type was representative of the dominant phenotype in the region. It was also based on the Victorian love of collecting and categorising organisms and therefore "claiming" them in some way.
With the possible exception of the geographically isolated Manx, the types identified for scientific names were not representative of a dominant type. They represented an interesting trait reported or imported by travellers and 19th Century cat fanciers. The dominant type of cat in Thailand (Siam) is a moderately oriental type cat with kinked or bobbed tail and not the colourpoint cat recognised as the Siamese. The Siamese cat was considered sufficiently distinctive to be imported to England in the mid 1800s. The Chartreux was bred within French monasteries. In Britain it is not recognised as a distinct breed, let alone subspecies, as it is almost identical to the British Blue Shorthair. The Turkish Angora is the longhaired variant of native Turkish cats. Shorthaired Turkish cats also occur and the two types interbreed freely. Selective breeding from longhaired imports into England fixed the longhaired trait.
The Japanese Bobtail, the dominant form in Japan, might have been considered F catus japonica had it received sufficient attention in the late 19th century. The Persian would have been F catus persica, based on the wholly false notion that it came from Persia (Iran) rather than being developed in the late 19th/early 20th centuries from imported Angoras and the cobbier native longhairs found in Britain.
More recent breeds have never had a taxonomic name suggested. For example, the ticked ivory Singapura cat, suggested as a subspecies,was actually derived from Burmese/Abyssinian type cats taken to Singapore by an American couple. The cat type indigenous to Singapore and the Malay Peninsula is bobtailed and occurs in all colours and patterns including tortoiseshell-and-white and mackerel tabby. Other regional varieties such as the Maine Coon and Norwegian Forest Cats are naturally occurring and are now bred by cat fanciers, but these existed alongside other varieties with which they interbred. Longhair gene alone is not sufficient for these to be considered separate subspecies.
The more recently discovered Sokoke Forest Cat (from Kenya in the late 20th Century) was briefly considered to be a separate subspecies with a distinctive pattern. The Sokoke's pattern is a variation of tabby and is also found in random-bred cats in England and elsewhere. Its conformation is moderately oriental and is not confined to cats of the Sokoke region.
As it currently stands, the pet cat is the domesticated form of the African Wildcat. The African Wildcat, F s lybica, is a subspecies of the Wildcat. Were a level called sub-subspecies to exist, the domestic cat would be placed at this level below F s lybica. These will all interbreed freely and without human intervention. Interbreeding with other wildcats mentioned as possible ancestors, appears only to occur where the wildcat (or a wandering domestic cat) has no other choice of mate. If it has occurred at all, it is so minimal that it can be disregarded when considering the taxonomic status of the F s lybica and the domestic cat.
Most breeds of cat do not sufficiently represent true-breeding regional populations and are, therefore, not sub-species (with the possible exception of island populations), but represent variations within the cat's range. Were the level of cultivar to exist, the various breeds would be at this level below the domestic cat.