Describe one example of adaptive radiation.
Darwin's Finches represent one of the best examples of adaptive radiation. When Darwin visited the Galapagos Islands, he observed an amazing diversity of creatures, particularly small black birds later called Darwin's Finches.
From the original seed-eating features, many other forms with altered beaks arose, enabling them to become insectivorous and vegetarian finches. All these varieties evolved on the island itself.
This process of evolution of different species in a given geographical area starting from a point and literally radiating to other areas of geography (habitats) is called adaptive radiation.
Explanation
The question asks for one example of adaptive radiation worth 3 marks. Darwin's Finches from Galapagos Islands is the primary example given in NCERT. The answer covers: (1) the origin - ancestral seed-eating birds, (2) the diversification - altered beaks for different diets, and (3) the definition - radiating from one point to different habitats in the same geographical area. This example clearly illustrates how a single ancestral species can diversify into multiple species with different adaptations when exposed to varied environmental conditions.