How does Buck create mutiny among the team of dogs in Call of the Wild?

Buck creates mutiny among the team of dogs by undermining the authority of Spitz, the leader of the pack.

It is in Buck's nature to lead, and an open enmity develops between him and Spitz, the "lead-dog and acknowledged master of the team".  Buck takes every opportunity to interfere when Spitz tries to discipline "shirks" among the dogs.  For example, when Pike, a notorious malingerer, does not appear one morning, Spitz is "wild with wrath".  When he finally unearths the dog, he flies at him to punish him, but Buck, "with equal rage", puts himself in between.  Francois, the driver, must subdue Buck with his lash so that Spitz can do his job and discipline the offender.

In the following days, Buck continues to interfere between Spitz and the team.  With "the covert mutiny of Buck, a general insubordination (springs) up and increase(s)" among the dogs.  There is "continual bickering and jangling" on the team that previously, under Spitz's leadership, had operated smoothly as a unit -

"The insidious revolt led by Buck had destroyed the solidarity of the team.  It no longer was as one dog leaping in the traces.  The encouragement Buck gave the rebels led them into all kinds of petty misdemeanors.  No more was Spitz a leader greatly to be feared.  The old awe departed, and they grew equal to challenging his authority" (Chapter 3).