That position should be mine after all you do to us
Buck, a trained half St. Bernard and half German Shepard, gets captured by the gardener, Manuel, and then he is sent to Canada to be part of a sled team . While he is being taken to Canada, he gets hit by a club a few couple times, which gives him the idea of the law of club. This represents survival of the fittest because this is how he learns to obey his master or else he would be beaten.
Dave Gets Killed
Buck, Francois, Perrault, and the rest of the sled dogs get raided by a group of ravenous huskies that try to steal all the food and kill the sled dogs. Curly also tries to stand strong like Buck but she gets killed. The relates to survival of the fittest because Buck learns not to fall in a fight, as stated in page 15.
Buck finally fights Spitz for the leadership position that Spitz is in possession of so far. Buck also wants to end the rivalry they are in since Curly's death. But Spitz thinks that he can kill Buck and win the fight. This connects to survival of the fittest because they are fighting for their lives, as it is stated in part of the book's theme.
Dave has been badly injured during a fight by a husky that had tried to kill him, which meant Dave couldn't be able to help out in the team, which made him bite the sled traces off since he was mad. But since he couldn't help out, he was killed off by a revolver. This relates to survival of the fittest because only the fittest and most skillful can survive, as stated on page 51.
Now the native Americans tell of an evil spirit that has terrorized them, and every night for once a year, the spirit goes to a specific location and howls. However, when the native Americans look for where its coming from, he isn't seen, which gave him the title of "The Ghost Dog." This relates to survival of the fittest because because The Ghost Dog is Buck but it is after he joined the wolf pack on page 104-105.