UPSC Prelims 2012 Q96: Environment & Ecology – Biodiversity & Conservation
Which of the following can be threats to the biodiversity of a geographical area?
1. Global warming
2. Fragmentation of habitat
3. Invasion of alien species
4. Promotion of vegetarianism
Select the correct answer using the codes given below :
- (a) 1, 2 and 3 only
- (b) 2 and 3 only
- (c) 1 and 4 only
- (d) 1, 2, 3 and 4
Answer: (a) 1, 2 and 3 only
Explanation
Threats to biodiversity
| Factor | A threat? | Reason |
|---|---|---|
| 1. Global warming | Yes | Shifts climate zones; species that cannot move or adapt die out |
| 2. Fragmentation of habitat | Yes | Breaks large habitats into small patches; the biggest cause of loss |
| 3. Invasion of alien species | Yes | Outsiders such as lantana, water hyacinth and Nile perch crowd out natives |
| 4. Promotion of vegetarianism | No | It does not harm wild species |
The 'Evil Quartet' of biodiversity loss:
| Cause | Example |
|---|---|
| Habitat loss and fragmentation | Clearing of the Amazon rainforest |
| Over-exploitation | Steller's sea cow, passenger pigeon |
| Alien species invasions | Nile perch in Lake Victoria |
| Co-extinctions | A parasite dying with its host |
Answer: (a) 1, 2 and 3 only.
Why each option is right or wrong
- (a) CORRECT. Global warming, fragmentation of habitat and alien species are threats.
- (b) Incorrect. Global warming is also a threat to biodiversity.
- (c) Incorrect. Promotion of vegetarianism is no threat, and Statements 2 and 3 are left out.
- (d) Incorrect. Promotion of vegetarianism does not threaten biodiversity.
Key point
Biodiversity loss: habitat loss and fragmentation, over-exploitation, alien species, co-extinction (the Evil Quartet), plus climate change and pollution.
Remember
Evil Quartet: habitat loss, over-use, aliens, co-extinction.
Common mistakes
- Over-thinking the vegetarianism statement into a land-use argument.
- Forgetting alien species such as lantana and water hyacinth.
- Ranking climate change above habitat loss, which is still the main cause.
Exam tip
One item in the list is there only to tempt over-thinkers. Vegetarianism is harmless to wildlife.
Sources
- NCERT Class XII — Biology, Ch 15 (Biodiversity and Conservation)
- Convention on Biological Diversity — Global Biodiversity Outlook