What significant transformation does Buck undergo by the end of the story?

By the end of "The Call of the Wild," Buck transforms from a domesticated pet into a creature that fully embraces his wild heritage. Throughout the novel, Buck's journey is marked by a struggle between the comforts of human civilization and the instincts of his ancestors. As he experiences the brutal realities of life in the Yukon wilderness, he learns to rely on his primal instincts, developing skills that allow him to survive and thrive in the wild.

This transformation signifies not just a physical adaptation to the environment, but also an ideological shift. Buck's final acceptance of his wild nature is illustrated when he answers the call of the wild, joining a pack of wolves and ultimately leading a life that honors his innate instincts. This journey highlights themes of survival, the influence of nature, and the idea of returning to one’s roots, culminating in Buck’s complete realization of his identity as a wild creature.