A single individual defends an area against all others of the same sex and species. Several individuals join together to defend the territory against other of the same, or of other species. Territories provide a valuable resource, such as food, nesting sites or shelter, to the residents that allows them to survive and reproduce. To determine if one appears dominant over the other, and if so, to identify the dominant behaviors. Dominance status may represent an adaptation.
Dominant individuals have priority of access to important resources.
Characteristics that are associated with success in dominance interactions would thus be favored in natural selection because dominant individuals would survive and subsequently reproduce more often than subordinate individuals. Territoriality occurs primarily because territorial individuals survive and reproduce better than non-territorial ones.