Suguru Mashima

Mitochondrial DNA Sequences of Various Species of the Genus Equus with Special Reference to the Phylogenetic Relationship Between Przewalskii's Wild Horse and Domestic Horse

The noncoding region between tRNAPro and the large conserved sequence block is the most variable region in the mammalian mitochondrial DNA D-loop region. This variable region (ca. 270 bp) of four species of Equus, including Mongolian and Japanese native domestic horses as well as Przewalskiis (or Mongolian) wild horse, were sequenced. These data were compared with our recently published Thoroughbred horse mitochondrial DNA sequences. The evolutionary rate of this region among the four species of Equus was estimated to be 2–4 × 10−8 per site per year. Phylogenetic trees of Equus species demonstrate that Przewalskiis wild horse is within the genetic variation among the domestic horse. This suggests that the chromosome number change (probably increase) of the Przewalskiis wild horse occurred rather recently.