# Parasite > **Machine-Evolution Nexus:** [[articles/Digital Darwinism and the Invisible World of Machine Evolution|Digital Darwinism and the Invisible World of Machine Evolution]] places this node within the history and governance of substrate-independent evolution. **Domain:** Ecology / Digital Evolution **Doc Type:** Canonical Wiki Node **Maturity:** Developed ## Definition A parasite is an organism or digital lineage that exploits a host’s resources or machinery to support its own reproduction. ## Nexus Context Tierra’s evolved parasites omitted portions of their replication machinery and used code in nearby hosts, gaining efficiency while imposing a selective burden. ## Evidence Boundary The term names a functional ecological relation. It does not imply intention, malice or subjective experience. ## Relationships [[wiki/Parasitism|Parasitism]], [[wiki/Host-Parasite Coevolution|Host-Parasite Coevolution]], [[wiki/Hyperparasite|Hyperparasite]], [[wiki/Tierra|Tierra]] ## Sources / Provenance - Ray (1991); digital-evolution literature.