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UPSC Prelims 2012 · Environment · Nature’s Machinery
Which of the following can be threats to the biodiversity of a geographical area? Select the correct answer using the codes given below:
- Global warming
- Fragmentation of habitat
- Invasion of alien species
- Promotion of vegetarianism
- (a) 1, 2 and 3 only
- (b) 2 and 3 only
- (c) 1 and 4 only
- (d) 1, 2, 3 and 4
Show the answer and explanation
Answer: (a) 1, 2 and 3 only
Global warming, fragmentation and invasive species are all recognised drivers of biodiversity loss.
Statement by statement
1. ✓ THREAT Warming shifts habitats faster than many species can move or adapt.
2. ✓ THREAT Breaking habitat into patches isolates populations and cuts gene flow.
3. ✓ THREAT Invasive species (Lantana, water hyacinth) out-compete natives.
4. ✗ NOT A THREAT Eating plants needs far less land than meat. It reduces pressure on habitats if anything.
The idea
Biologists speak of an “evil quartet” of causes of extinction: habitat loss and fragmentation, over-exploitation, invasion by alien species, and co-extinction (when one species dies out, those that depend on it follow). Climate change is now added as a fifth.
A road or farm cuts a forest into patches → Each patch holds a small, isolated population → Animals cannot meet and breed across patches → Small populations die out one by one
The trap
This one rewards common sense.
Also know
A classic invasion: the Nile perch put into Lake Victoria wiped out a large number of its native cichlid fish. A plant-based diet needs far less land than a meat-based one, so it eases pressure on habitats.
🔒 Main drivers of biodiversity loss (HIPPO): Habitat loss, Invasive species, Pollution, Population, Over-exploitation — plus climate change.