ncert books class 12 biology chapter 13 · Section 1

If an alien from a distant galaxy were to visit our planet Earth, the first thing that would amaze and baffle him would most probably be the enormous diversity of life that he would encounter. Even for humans, the rich variety of living organisms with which they share this planet never ceases to astonish and fascinate us. The common man would find it hard to believe that there are more than , species of ants, , , species of beetles, , species of fishes and nearly , species of orchids. Ecologists and evolutionary biologists have been trying to understand the significance of such diversity by asking important questions– Why are there so many species?

Did such great diversity exist throughout earth’s history? How did this diversification come about? How and why is this diversity important to the biosphere? Would it function any differently if the diversity was much less?

How do humans benefit from the diversity of life?