UPSC Prelims 2011 Q24: Environment & Ecology – Biodiversity & Conservation
The Himalayan Range is very rich in species diversity. Which one among the following is the
most appropriate reason for this phenomenon?
- (a) It has a high rainfall that supports luxuriant vegetative growth
- (b) It is a confluence of different bio - geographical zones
- (c) Exotic and invasive species have not been introduced in this region
- (d) It has less human interference
Answer: (b) It is a confluence of different bio - geographical zones
Explanation
Why the Himalaya is so species-rich
| Option | Verdict | Reason |
|---|---|---|
| (a) High rainfall supports luxuriant vegetation | Incorrect | Rainfall varies hugely across the Himalaya (wet east, dry west); it alone cannot explain the overall richness |
| (b) Confluence of different bio-geographical zones | Correct | The Himalaya is where Palearctic, Indo-Malayan and Indo-Chinese biogeographic realms meet, mixing species from very different climatic and evolutionary origins |
| (c) Exotic/invasive species have not been introduced | Incorrect | The Himalaya does have introduced species; this is not the reason for its native richness |
| (d) Less human interference | Incorrect | Many Himalayan areas face significant human pressure; this does not explain the fundamental richness |
Why 'confluence of biogeographic zones' matters:
| Zone meeting at the Himalaya | Brings in |
|---|---|
| Palearctic (northern, temperate) | Cold-adapted flora and fauna |
| Indo-Malayan (tropical Asia) | Tropical, humid-forest species |
| Altitude gradient | Tropical to alpine zones in a short horizontal distance, multiplying habitat types |
Answer: (b) It is a confluence of different bio-geographical zones.
Why each option is right or wrong
- (a) Incorrect. Rainfall varies widely across the range and cannot alone explain uniform species richness.
- (b) CORRECT. The Himalaya sits at the meeting point of several biogeographic zones, mixing species pools.
- (c) Incorrect. Exotic species have been introduced in the Himalaya; their absence is not the real reason.
- (d) Incorrect. Human interference exists in many Himalayan areas; low interference is not the primary explanation.
Key point
Himalayan species richness: the range is a confluence of different biogeographic zones (Palearctic, Indo-Malayan etc.), compressed over a steep altitude gradient from tropical to alpine.
Remember
Himalaya richness = confluence of biogeographic zones.
Common mistakes
- Over-crediting rainfall alone, when the range's climate is actually very varied.
- Assuming richness means the area is untouched by humans or invasive species.
- Missing the specific term 'biogeographic confluence', a frequently tested phrase.
Exam tip
'Confluence of biogeographic zones' is the standard explanation whenever a region's richness comes from mixing distinct faunal/floral realms.
Sources
- NCERT Class XII Biology — Biodiversity and Conservation
- Ministry of Environment and Forests, Government of India — India's Fourth National Report to the Convention on Biological Diversity (2009)