Wolf (Canis lupus). Photo © Doug Smith · Wikimedia Commons · Public domain
The original wolf no longer exists worldwide because of hybridisation with the domestic dog, a species derived mainly from a different, colour-polymorphic canid species.
The wolf is extinct because its phenotype has changed, not just by degree but categorically with the conversion of an originally colour-monomorphic species to a hybrid showing discrete colour-morphs such as the dark morph pictured here.
Robin and the Honey Badger, 15 March 2016