Bucks feet started hurting so Francois picked up Buck. This showed survival of the fittest because if Francois didn do that then Buck would´ve hurt his feet.
Spitz shows survival of the fittest because to me it seems like Spitz is the one who can adapt to the snow and climate the most because of his thick fur and size.
Mercedes shows survival of the fittest because she was not able to adapt to the cold climate and had zero expierence. She also would always whine.
The fight shows survival of the fittest because Buck and Spitz fought about the rabbit. They were so hungry that they all fought over a rabbit. This shows survival of the fittest because they couldn´t adapt to how much food they got and were really hungry.
In this scene it shows Buck deciplining the dogs. This shows survival of the fittest because the dogs adapted to Buck being the leader and decipling them .
This scene shows the dogs sleeping. This shows survival of the fittest because they adapted to the cold while they were sleeping,and learned how to burry themselves i the snow to keep warm.