Equus ferus

Equus ferus is the species to which both the domestic horse (Equus ferus caballus) belong. such as its extinct Eurasian wild ancestor (Equus ferus ferus), known as the tarpan, as well as the Przewalski's horse ( Equus ferus przewalskii), a wild taxon that still lives in the steppes of central Asia.

Nomenclature

The tarpan was first described by Johann Friedrich Gmelin in 1774. Gmelin had seen the animals in 1769 in the Bobrovsk region, near Voronezh. In 1784 Pieter Boddaert named the taxon Equus ferus, based on Gmelin's description. The last tarpan died in the Moscow Zoo in 1875. Without knowing Boddaert's name, Otto Antonius published the name Equus gmelini in 1912, again referring to Gmelin's descriptions.

The domestic horse, called Equus caballus by Charles Linnaeus in 1758, descends from the tarpan. In a strict application of the rules of the International Code of Zoological Nomenclature, the tarpan was namedE. caballus ferus.

In 2003, the International Commission on Zoological Nomenclature issued a standard, known as Opinion 2027, which established an exception to the principle of priority of scientific names so that the names of wild subspecies prevailed over domestic ones of 17 species, and thus avoid the paradox of the oldest lineages being named as subspecies of their domestic descendants. Among the taxa included were horses, which is why the scientific name for the species, encompassing domestic and wild horses, is Equus ferus, with domestic horses being called E. F. caballus, the tarpan E. F. ferus,and Przewalski's horse E. F. przewalskii.

Taxonomy

Studies have been carried out between the two living subspecies of this species. A molecular study in 2009 using ancient DNA (recovered from paleontological remains) places the Przewalski's horse in the same species as the tarpan, and therefore the domestic horse. Subsequent analyzes of mitochondrial DNA suggested that the Przewalski horse and the tarpan diverged about 160,000 years ago. The Przewalski horse karyotype has one fewer pair of chromosomes than the domestic horse karyotype, either due to fission of chromosome 5 of the domestic horse in the Przewalski horse or fusion of chromosomes 23 and 24 of the Przewalski horse in the domestic horse. In comparison, the chromosomal differences between domestic horses and zebras have numerous translocations, fusions and inversions. The Przewalski's horse is known to have the highest number of diploid chromosomes among all equine species. The Przewalski horse can be crossed with the domestic horse and produce fertile offspring (with 65 chromosomes).