Q.Explain latitudinal gradient pattern of biodiversity.

Latitudinal Gradient in Biodiversity

If you walk from the North Pole toward the equator, the number of species around you steadily increases. A tropical rainforest in the Amazon holds thousands of tree species in a small area, while a boreal or Arctic region may have only a handful. This consistent, worldwide pattern — species diversity generally increases as you move from the poles towards the equator — is called the latitudinal gradient in diversity, and it is one of the most striking, best-documented patterns in ecology.

The pattern

Tropical latitudes (roughly 23.5° N to 23.5° S) harbour more species than temperate regions, which in turn hold more than polar regions. The Amazonian rainforest is the single most species-rich place on Earth. The question that has fascinated ecologists is not whether this happens but why.

Why the tropics are so rich — the leading hypotheses

• More evolutionary time: Tropical regions have remained relatively undisturbed for long periods, whereas temperate regions faced repeated glaciations. More time allowed more speciation.
• Constant, favourable climate: The tropics have a warm, stable environment that promotes niche specialisation — species can afford to be specialists, so more species pack into the same space.
• Greater solar energy: More incoming sunlight supports higher productivity, which contributes to greater diversity. …