Territorialism

Territory is the sociographical area that a creature of a particular species consistently defends against conspecifics (or, occasionally, creatures of other species). Creatures that defend territories in this way are referred to as territorial.
The ultimate function of creatures inhabiting and defending a territory is to increase the individual fitness or inclusive fitness of the creatures expressing the behaviour. Fitness in this biological sense relates to the ability of a creature to survive and raise young. The proximate functions of territory defense vary. For some creatures, the reason for such protective behaviour is to acquire and protect food sources, nesting sites, mating areas, or to attract a mate.
Rather than retaining a territory simply by fighting, for some animals this can be a 3-stage process. Many animals create "sign-posts" to advertise their territory. Sometimes these sign-posts are on the boundary thereby demarcating the territory, or, may be scattered throughout the territory. These communicate to other animals that the territory is occupied and may also communicate additional information such as the sex, reproductive status or dominance status of the territory-holder. Sign-posts may communicate information by olfactory, auditory, or visual means, or a combination of these. If an intruder progresses further into the territory beyond the sign-posts and encounters the territory-holder, both animals may begin ritualized aggression toward each other. (See: Communication; Language.)
In ethics, territorialism is an ethical principle that says that one should give greater moral weight to the interests and preferences of those who are within the boundaries of one's geographical region than those outside. It is a slight variation on citizenism. 
 There's a war goin' on outside no man is safe from
 You could run but you can't hide forever
 From these streets that we done took
 You walkin' witcha head down scared to look
 You shook 'cause ain't no such things as halfway crooks
 They never around when the beef cooks in my part of town
 It's similar to Vietnam
 Now we all grown up and old, and beyond the cop's control [Mobb Deep, 1995]
== Rhizomata ==
Hypergame; Competition; Territorialisation
Predation