📝 Exam Summary: Human impact on biodiversity
Key Idea: Human activity is driving a sixth mass extinction, through both direct and indirect impacts.
⚠️ Threats to biodiversity
- Direct – overharvesting, poaching, the illegal pet trade
- Indirect – habitat loss & fragmentation, climate change, pollution, invasive alien species
- Tragedy of the commons – shared resources get overused by everyone
📋 IUCN Red List
- Ranks status from Least Concern → Extinct
- Criteria are about trends: population size & decline, geographic range, fragmentation, extinction probability
- Threats (poaching, dams…) are causes, not the criteria themselves
Tip: For an IUCN criterion use a directional word — 'declining population', not just 'population'. Invasive species harm natives by competition, predation and disease.