Origin of the domestic dog matched across Eurasia and its branch is phylogenetically rooted in the same sequence as the Altai dog (not a direct ancestor). The subclade d2 hybrid haplotypes are found in 2.6% of South-West Asian dogs. Haplogroup E: Derived from post-domestication wolf–dog hybridization in East Asia, (rare distribution in South-East Asia, Korea and Japan). Haplogroup F: Derived from post-domestication wolf–dog hybridization in Japan. A study of 600 dog specimens found only one dog whose sequence indicated hybridization with the extinct Japanese wolf. It is not known whether this hybridization was the result of humans selecting for phenotypic traits from local wolf populations
Dog type were described as species by Johann Friedrich Gmelin in 1788, and by Robert Kerr in his English translation of "Systema naturae" ("The Animal Kingdom") in 1792. Today the species Linnaeus named are identifiable as dog types, not species or subspecies. Some, such as "Canis aegyptius", a hairless dog type of Peru, have been documented and registered as breeds (Peruvian Hairless Dog). There are only two categories (subspecies) of domestic dog, "Canis lupus familiaris" and "C. l. dingo", recognized by the International Code of Zoological Nomenclature (ICZN Code). Beginning with the advent of dog shows in the mid-19th century in England,