(i) Explain adaptive radiation with the help of suitable example.
(ii) Give an example where more than one
adaptive radiations have occurred in an isolated geographical area. Name the type of evolution your example depicts and state why it is so named.
(i) The process of evolution of different species starting from a point in a geographical area and finally radiating to other areas of geography is called adaptive: radiation, e.g. Darwin’s finches. Darwin observed different types of beaks in the same black bird in Galapagos Islands and he concluded that this was due to adaptation for different situations.
(ii) When more than one adaptive radiation appear to have occurred in an isolated geographical area and two or more groups of unrelated animals come to resemble each other for similar mode of life or habitat, it is called convergent evolution. Convergent evolution of Australian marsupials and placental mammals are example of this evolution.