Theme - "Call of the Wild"
Adaptability is a key part in "The Call of the Wild." One way adaptability is shown is when Buck notices the pads of his feet were hardening. He was adapting to the frozen ground. Buck also adapted by learning new skills quickly. For example Francois says in chapter 2, "Dat Buck, him pull like hell. I teach him quick as anything." He also quickly learned how to keep warm when he slept. Buck quickly gained the strength he needed to survive in the Yukon as well. In chapter 6 it said "...where the muscles showed in tight rolls underneath the skin." Adaptability was shown throughout the rest of the story in various places.
Adaptability is a huge part of the story for the reasons listed above and more. Without adapting the climate Buck never could of survived. That is why adaptability is a key role in the story.