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UPSC Prelims 1981 · Environment · Nature’s Machinery
When a person moves from poles to the equator, the population of plants and animals will
- (a) Increase
- (b) Decrease
- (c) Remain unchanged
- (d) Not show any consistent behaviour
Show the answer and explanation
Answer: (a) Increase
More sunlight, warmth and stable climate towards the equator → more species of plants and animals.
The idea
The question uses “population” loosely for the variety and amount of life. Both rise towards the equator, because warmth, sunlight and a year-round growing season let more plants grow, and more plants feed more animals.
Polar ice: almost no plants → Tundra: mosses and lichens → Taiga: a few kinds of conifer → Temperate forest: more kinds → Tropical forest: the most
Why the others are wrong
(b) That is the reverse of the gradient.
(d) The latitudinal gradient is one of the most consistent patterns in ecology.
Also know
This pattern is called the latitudinal diversity gradient. A single hectare of tropical forest can hold more tree species than the whole of a cold northern country.
🔒 Species diversity increases from the poles to the equator.