Topic 3.2 covers the mechanisms of evolution through natural selection, genetic variation, and speciation. Students study how populations change over time, the role of geographic isolation, and how new species form — connecting biological theory to conservation.
Key Idea: Biodiversity exists because species change over time. This is called {{evolution|Gradual change in inherited traits over generations.}} — it's why we have so many different species!
Always use this order: variation → selection → reproduction → inheritance
Evolution happens to populations, not individuals. Nature picks what survives, not what's "best".
ESS is assessed through Paper 1 (case study) and Paper 2 (short answer & structured questions). Concepts from this topic may appear in either paper, often combined with data analysis or real-world examples.
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Start studying freeTopic 3.2 Natural selection, variation and speciation forms a core part of Unit 3: Biodiversity and Conservation in IB ESS. Mastering these concepts will strengthen your understanding of connected topics across the syllabus and prepare you for exam questions that require analysis, evaluation, and real-world application.
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