Territory is an area guarded against intrusion by conspecifics, usually to protect access to food, shelter, or mates. Territories are marked with displays, scents, sounds, or gestures. Often these are in the form of ritualistic aggression. Often, both partners must display until both are convinced that no harm will come to them if they get close enough to mate. This happens among at least some mammals even if they are given plenty of food and water, and clean living conditions.
Dominance leads to more food and better mates, which results in more offspring.