Biology · Evolution · NEET
They are linked but not identical. Adaptive radiation is the pattern: one ancestral stock gives rise to many species that spread into different habitats in one geographical area. At the level of structure, this is divergent evolution — the same body plan changes along different directions. So Darwin's finches show adaptive radiation, and their beaks are a case of divergent evolution. For NEET, remember: adaptive radiation is the big-picture process, divergence is the structural mechanism behind it.
Natural selection is the tool that shapes each population. Adaptive radiation is the overall result when that tool acts on ONE ancestor spreading into MANY vacant habitats, producing many new species. Every case of adaptive radiation uses natural selection, but not every natural selection event produces radiation. NTA has asked both — read the option that best names the whole pattern (adaptive radiation) versus the mechanism (natural selection).
The original finches were seed-eaters. On the Galapagos Islands there were many empty (vacant) habitats with different food sources. Different food types favoured different beak shapes — seed-crushing, insect-eating, etc. Over generations, natural selection acting on each food niche produced distinct beak forms. This is why NCERT stresses that adaptive radiation needs MANY vacant habitats to fill.
Adaptive radiation is DIVERGENT — one stock diverging into many forms. Do not confuse it with convergent evolution. Convergent evolution is when UNRELATED groups (like Australian marsupials and placental mammals) independently evolve similar features. When more than one adaptive radiation appears to have occurred in an isolated area, the SIMILARITY between the two separate radiations is called convergent evolution. That subtle line is a favourite NEET trap.
Charles Darwin observed them on the Galapagos Islands (in the Pacific Ocean) during his voyage on HMS Beagle. He saw small black birds, later called Darwin's finches, that had all diversified from one seed-eating ancestor. Australian marsupials are the second NCERT example of adaptive radiation.
A population of a species invades a new area. Which of the following condition will lead to Adaptive Radiation?
Select the correct group/set of Australian Marsupials exhibiting adaptive radiation.
Match List I with List II. (a) Adaptive radiation (b) Convergent evolution (c) Divergent evolution (d) Evolution by anthropogenic action, with (i) resistant varieties from herbicides/pesticides (ii) forelimb bones in Man and Whale (iii) wings of butterfly and birds (iv) Darwin Finches.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
It is the evolution of many different species from one ancestral stock, starting from a point and radiating into different habitats of a geographical area, as seen in Darwin's finches.
Charles Darwin observed them on the Galapagos Islands during his voyage on HMS Beagle. They evolved from a single seed-eating ancestor into finches with many beak types.
Darwin's finches of the Galapagos Islands and the Australian marsupials. Both show many species arising from one ancestral stock in an isolated area.
It is divergent evolution — one stock diverging into many forms. Convergent evolution is when two unrelated groups become similar, like Australian marsupials and placental mammals.
The Galapagos Islands offered many vacant habitats with different foods. Natural selection favoured different beak shapes suited to seeds, insects and other foods, so distinct species formed.
