Biology · Continuity and change

D4.1 — Natural selection

Biology · SL / HL · syllabus-mapped notes

1. D4.1.1

   Natural selection as the mechanism driving evolutionary change

   Explain the four statements that make up the theory of evolution by natural selection.

2. D4.1.2

   Roles of mutation and sexual reproduction in generating the variation on which natural selection acts

   Explain how mutation and sexual reproduction generate the variation selection acts on.

3. D4.1.3

   Overproduction of offspring and competition for resources as factors that promote natural selection

   Explain how overproduction of offspring and competition promote natural selection.

4. D4.1.4

   Abiotic factors as selection pressures

   Explain how abiotic factors act as selection pressures.

5. D4.1.5

   Differences between individuals in adaptation, survival and reproduction as the basis for natural selection

   Explain how differences in adaptation affect survival and reproduction.

6. D4.1.6

   Requirement that traits are heritable for evolutionary change to occur

   Explain why acquired traits cannot be inherited, and so cannot drive evolution.

7. D4.1.7

   Sexual selection as a selection pressure in animal species

   Explain sexual selection, and why costly traits can persist.

8. D4.1.8

   Modelling of sexual and natural selection based on experimental control of selection pressures

   Model selection experimentally by controlling the selection pressure.

9. D4.1.9

   Concept of the gene pool

   Define gene pool and allele frequency.

10. D4.1.10

    Allele frequencies of geographically isolated populations

    Explain why geographically isolated populations differ in allele frequency.

11. D4.1.11

    Changes in allele frequency in the gene pool as a consequence of natural selection between individuals according to differences in their heritable traits

    Explain why only a change in allele frequency counts as evolution.

12. D4.1.12

    Differences between directional, disruptive and stabilizing selection

    Contrast stabilizing, disruptive and directional selection, with an example of each.

13. D4.1.13

    Hardy–Weinberg equation and calculations of allele or genotype frequencies

    Use the Hardy-Weinberg equation to calculate allele and genotype frequencies.

14. D4.1.14

    Hardy–Weinberg conditions that must be maintained for a population to be in genetic equilibrium

    State the five conditions for genetic equilibrium, and how departures detect evolution.

15. D4.1.15

    Artificial selection by deliberate choice of traits

    Explain artificial selection, and why improvement slows over generations.