Grade 11 · Biology
Natural selection
Why it matters
Variation, fitness and how populations change over time.
Core20m readingPrerequisite: Evidence for evolution
What is natural selection?
Short answer
Natural selection is the process by which heritable traits that improve survival and reproduction become more common in a population over generations. Individuals vary; some variations give a reproductive advantage in a given environment, so those individuals leave more offspring. Over time this shifts the population’s traits — the core mechanism of evolution described by Darwin.
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Frequently asked questions
- What are the requirements for natural selection?
- Variation in traits, heritability of those traits, and differential survival or reproduction based on them.
- Is natural selection the same as evolution?
- No. Natural selection is one mechanism that causes evolution — the change in a population’s allele frequencies over time.