Class 12th Biology 2017 Set3 Delhi Board Paper Solution
Explain the phenomenon that is well-represented by Darwin’s finches other than natural selection.
The phenomenon well-represented by Darwin’s finches other than natural selection is adaptive radiation.
Adaptive Radiation:
HF Osborn (1898) developed the concept of adaptive radiation or divergent evolution, i.e. the development of different functional structures from a common ancestral form.
When a group of organisms shares a homologous structure, which is specialised to perform a variety of different functions, it shows adaptive radiation . This represents the evolution of new forms in several directions from the common ancestral type (divergence).
The significance of adaptive radiation is that it suggests the existence of divergent evolution based on the modification of homologous structures.
The examples of divergent evolution are as follows:
(i) Darwin’s finches of Galapagos Islands has common ancestors. Later on, whose beaks modified according to their feeding habit.
(ii) Australian marsupials and limbs of mammals are also good examples of adaptive radiation.
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