1. S.Banerjee (Krishti Education)
EVOLUTION
S.Banerjee (Krishti Education)

2. S.Banerjee (Krishti Education)
The term derived from 2 latin words e=from; volvere= to roll and means the act of unrolling or unfolding
Charles Darwin (1859) has defined evolution as ‘descent with modification’ i.e., closely related species resembling one another because of their inheritance and differing from one another because of the heredity.
In other words evolution is the process by which related populations diverge from one another, giving rise to new species (or higher group).
S.Banerjee (Krishti Education)

3. S.Banerjee (Krishti Education)
Proved of Evolution
Comparisons of structure of living and fossil forms.
On the sequence of appearance and extinction of species in past ages.
On the physiological and biological similarities and differences between species.
S.Banerjee (Krishti Education)

4. S.Banerjee (Krishti Education)

5. How Evolution is Brought About
Differential Survival-adaptive characteristics
Mechanism of Inheritance
Sexual reproduction- produce new and novel combination
Isolating mechanism – barrier
Adaptation
Point mutation
Genetic drift – fluctuation of gene frequency
S.Banerjee (Krishti Education)

6. Theories put forward to explain evolution
S.Banerjee (Krishti Education)

7. Theory of Inheritance of acquired charecteristic (LAMARCKISM)
S.Banerjee (Krishti Education)

8. S.Banerjee (Krishti Education)
Major Facts
Internal forces of life tend to increase the size of the organism
Direct environmental effect over living organism
Use and disuse
Inheritance of acquired characteristics
Example:
Giraffe
S.Banerjee (Krishti Education)

9. S.Banerjee (Krishti Education)
Why rejected?????
New organ result from new need : Birds can fly so can’t I??
Inheritance of acquired characters – experiment of tail length of rat
S.Banerjee (Krishti Education)

10. S.Banerjee (Krishti Education)
Neo Lamarckism
S.Banerjee (Krishti Education)

11. Theory of Natural Selection (DARWINISM)
S.Banerjee (Krishti Education)

12. Factors that influenced Darwin’s Thoughts
Species gradually become modified with time, that not all species survived through ages
Living species have ancestor
Species change not only with time but also with geographical distance
S.Banerjee (Krishti Education)

13. S.Banerjee (Krishti Education)
Loxodonta africana Elephas maximus indicus
S.Banerjee (Krishti Education)

14. S.Banerjee (Krishti Education)

15. Charles Darwin (1809-1882) Sailed around the world 1831-1836
S.Banerjee (Krishti Education)

16. What did Darwin travel revel?
The observations led him To develop the theory Of Evolution!!!
S.Banerjee (Krishti Education)

17. S.Banerjee (Krishti Education)
Natural Selection
S.Banerjee (Krishti Education)

18. S.Banerjee (Krishti Education)

19. S.Banerjee (Krishti Education)

20. S.Banerjee (Krishti Education)
Natural Selection
S.Banerjee (Krishti Education)

21. S.Banerjee (Krishti Education)
Thank You
S.Banerjee (Krishti Education)

22. S.Banerjee (Krishti Education)