When considering pack territories, it must be remembered that typically speaking, the packs solely consist of werewolves. Because werecats are prone towards a more solitary life, they are not included in what is commonly construed of as "The Pack". Unlike vampire territories, they also tend to be more mercurial over time. This is often due to the fact that in the past, packs rose and fell as often as the sun rises and sets in the sky. Rexes came to power one day only to be deposed in the next. Thankfully, this trend has died off in more recent times. The social order of man has tamed some of the beast's more volatile behaviors.
REX - A pack is led by a Rex. He is the most alpha member of the pack as well as the final say in all matters. Though the Rex is not solely a male role, by law, it has only ever been held by a male due to what must be done to attain the position. When it has been decided that a Rex is no longer fit to hold the office, they will be challenged. Often times, all that is required is the death of the Rex. The honorable way to do this would be through a formal challenge presented during the pack meeting. The challenge does not need to end in death, though that is a common outcome. There are times that the winner of fight can banish the other, regardless of whether they are the challenger or Rex. As long as they are the winner, they alone hold the life of the other in their hands.
If the Rex dies, not at the hand of a formal challenge, but rather of natural causes or more malicious ones, volunteers will be heard. The beta automatically becomes Regent Rex until a new one can be selected. Should the Beta be selected as the new Rex, he may then select his own Beta.
BETA - The Beta is the second most high position that a were can hold. They are the right hand of the Rex. Their sole responsibility is to support and protect their Rex with their lives if necessary. They often times take over the day to day running of the pack, collecting reports, news, and doling out the Rex's justice as he has been instructed.
The position of Beta cannot be inherited or won. They are only ever appointed by the currently seated Rex. When a new Rex is appointed they are either accepted as Beta, or replaced by whomever the Rex sees fit. They do not have to die to lose their position as they can be replaced without any repercussions.