3.1.5—Natural selection process HL
- Syllabus
- First assessment 2026
- Objective
- 3.1.5
- Level
- HL
Build the Natural-Selection Chain
Heritable variation plus overproduction, competition and differential reproduction can change a population over generations.
Resources limit survival. Individuals with traits better suited to current conditions tend, on average, to leave more offspring, so their alleles become more common.
If drought kills more shallow-rooted plants, deep-rooted heritable variants may contribute more seeds next season.
Selection changes reproductive contribution; population frequency shifts accumulate across generations.
‘Survival of the fittest’ means reproductive success in context, not physical strength alone.