What did the rifle shot at end of chapter signify The Call Wild?

The rifle shot at the end of the chapter of The Call of the Wild signifies Buck's ultimate transformation from a domesticated creature to a wild dog. It represents the culmination of his journey back to his instincts and the wild within him. The shot also signals the end of his journey with Thornton and his return to the Yukon wilderness. It symbolizes Buck's surrender to the call of the wild and his final embrace of his true nature as a wild animal.