Philopatric species that do not migrate may evolve to breed cooperatively. Kin selection, of which cooperative breeding is a form, explains how individual offspring provide care for further offspring produced by their relatives. Animals that are philopatric to birthsites have increased association with family members, and, in situations where inclusive fitness is increased through cooperative breeding, may evolve such behaviour, as it will incur evolutionary benefits to families that do. Inclusive fitness is the sum of all direct and indirect fitness, where direct fitness is defined as the amount of fitness gained through producing offspring. Indirect fitness is defined as the amount of fitness gained through aiding related individuals offspring.