Question

Species diversity decreases as we move away from the equator towards the poles. What could be the possible reasons?

Answer 1

Species diversity decreases from the equator towards the poles

Species diversity increases as we move from the poles towards the equator. The tropical regions (ranging from ${23.5}^{\circ }$N to ${23.5}^{\circ }$S) have more variety in availability of species than the polar or temperate (${23.5}^{\circ }$N to ${66.5}^{\circ }$N and ${23.5}^{\circ }$S to ${66.5}^{\circ }$S) regions.
India, which majorly lies in the tropical zone, has 1200 different species of birds where Greenland at ${71}^{\circ }$N has only 56 different species of birds.



Reasons

• Temperature decreases as we move away from the equator towards the poles due to the tilt of the Earth's axis. Many organisms that do not have the ability to regulate their body temperatures cannot survive in the low temperature regions.
• Due to unavailability of sunlight, most plant species are not able to survive, perform photosynthesis and produce food. Availability of lesser solar radiation leads to reduced productivity which indirectly contributes to lesser diversity. Most of the species are not able to survive as they are dependent on plants for food.
• Moreover, towards poles the seasonal variations increase which does not provide much time for species diversification.