Explain how artificial selection differs from natural selection in the mechanism by which heritable variation is passed to subsequent generations, using a named domesticated species as an example.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
In natural selection, individuals with advantageous heritable traits survive and reproduce at higher rates because of environmental pressures. In artificial selection, humans deliberately choose which individuals breed based on desired traits, acting as the selecting agent instead of the environment. In both cases, the selected traits are heritable, so the favoured alleles are passed to offspring, increasing their frequency in subsequent generations. For example, dogs (Canis lupus familiaris) have been selectively bred for different coat types and body sizes.
Examiner tips
- Use the word ‘selective breeding’ for artificial selection; mention the human agent explicitly.
- Show that the traits are heritable and that offspring inherit them, linking to increased frequency.
- Give a clear example of a domesticated species and a specific trait that has been selected.
Common mistakes
- Confusing natural and artificial selection by saying humans act as the environment.
- Failing to state that the traits are heritable and that offspring inherit them.
- Using a non‑domesticated species or an irrelevant example.
Mark scheme (4 marks)
- In natural selection, individuals with advantageous heritable traits survive and reproduce at higher rates due to selection pressures in the environment.
- In artificial selection, humans deliberately choose which individuals breed based on desired traits, acting as the selecting agent instead of environmental pressures.
- In both cases, the selected traits are heritable, so offspring inherit the favoured alleles/traits, increasing their frequency in subsequent generations.
- Named domesticated species used correctly as an example, e.g. dogs (Canis lupus familiaris) selectively bred for body size or coat type; cattle bred for increased milk yield; wheat bred for larger grain size.
Key terms in this question
artificial selection · natural selection · heritable variation
Related
- All IB DP Biology Standard Level (2023 syllabus) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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