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  1. Progressive change in structure and anatomy of organisms.
  2. Structural adaptation: Adaptive colouration.
  3. Structural adaptation: For obtaining food.
  4. Different castes of termites.
  5. Different castes of bees.




Definition of Evolution

Organic evolution is the sum total of adaptive changes that have taken place over a long period of time in the life history of an organism. This process usually leads to the development of new species from pre-existing ones.

Organic evolution suggests that all living things have arisen from pre-existing ones by a gradual process of change over a long period of time.

Evolution proposes that life started in water; from marine water to fresh water to land and then to air. Progressive changes in the structure and anatomy of organisms have been going on as they inhabited these habitats at one time or the other. These changes enabled the organisms to be well adapted to the various habitats.

Organisms that live in water environment have streamlined body shape, soft and moist skin, water dependent reproductive system, efficient osmoregulator and other structural and anatomical adaptations.

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