Mouflon scientific literature as separate species, "Ovis musimon" and "Ovis orientalis". The mouflons are also sometimes treated as a subspecies of the domestic sheep, "Ovis aries", named with the same subspecific epithet as above: "O. a. musimon", "O. a. ophion", etc. Based on comparison of mitochondrial cytochrome b gene sequences, three groups of sheep ("Ovis") have been identified: Pachyceriforms of Siberia (snow sheep) and North America (bighorn and Dall sheep), Argaliforms (argali) of Central Asia, and Moufloniforms (urial, mouflon, and domestic sheep) of Eurasia. However, a comparison of the mitochondrial DNA control region (CR) found that two subspecies of urial, "Ovis
Dmitry Belyayev (zoologist) also been of great interest to Darwin. It was recognized that domesticated animals differ in several ways from their wild counterparts, but it was not known what principle of selection had guided the Neolithic farmers who had first domesticated these species thousands of years ago. Belyayev's hypothesis was that "all domesticated species had been selected for a single criterion: tameness." Belyayev further theorized that this attribute "had dragged along with it most of the other features that distinguish domestic animals from their wild forebears, like droopy ears, patches of white in the fur and changes in skull shape." In other