In "The Call of the Wild", how does Buck adapt to his environment and ultimately dominate it?

In the beginning of Jack London’s “Call of The Wild,’ Buck is a soft dog that "lived the life of a sated aristocrat."   He is dog-napped and sold by the gardener at the estate where he is “ruler” and learns a lesson about man that he will never forget.  He learns that in this new environment “a man with a club was a law-giver, a master to be obeyed, though not necessarily conciliated."   Buck becomes a harder, stronger, and more cunning dog.  He regresses to the basic nature of a dog and feels “the decay or going to pieces of his moral nature, a vain thing and a handicap in the ruthless struggle for existence."  He learns to steal food and fight as well as kill for his survival.  “The domesticated generations fell from him," and "instincts long dead became alive again."  While living with Thornton he shares a bond with the man, but feels a calling into the wild.  He leaves camp for days at a time but torn between being with the human he has grown to love and the “wolf brother” he also desires t be with creates an inner conflict in Buck.  On returning from one of his hunting trips he returns to Thornton’s camp and realizes that there is the smell of death in the air.  He attacks and kills many of the natives that have killed his beloved John Thornton and then goes off to be with his wolf brothers.