They occur when the individuals are of the same species. There are four types:
-Family associations: They are composed by individuals who are related to one another. Example: Cheetah family.
-Gregarious associations: They are formed by individuals, that come together fo a specific purpose, and not necessarily related to each one. Example: Mussels fixed to a rock.
-Social associations: The individuals form a hierarchy. Example: Partridgres.
-Colonial associations: The individuals have the same progenitor. Example: Ñu.
They occur between organisms of different species. There are a lot of examples, but the most important are:
-Interspecific competition: It is a relationship between the same specie. Example: Lions and hyenas.
-Predation: This occurs among a predator, which captures another, which is the prey. Example: Cheetahs and gazzelles.
-Parasitism: It benefits to the parasite, which feeds on without killing the host. Example: Dog and flea.
-Mutualisim: In this relationship, both species benefit. Example: Clown fish and sea anemone.
-Commensalism: It benefits one specie and does not affect the other. Example: Anemones that use mussel shells.
Another examples of these relationships are symbiosis, thanatocresis...