Biology · Biodiversity and Conservation · NEET
It is a pattern in nature. As you move away from the equator toward the North Pole or South Pole, the number of species living in a region slowly goes down. NCERT calls this the most well-known pattern of biodiversity. So the equator is the richest belt, and the poles are the poorest.
The tropics run from 23.5 degrees North to 23.5 degrees South of the equator. NCERT states this exact range, so remember the number 23.5. Any region inside this belt is called tropical, and these regions harbour more species than temperate or polar regions.
It decreases. Species diversity is maximum at the equator and drops steadily toward the poles. Students often flip this in the exam. Just fix in your mind: equator = high, poles = low.
The tropical Amazon rain forest in South America. It follows the latitudinal gradient because it sits near the equator. NCERT names it as having the greatest biodiversity on Earth, with more than 40,000 plant species, over 1,25,000 invertebrates, and thousands of birds, fishes and mammals.
Yes, but very few. NCERT says with very few exceptions, tropics harbour more species than temperate or polar regions. So the pattern is a general trend, not a strict law. In an exam answer, use the word general or the phrase with very few exceptions.
Both are patterns of biodiversity. Latitudinal means diversity changes as you move across latitudes (equator to poles). Altitudinal means diversity changes as you climb up a mountain (higher altitude = fewer species). In both cases, moving toward a colder, harsher place lowers diversity.
Which of the following regions of the globe exhibits highest species diversity?
Arrange the following in descending order of the number of species in the Amazonian rain forest: (a) Plants, (b) Birds, (c) Fishes, (d) Invertebrates, (e) Mammals.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
It is the trend that regions near the equator have many species, and the number of species goes down as you move toward the poles. The tropics are the richest, the poles are the poorest.
NCERT gives three hypotheses: tropics had a longer, undisturbed evolutionary time for species to form; tropical climate is more constant and predictable, which helps niche specialisation; and more solar energy in the tropics gives higher productivity. These reasons are covered in detail on the hypotheses page.
From 23.5 degrees North to 23.5 degrees South of the equator. Remember this exact figure for one-mark NEET questions.
No, it is a general pattern. NCERT says with very few exceptions, tropics harbour more species than temperate or polar regions. Use the word general in your answers.
The tropical Amazon rain forest in South America, because it lies near the equator, the richest zone of the latitudinal gradient.
