EVOLUTION

Life on earth began as simple and primitive

forms, by natural selection, over a long time various complex

organisms form

Evidences of Evolution

1. Paleontology

2. Geographical distribution of

organisms

3. Comparative anatomy

4. Embryology

5. Comparative bio-chemistry

PaleontologyStudy of fossil:

Differences between ancient and recent form of an organism

Development of Horse

Development of Whale

Geographical distribution of organisms

Owing to geographical isolation, organisms adapted to that isolated

habitat and become different. (adaptive radiation)

Migration between continents

Finch Beak

Galapagos tortoise

Comparative anatomyHomologous structures as pentadactyl limb have same fundamental structure but different function

Eye Evolution

Although adult structure is different, structure in embryonic stage is similar.

Embryology

Comparative bio-chemistry

Mechanism of Evolution

Lamarck’s Theory• Change in environment• Organism modify itself• More used organ enlarge• Less used degenerate• The acquired character is

inheritable

Darwin’s Theory• Change in environment• Population has inborn

different• Some good feature fit the

environment survive (natural selection)

• These reproduce and become new species

Neo-Darwinism1. Variation : Mutation and sexual reproduction

2. Natural Selection: The fittest has better chance to survive

and reproduce

3. Speciation: New species formation is caused by isolation

•Geographic isolation: physical barrier

•Ecologic isolation: different season or zone in habitat

•Reproductive isolation: different reproductive behavior

•Genetic isolation: genetic different due to isolation

Example