Natural selection
Heritable variation can change through differences in reproductive contribution.
Key knowledge
Natural selection occurs when heritable differences affect organisms' contributions to later generations. Variants associated with greater reproductive contribution in the relevant environment can become more frequent, producing adaptation under suitable conditions.
Conditions and scope
- Requires heritable variation and differences in reproductive contribution; survival alone is not the definition of fitness.
- The outcome depends on environment, tradeoffs and available variation, and need not produce a perfect organism.
Sources · 2
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Source-documented account of relative fitness, selection and constraints; no selection experiment was recreated.
2026-10-10 · English mechanism checked against Adaptive Evolution's opening account and No Perfect Organism section; deterministic fixation is not asserted.
Foundational review
2026-10-10 · Fresh primary-source inspection of the complete compact record, including every statement, equation, quantity and material condition, followed by independent AI editorial review. This check does not certify all linked lessons or every passage of every cited publication.
Sources from other places
Agreement within this scope
Heritable differences and environment-dependent reproductive contribution.
Reproductive contribution matters, not survival alone.
NCERT
- Biology XII: Evolution IndiaEnglish
§6.3, printed pp113–115: homology and common ancestry; §6.5, printed p118: branching descent and heritable fitness; §6.7, printed pp120–121: allele-frequency changes and chance drift
- Biology XII: Evolution
Entry details
Permanent link to this entry ↗- Record identity
- bio-natural-selection
- Revision
- core.1
- Structured reference record
- Essential core · first collection