# Competition > **Machine-Evolution Nexus:** [[articles/Digital Darwinism and the Invisible World of Machine Evolution|Digital Darwinism and the Invisible World of Machine Evolution]] places this concept within the history and governance of substrate-independent evolution. **Domain:** Ecology / Selection **Doc Type:** Canonical Wiki Node **Maturity:** Developed ## Definition Competition occurs when entities reduce one another’s access to scarce resources, opportunities or reproduction. ## Machine-Evolution Context Space in Evoloops and CPU time or memory in Tierra and Avida convert coexistence into differential persistence. Competition can therefore supply part of a selection environment. ## Continuity and Evidence Boundary Not every comparison or market rivalry is Darwinian competition. The population, scarcity mechanism, heritable differences and reproductive consequences must be identified. ## Relationships [[wiki/Resource Constraint|Resource Constraint]], [[wiki/Differential Reproductive Success|Differential Reproductive Success]], [[wiki/Competitive Exclusion|Competitive Exclusion]], [[wiki/Artificial Ecology|Artificial Ecology]] ## Sources / Provenance - Ecology texts; digital-evolution literature.