Question

1. Explain the theory of evolution with examples.

2. How can we measure evolutionary process in populations that are still in existance.

3. What are different forces that cause evolution. (Explain how each works and how the forces are different)

Answer 1

Example -

1. Theory of evolution with examples=

There are 4 main theories of evolution:

1] Lamarckism or theory of Inheritance of Acquired characters.= It is called " Theory of Inheritance of Acquired characters."and was proposed by great french naturalist ,Jean BAptiste de Lamarck.

This theory is based on the inheriatance of acquired characters which are defined as changes (variation) developed in the body of an organism from normal characters,in response to the changes in the environment or in the functioning of organs ,in their own life time,to fulfill their new needs.

Postulates of Lamarckism-

1.New needs

2.Use and disues of organs.

3.Inheritance of aquired characters.

4.Speciation

Example- Development of present day long -necked and long fore-necked giraffe from deer-like ancestor by the gradual elongation of neck and forelimbs in response to deficiency of food on the barren ground in dry deserts of Africa.

2] Darwinism(Theory of Natural selection) = Main postulates are

-Geometric increase

- Limited food & space .

- Struggle for existance.

- Variations.

- Natural selection or survival of the fittest.

- Inheritance of useful variations.

-Speciation.

example- Correlation between position of nectaries in the flowers and length of the proboscis of the pollinating insects.