UPSC Prelims 2011 · Question 36 of 100

UPSC Prelims 2011 question on Biodiversity Latitudinal Gradient

Consider the following statements:

1. Biodiversity is normally greater in the lower latitudes as compared to the higher latitudes.

2. Along the mountain gradients, biodiversity is normally greater in the lower altitudes as compared to the higher altitudes.

Which of the statements given above is/are correct?

  1. 1 only
  2. 2 only
  3. Both 1 and 2
  4. Neither 1 nor 2
Show answer

Answer: C. Both 1 and 2

Verdict

Correct Answer: Both 1 and 2

Both statements are correct because biodiversity generally decreases as we move from lower latitudes to higher latitudes and from lower altitudes to higher altitudes.

Statement by statement

1. Biodiversity is normally greater in lower latitudes than higher latitudes — Correct
Biodiversity is generally highest near the equator and decreases towards the poles. This is called the Latitudinal Diversity Gradient.

Tropical regions receive more sunlight, have higher productivity, stable climate and longer evolutionary time for species diversification.

2. Along mountain gradients, biodiversity is normally greater at lower altitudes than higher altitudes — Correct
Biodiversity usually decreases with altitude because higher altitudes have lower temperature, thinner air, lower oxygen, harsh winds and shorter growing seasons.

Lower altitudes provide warmer climate, better soil, more vegetation and larger habitats, supporting more species.

Extra UPSC info

India has four biodiversity hotspots: Himalayas, Western Ghats, Indo-Burma and Sundaland.
Alexander von Humboldt proposed the species-area relationship.
Species richness generally increases with area, up to a limit.
Biodiversity exists at three levels: genetic diversity, species diversity and ecosystem diversity.
Exceptions may occur, such as some species showing maximum diversity at middle elevations.

How to crack it

Biodiversity is normally greater in tropical lower latitudes and lower altitudes due to favourable climate, higher productivity and better habitat availability. Therefore, both statements are correct.

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