1. Other Evidence

2. Ontogeny, Phylogeny, and Recapitulation Ontogeny recapitulates phylogeny!

3. Ontogeny: is the history of the development of an organism through its entire life. Early developmental and ebryological features contribute greatly to our knowledge of homology and common descent. Ontogeny, Phylogeny, and Recapitulation

4. –Many vertebrates have common embryonic structures Post-anal tail Pharyngeal pouches Chick embryoHuman embryo

6. Ontogeny, Phylogeny, and Recapitulation Ernst Haeckel: Ontogeny (individual development) recapitulates (repeats) phylogeny (evolutionary descent).

7. Ontogeny, Phylogeny, and Recapitulation Haeckel based his law on the flawed premise that evolutionary change occurs by successively adding new features onto the end of an unaltered ancestral ontogeny while condensing the ancestral ontogeny into earlier developmental stages.

8. Ontogeny, Phylogeny, and Recapitulation K. E. von Baer, disagreed, he argued that early developmental features were simply more widely shared among different animal groups than later ones.

9. Fig. 1.19 p 19

10. Heterochrony We now know that there are many parallels between ontogeny and phylogeny, but this ancestral ontogeny can be shifted either to earlier or later stages in descendent ontogenies.

11. III. Multiplication of species Since evolution is a branching process, unless there is a high rate of extinction, more species will be produced through time.

12. III. Multiplication of species Since evolution is a branching process, unless there is a high rate of extinction, more species will be produced through time. But what then is a species?

13. Species Definition 1. Common ancestry

14. Species Definition 1.Common ancestry 2.Interbreeding

15. Species Definition 1.Common ancestry 2.Interbreeding 3.Genotypic and phenotypic cohesion

16. How does speciation occur?

17. 1.Reproductive barrier (allopatric speciation).

18. How does speciation occur? 1.Reproductive barrier (allopatric speciation). 1.Geographic isolation (Vicariant speciation) 1.Mountain range 2.Glaciers

19. Ensatina eschscholtzii

22. Fig. 1.21 p 22

23. How does speciation occur? 1.Reproductive barrier (allopatric speciation). 1.Geographic isolation (Vicariant speciation) 1.Mountain range 2.Glaciers 2.Colonization (founder effect)

24. Founder Event

25. How does speciation occur? 1.Reproductive barrier (allopatric speciation) 1.Geographic isolation 1.Mountain range 2.Glaciers 2.Colonization (founder effect) 2.Without reproductive barrier (sympatric speciation). Speciation forming without geographic isolation.

27. 3) Adaptive Radiation: The production of ecologically diverse species from a common ancestral stock. How does speciation occur?

28. Adaptive Radiation: Species radiate from a common ancestor stock. Figure 1.23 p 23

29. IV. Darwin Argued that Species Arise by Gradualism

30. Based on Leyell’s theory of uniformitarianism.

31. IV. Darwin Argued that Species Arise by Gradualism Based on Leyell’s theory of uniformitarianism. States that larger changes in organisms occur by the accumulation of many smaller changes (i.e. evolution is a slow, continuous process)

32. Fig. 1.25, p 24 Gradualist model of evolution

33. What evidence would support Gradualism?

34. Fossil record should have a long series of intermediate forms connecting the phenotypes of ancestral and descendant populations.

35. What evidence would support Gradualism? So do we see lots of intermediate forms in the fossil record?

36. Others Argued that species arise by Punctuated Equilibrium

37. Phenotypic evolution is concentrated in relatively brief events of branching speciation, followed by much longer intervals of evolutionary stasis.

38. Fig 1.26, p 24 Punctuated Equilibrium model

39. Gradualism Vs. Punctuated Equilibrium So which one is correct?

40. V. Natural Selection Differential reproduction and survival of individuals carrying alternative, inherited traits.

41. V. Natural Selection Natural selection is the major process or mechanism by which evolution occurs in Darwin’s theory of evolution.

42. So how did Darwin come up with this explanation?

43. Darwin’s Observations

44. Observation 1: Organisms can produce more offspring than just replacing the parents

45. Darwin’s Observations Observation 1: Organisms can produce more offspring than just replacing the parents Observation 2: Number of individuals in a population remains constant

46. Darwin’s Observations Observation 1: Organisms can produce more offspring than just replacing the parents Observation 2: Number of individuals in a population remains constant Observation 3: Individuals within a species vary (size, color, behavior, etc..)

47. Darwin’s Observations Observation 1: Organisms can produce more offspring than just replacing the parents Observation 2: Number of individuals in a population remains constant Observation 3: Individuals within a species vary (size, color, behavior, etc..) Observation 4: Variation in individuals is heritable.

48. Darwin’s Deductions

49. Deduction 1: Individuals must compete for resources, and only some will survive

50. Darwin’s Deductions Deduction 1: Individuals must compete for resources, and only some will survive Deduction 2: Individuals with variations more suited to the environment will be more likely to survive and reproduce: natural selection

51. Darwin’s Deductions Deduction 1: Individuals must compete for resources, and only some will survive Deduction 2: Individuals with variations more suited to the environment will be more likely to survive and reproduce: natural selection Deduction 3: Over many generations and long periods of time, these variations accumulate in the population, resulting in evolution, or change over time.

52. Potential for rapid reproduction Relatively constant resources and population over time Variability in structures and behaviors Some variability inherited Competition for Survival and reproduction NATURAL SELECTION On average, the fittest Organisms leave The most offspring EVOLUTION: The genetic makeup of the population changes over time, driven by natural selection Conclusions Observation

53. Evidence for evolution 1)Artificial Selection 2)Fossil Record 3)Comparative anatomy 4)Homologous/vestigial structures 5)Embryology

54. After Darwin Neo-Darwinism: August Weismann’s change to Darwin’s theory by removing inheritance of acquired characteristics.

55. After Darwin Neo-Darwinism: August Weismann’s change to Darwin’s theory by removing inheritance of acquired characteristics. The synthetic theory: combination of Darwin’s and Mendelian genetics –Microevolution –Macroevolution

56. The Big Picture The theory of evolution was derived through the scientific method. REMEMBER: this makes evolution testable! After more than 100 years of intensive testing, Darwin’s theory has only been slightly altered. Evolution explains the diversity of life on earth.