The Theory of Evolution

1. The Theory of Evolution

2. The theory of Evolution • Evolution is known as the gradual change in the characteristics of a species over time.

3. The theory of Evolution • A species is a group of organisms whose members look alike and successfully reproduce among themselves.

4. The Theory of Evolution • Charles Darwin is considered to be the founder of modern evolutionary theory.

5. The Theory of Evolution • On the Origin of Species established evolution by common descent as the dominant scientific explanation of diversification in nature.

6. Natural selection is a mechanism for changes in populations that occurs when organisms with favorable variations survive, reproduce, and pass on traits to the next generation.

8. Evidence for Evolution • All living things contain similar DNA, RNA, and proteins. • By comparing DNA sequences of two organisms, scientists can determine whether or not the organisms are closely related. • The relationship can then be used to construct evolutionary pathways.

10. Evidence for Evolution • Fossils also provide evidence for evolution. Fossils are the remains of once-living things that are preserved in Earth’s rocks.

11. Evidence for Evolution • Fossils have found that many simpler life forms exist early in Earth’s history. • The oldest fossils found are bacteria that lived 3.8 billion years ago.

12. Evidence for Evolution • A paleontologist is someone who studies fossil evidence

13. Which layer is Oldest?

15. Evidence for Evolution • Other kinds of evidence that support organic evolution are adaptations. These adaptations can be either: • Anatomical • Physiological

16. What do you notice about these structures?

17. Anatomical • Homologous structures have different function but the SAME structures. These similarities indicates that the organisms probably had a common (the SAME) evolutionary origin.

18. AND … what do you notice about these structures?

19. Anatomical • Analogous structures have body parts that are similar in function but different in structure. These indicate that the organisms had different yet related ancestors.

20. Anatomical • Some adaptations involve changes in the structure of body parts: mimicry and camouflage. • Mimicry enables an organism to copy the appearance of another species.

21. MIMICRY

22. Milk Snake Coral Snake

23. Anatomical • Some adaptations involve changes in the structure of body parts: mimicry and camouflage. • Camouflage is a structural adaptation that enables an organism to blend in with its surroundings.

24. CAMOUFLAGE

25. Functionless Structures ?? • Some body structures, such as the human appendix and the eyes of cave fish, have reduced forms. • These structures support the theory of evolution because they show structural changes over time.

26. Physiological Adaptations • Some adaptations are physiological or changes in an organism’s metabolic processes. • Keep in mind that all things are made up of cells and the organelles are structurally and functionally similar in most organisms.

27. Physiological Adaptations • Organisms are constantly changing to adapt to their environment. Organisms that have been exposed to antibiotics and pesticides have become “selected” to survive because they are physiologically more resistant.

28. Imagine that there are 10bacteria growing on your hand.

29. You use Germ-x to clean your hand everyday.

30. After 4 days, there are still 3 bacteria on your hands that have survived.

31. Is there anything special about these bacteria? Yes..they have something about their DNA that has made them different and strong enough to survive. So now what will happen?

32. Those 3 that are “resistant” will undergo Mitosis.

33. And after a week, your hands will be covered with tons of bacteria that are ALL resistant to Germ-X. 

34. Take a Look!! What do you notice about these organisms?

35. Embryology • The study of the development of embryos is the field of embryology. • Studies of certain embryos indicate evolution from a common ancestor.