Lamarck's and Darwin

1. THEORIES OF EVOLUTION
Prepared by:T.khai

3. Jean Baptists de Lamarck
■In 1809 observed
that fossils of
invertebrates bore
certain similarities
with modern
invertebrates.

4. Theory of Acquired Traits
THIS CAN BE SUMMARIZED INTO:
■1. organisms desire to improve
themselves and become more
advanced

5. 2.The effort to improve causes
same body structures to be
constantly used, others are not
used.The frequently used body
structures develop, while unused
structures weaken and eventually
disappear.This is known as the
Principle of Use and Disuse.

6. 3. Modifications of structures due to use or
disuse are inherited by the offspring's. This
is called the Principle of Inheritance of
Acquired Characteristics.
The example is the giraffe’s neck becomes
longer to get food.

8. Theory of Natural Selection

10. Charles Robert Darwin
■(1809-1822) is
credited with
developing the
theory of natural
selection, or
“Survival of the
Fittest”

11. 1.The number of offsprings
is usually greater than the
available resources
necessary for survival.

12. 2. Every organism
must struggle to
survive.

13. 3. Some variations
allow members to
survive and reproduce
better than others.

14. 4. Organisms that survive and
reproduce pass their traits to their
offsprings and helpful traits gradually
appear in more and more.These
variations enable them to “fit” into
their environment and those who lack
these are eliminated.