Evolution, mechanism of evolution

1. MECHANISM OF EVOLUTION

2. Contents:
1.Introduction to EVOLUTION
-What is EVOLUTION?
- How EVOLUTION occur?
- Theories of Evolution.
2.Forces of Evolution.
3.Mechanism of Evolution.

3. What is EVOLUTION ?

4. EVOLUTION:
• EVOLUTION is defined as a change in the genetic
composition of a population over successive
generations.
• When we hear “evolution”, we often think of
progressive change.

5. How Evolution occur?
• Evolution can occur if there is genetic variation within
a population.
• Genetic variation is essential for evolution.
• For a variation to contribute to evolution change,it
must be heritable.
• There are two sources of variation
1.Mutation
2.Recombination

6. THEORIES OF EVOLUTION:
LAMARCKISM :
• Proposed by Lamarck.
• In the year 1809.
• Use and Disuse.

7. DARWINISM
• Proposed by Charles Darwin .
• In the year 1859.
• Survival of Fittest.
• Natural Selection.

8. Forces of Evolution :
1.Mutation
2.Gene flow
3.Non-random mating
4. Genetic drift
5.Natural Selection

9. Mechanisn of Evolution

10. 1. Mutation:
• A random change in the genetic composition of an organism
due to chance in the DNA sequence.

11. 2. Gene flow :
• The movement of alleles into, or out of a gene pool( population).
• If results in immigration or emigration.

12. 3. Non-random mating :
• Non-random mating can occur when individuals prefer
mates with particular superior physical character or by the
preference of individuals to mate.

13. 4. Genetic drift:
• The change in the composition of gene pool as a result of a
chance or random event.
• Founder effect

14. 5.Natural selection:
• The process by which organisms thataremost suited to their
environment survive and reproduce most
successfully(survival of fittest).