Class 12 Biology Evolution Adaptive radiation

Adaptive radiation

The evolution of different species in a given geographical area starting from its original character and radiating to other geographical area is called adaptive radiation. Examples-

Finches in Galapagos island-

  • During Darwin’s journey to Galapagos Island he observed small black birds called Darwin’s Finches.
  • The finches were diverse in their food habitats like original from seeds eating features to many other forms with altered beaks arose enabling them to become insectivorous and vegetarian finches.

Fig. Darwin’s finches  

Australian marsupials

  • A number of marsupials, each different from the other evolved from an ancestral stock but all within the Australian continent.

Examples- Tasmanian wolf, tiger cat, marsupial rat, kangaroo, wombat, sugar glider etc.

            

    Fig. tiger cat            

     Fig. kangaroo

 

Placental mammals-

  • In Australia adaptive radiation is exhibited where placental mammals are evolved into varieties each of which appears to be similar to a corresponding marsupials.

Example- placental wolf and Tasmanian wolf marsupial.

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