# Species > **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:** Evolution / Systematics **Doc Type:** Canonical Wiki Node **Maturity:** Developed ## Definition A species is an independently evolving lineage or population grouping identified through reproductive, ecological, genetic or phylogenetic criteria. ## Nexus Context The concept helps assess whether digital divergence constitutes more than variant instances. Barricelli reported species-like separation; blockchain forks are better treated as technical lineages unless reproductive criteria are mapped. ## Evidence Boundary No single species concept fits every biological or artificial case. The criterion used must be stated. ## Relationships [[wiki/Speciation|Speciation]], [[wiki/Lineage|Lineage]], [[wiki/Digital Population|Digital Population]], [[wiki/Branching Descent|Branching Descent]] ## Sources / Provenance - De Queiroz’s unified species concept; systematics literature.