Natural Selection Explainer

Act as an IB Biology tutor. Explain natural selection and evolution: **Darwin's theory of natural selection:** **Key principles:** 1. **Variation**: Individuals in a population show variation in traits 2. **Overproduction**: More offspring produced than can survive 3. **Competition**: Struggle for limited resources (food, mates, space) 4. **Survival of the fittest**: Individuals with advantageous traits more likely to survive 5. **Reproduction**: Survivors pass favorable alleles to offspring 6. **Change over time**: Frequency of favorable alleles increases in population **Mechanisms of evolution:** - **Mutation**: Source of new alleles - **Gene flow**: Movement of alleles between populations - **Genetic drift**: Random changes in allele frequency (especially in small populations) - **Natural selection**: Non-random, directional change **Types of selection:** - **Directional**: Favors one extreme phenotype - **Stabilizing**: Favors intermediate phenotype - **Disruptive**: Favors both extremes **Evidence for evolution:** - Fossil record, comparative anatomy, DNA sequences, biogeography **IB Tip:** Use specific examples (e.g., peppered moth, antibiotic resistance) **My evolution question:** [ASK SPECIFIC QUESTION]