History of the domestic sheep exact line of descent between domestic sheep and their wild ancestors is unclear. The most common hypothesis states that "Ovis aries" is descended from the Asiatic ("O. orientalis") species of mouflon. A few breeds of sheep, such as the Castlemilk Moorit from Scotland, were formed through crossbreeding with wild European mouflon. The urial ("O. vignei") was once thought to have been a forebear of domestic sheep, as they occasionally interbreed with mouflon in the Iranian part of their range. However, the urial, argali ("O. ammon"), and snow sheep ("O. nivicola") have a different number of chromosomes than other Ovis species,
Class A Wild Trout Waters statewide angling regulations by the Pennsylvania Fish and Boat Commission. The official definition of Class A Wild Trout Waters is "streams that support a population of naturally produced trout of sufficient size and abundance to support a long-term and rewarding sport fishery". These streams are considered to be the best angling streams in Pennsylvania and most of the state's 67 counties contain at least one. Class A Wild Trout Waters are virtually never stocked, although many were prior to receiving their designation. There are different total biomass criteria for different species and combinations of species, but for brook trout alone,