2. Evolution – A Theory In science, a theory is a testable, well supported scientific explanation of events in the natural world. A theory is a scientific statement which is still not absolutely proven to be true. A scientific theory may ultimately be proven to be true or false.

3. The Origin of Life Life on Earth began about 3.5 billion years ago. The Earth was covered in a hot, thin soup of water and organic materials. Over time, the molecules became more complex and could run metabolic processes. This is how molecules such as nucleotides, proteins and ATP were formed.

4. The Origin of Life: The Heterotroph Hypothesis The Earth’s atmosphere was different.

5. FOSSILS

6. Fossils Form In Sedimentary Rock -over time, pieces of earth erode and are worn away by wind and water. Layers of eroded earth are deposited on top of each layer. These layers press down until the bottom layers turn into rock.

7. Preservation in Volacanic Ash- Eruption of Vesuvius in 80 BC

8. Two of the creatures that left their footprints across this landscape of volcanic ash, 3.6 million years ago, were members of the early human species Australopithecus afarensis,, walking along side each other.

9. Refrigeration of Soft Parts This frozen baby wooly mammoth probably lived 22,000 years ago. It was found in Siberia in 1997.

10. Ice Man (Austria)

11. Insects in Amber

12. Transitional Series

13. Humans walked more upright, developed a distinct neck and reduced brow ridge. Transitional Series

14. Archaeopteryx Intermediate Forms

15. Monotremes Intermediate Forms -anteaters, duck- billed platypus -egg laying mammals -skulls almost birdlike -no teeth as adults

16. Intermediate Forms

17. Vestigial Structures appendix vestigial leg bones

18. Vestigal structures The vestigial wings of this flightless cormorant are too small to allow it to fly.

20. Comparison of Proteins: Hemoglobin Comparison SpeciesAmino Acid Differences Gorilla1 Rhesus monkey8 Mouse27 Chicken45 Frog67 Lamprey125

21. Evidence from Embryology

23. Lamarck: Theory of Use and Disuse appendix The selective use or disuse of organs leads to acquiring or losing certain traits during an organism’s lifetime. These traits can then be passed onto offspring. Over time, there is a change in the species. This theory is not true!

25. Lamarck’s Theory of Acquired Characteristics

26. tail X tail cut off tail Weismann Theory of Acquired Characteristics Disproved

27. Darwin Voyage of the Beagle 1859- On the Origin of Species by Means of Natural Selection is written.

28. Galapagos Tortoises Marine Iguana Flightless Cormorant Darwin found different characteristics on different islands- each well suited to their environment.

30. Theory of Natural Selection Species are not perfect or unchanging. There is natural variation among offspring. This variation among offspring is inherited. There is overpopulation- this leads to competition for resources-a struggle for existence. This leads to survival of the fittest.

31. “Evolution by Natural Selection” Fitness is a result of an organism’s adaptations: inherited traits that increase an organism’s chance of survival. Those organisms that are the most fit survive ► reproduce ► pass on their traits to their offspring. Examples: porcupine’s sharp quills, faster birds, animals that hunt in packs

32. “Evolution by Natural Selection” Variations occur – descent with modification. Over time, natural selection produces organisms with different structures to suit their environment. Changes in Gene Frequency Changes in Species

33. Sources of Variations mutations crossing over during meiosis recombination of genes at fertilization

34. Changes in Gene Frequency as a Result of: geographic isolation reproductive isolation environmental changes

35. Geographic Isolation at the Grand Canyon

36. Behavioral Isolation Differences in Mating Calls

37. The Founder Principle A small number of people have many descendants surviving after a number of generations. High frequencies of specific genetic traits are inherited from a few common ancestors. Example: Amish people in Lancaster, Pennsylvania are descended from a few dozen people in Germany. There is a high incidence of a rare fatal genetic disorder (microcephaly).

38. Bottleneck Effect A catastrophe occurs during which most individuals of a species die, without passing on their genes. This causes a reduction in the genetic diversity of the species.

39. Changes in Species Resulting From: resistance (insects, bacteria) industrial melanism (peppered moths)

40. Industrial Melanism- Kettlewell’s moths European peppered moths have 2 color variations. The darker moths (with more melanin) were rare until industrial pollution in the 1850s, when tree trunks darkened due to soot.

41. Convergent Evolution The development of similar appearance, structures, or behavior in unrelated species/ populations because organisms live in similar habitats. Example: the wings of a bird and the wings of an insect; the body plan of a shark and a dolphin.

42. Convergent Evolution

44. Divergent Evolution A single group of organisms splits into groups that evolve in different directions.

45. Species – a group of organisms that can breed together under natural conditions to produce fertile offspring. X

46. horse infertile mule - donkey X - not a species

47. Father = tiger Mother = lion Father =lion Mother =tiger TiglonLiger sterile and do not mate under natural conditions- not a species