2.1.23—Keystone species
- Syllabus
- First assessment 2026
- Objective
- 2.1.23
- Level
- SL
Test Removal for a Keystone Effect
A keystone species has an effect on community structure much larger than its abundance would suggest.
Ask what changes when the species is removed: trophic control or habitat engineering can reorganize many other populations.
Sea stars limit mussel dominance and retain intertidal diversity; elephants remove woody vegetation and maintain grassland patches.
No. Test the disproportionate consequence of removal.
Keystone status is about effect size, not body size or abundance.