Evolution

1. Evolution

2. 3/27/12 • Objective: Introduce origins theories • Do Now: Hand in popular science questions • Do Later: Read sections 13.1-3

3. Diversity of life • Estimated 10 million species on earth • Phylogenetic trees show relationships

4. Origins Theories • Lamarck • Spontaneous generation • Simple organisms are more recent • Complex organisms are older, gained complexity over time • Theory of Acquired Characteristics • Characteristics acquired by parents get passed on to offspring

5. Origins Theories

6. Origins Theories • Catastrophism • Rapid, catastrophic events shape geology and extinction • Gradualism • Slow change of geologic features and life forms over time Georges Cuvier Charles Lyell

7. Origins Theories • “Descent with modification” • Species have natural variation • Certain characteristics are favored over time

8. Natural Selection • Condition 1: Variation • Populations must have variation in traits for selection to occur

9. Natural Selection • Condition 2: Competition • “Survival of the fittest” • Scarce resources, avoiding predators, etc. • Only the best adapted species survive

10. Natural Selection • Condition 3: Inheritance • Favorable traits are passed on to offspring • Genetic inheritance

11. Natural Selection • Theory of Natural Selection • Heritable traits that confer an advantage in survival and reproduction will increase in frequency in a population. • Gradually a population will change as a result of natural selection.

12. Artificial Selection • Selection performed by a conscious agent. • Dog breeding • Crop selection

13. 4/2/12 • Objective: To examine speciation and evidence for natural selection • Do now: • Discuss with a partner – What is a species? • Come up with a definition in pairs • Do later: Read 13.5-6 in text • On separate paper: Pg. 275 #1, 3-7, 12

14. Species • A species is a group of organisms that are able to interbreed and produce fertile offspring. Mules are the offspring of a male donkey and a female horse. They are sterile.

15. Hybrid Species Zebra + horse  zebroid (sterile) Tiglons can occasionally reproduce with difficulty.

16. Speciation • How do new species come to be (speciation)? • 1) Population is separated • 2) Each population changes due to natural selection • 3) Differences accumulate to make interbreeding impossible

17. Evidence for Natural Selection • Biogeography • Geographic distribution of species Why do all marsupials live in Australia?

18. Evidence for Natural Selection • Homologous Structures • Anatomically similar structures in groups of related organisms • May serve different functions

19. Evidence for Natural Selection • Molecular Biology • DNA sequencing can confirm the relationship between two species • Few genetic differences = closely related • Many genetic differences = distantly related 98.5% similar

20. 4/3/12 • Objective: • Do Now: • Pick two evidences for evolution and explain (in writing) how they show “descent with modification”. (3 minutes) • Do Later:

21. Evidence for Natural Selection • Vestigial Structures • Structure that is no longer used in an organism • Artifact of a useful structure in an ancestor

22. Vestigial Structures • Whale pelvis

23. Vestigial Structures • Human Coccyx

24. Vestigial Genes • Vestigial genes – organisms have genes in their DNA that are no longer active • Chicken teeth • Genes for teeth can be turned back on in chickens

25. Transitional forms • Fossil evidence of an intermediate form between a present day species and an ancestor.

26. Transitional Forms • Archaeopteryx – transitional form between dinosaurs and modern birds Archaeopteryx – between dinosaurs and aves (birds)

27. Transitional forms • Tiktaalik • Transitional form between aquatic and land animals • “lobe finned fish”

28. Transitional Forms Basilosaurus – intermediate between land mammals and whales whale

29. Comparative Embryology • Early stages of development are similar across the animal kingdom

30. 4/6 • Objective: To discuss pesticide and antibiotic resistance • Do later: Popular Science – Pesticide and antibiotic resistance

31. Pesticide Resistance • Application of pesticides selects for pesticide resistance Red = pesticide resistant White = wild type (‘normal’)

32. Pesticide Resistance • Colorado Potato Beetle • Agricultural pest • Resistant to all major classes of insecticides

33. Pesticide Resistance • Can you think of any ways to combat pesticide resistance? • Pesticide rotation • Natural predators • Diversifying crops The fungus Beauveriabassianais toxic to many beetles but non-toxic to humans Diversifying crops can limit the spread of pests

34. Antibiotic Resistance • Use of antibiotics selects for antibiotic resistant bacteria. • Drug resistance evolves over time.

35. Antibiotic Resistance • Methicillin-Resistant Staph Aureus (MRSA) • “Staph infection” • Resistant to many classes of anti-staphylococcus drugs

36. Antibiotic Resistance • Extensively Drug Resistant Tuberculosis (XDR-TB) • Lung disease • Resistant to three or more major anti-TB drug classes • High mortality (50% +)

37. Antibiotic Resistance • Solutions? • Limit prescription of antibiotics • Limit use of antibiotics in agriculture • Use full prescriptions • Vary prescriptions

38. 4/17/12 • Objective: To examine varieties of selection • Do Now: • With a partner, describe the differences between natural selection, artificial selection, and sexual selection. Provide an example of each. • Do later: • Read 13.13 and 13.17 in text

39. Stabilizing Selection • Selection that favors intermediate phenotypes Stabilizing selection regulates birth weight

40. Directional Selection • Selection that favors extreme phenotypes in one direction Peppered moths

41. Disruptive Selection • Selection that favors extreme phenotypes in both directions Galapagos iguanas

42. Practice time! • With a partner, come up with an example of stabilizing and directional selection. • Challenge: Can you think of an example of disruptive selection?

43. Popular Misconceptions • Natural Selection does not createany traits. • It only selects on existing traits. Where do new traits come from?

44. Popular Misconceptions • Natural Selection is not goal oriented • Simpler organisms are older, but not less fit.

45. Popular Misconceptions • Natural Selection is subject to constraints • Advantageous traits often come with trade-offs

46. 4/20/12 • Objective: To learn about hypotheses for the origin of cells • Do Now: In your notes, make a T chart to compare the conditions of early and modern Earth • Do Later: Read Ch. 15.1-3 in text

47. Early Earth Modern Earth

48. Evidence for Early Life • Stromatolites – 3.5 billion years old • Oldest fossils • Single celled organisms • Grow in mats that harden into rock

49. Cell Theory • Cell theory • All living things are composed of cells and their products • New cells arise from the division of older cells • Cells are the basic building blocks of life • Where did the first cells come from?

50. Miller’s Experiment • Stanley Miller (1953) • Hydrogen gas (H2) • Ammonia (NH3) • Methane (CH4) • Water vapor • Spark • Product? Amino acids.