Answer:
Some big themes in The Call of the Wild are civilization vs the wild, follow your instincts, and the value of work.
I think The Call of the Wild will end with Buck returning to his wolf side and becoming one with the wilderness. This goes along with civilization vs the wilderness because Buck really loves John Thornton but he finds a thrill in doing wild things like killing his own food and exploring. It also goes with following your instincts because Buck wants to go towards the wild call that he hears so often, and which when he does he can connect with his true self.
Step-by-step explanation: