Essential Question: What are some theories about the origin of life on earth?

1. Essential Question: What are some theories about the origin of life on earth?

2. EVOLUTION The process by which modern organisms descend from ancient organisms

3. Conditions on Early Earth • 4.5 billion years ago • Violent storms & 100 years of rain • Primitive atmosphere • 1000s of active volcanoes giving off toxic gasses: H2, N2, H2O, CO2 • Extremely hot temperatures • 1000 mile-an-hour winds (no O2 until 2.3 by later)

4. Later, Alexander Oparin hypothesized that the gases in the primitive atmosphere lead to the formations of organic molecules and finally living things.

5. Then, Miller and Urey tested Oparin’sexperiment & found that life could have arisen from simpler compounds present on a primitive Earth, giving rise to Microspheres

6. Formation of Microspheres Large organic molecules form tiny bubbles called proteinoid microspheres. • Microspheres are not cells, but they have selectively permeable membranes and can store and release energy – suggesting that microspheres may have given rise to cells

7. Introduction of Oxygen • The first life-forms evolved without oxygen • About 2.2 billion years ago, photosynthetic bacteria began to pump oxygen into the oceans. • Next, oxygen gas accumulated in the atmosphere. The rise of oxygen in the atmosphere drove some life forms to extinction, while other life forms evolved new, more efficient metabolic pathways that used oxygen for respiration. O2

8. The Endosymbiotic Theory States that: • Eukaryotic cells formed from a symbiotic relationship with several different prokaryotes BECAUSE • About 2 billion years ago, prokaryotic cells began evolving internal cell membranes. • The result was the ancestor of all eukaryotic cells.

9. Origin of Eukaryotic Cells • Endosymbiotic Theory Ancient Prokaryotes Chloroplast Plants and plantlike protists Aerobic bacteria Photosynthetic bacteria Nuclear envelope evolving Mitochondrion Primitive Photosynthetic Eukaryote Animals, fungi, and non-plantlike protists Primitive Aerobic Eukaryote Ancient Anaerobic Prokaryote

10. Origin of Eukaryotic Cells Aerobic bacteria Ancient Prokaryotes Nuclear envelope evolving Ancient Anaerobic Prokaryote

11. Origin of Eukaryotic Cells Mitochondrion • Prokaryotes that use oxygen to generate energy-rich molecules of ATP evolved into mitochondria. Primitive Aerobic Eukaryote

12. Origin of Eukaryotic Cells Prokaryotes that carried out photosynthesis evolved into chloroplasts. Chloroplast Photosynthetic bacteria Primitive Photosynthetic Eukaryote

13. Essential Question: What evidence is there that evolution has occurred?

14. Evidence of Evolution The remains of a once living thing 1. Fossils Types imprints molds petrified or frozen organisms

15. (2) Radioactive dating • Half-life - Time it takes for one half of a given quantity of a radioisotope to decay

16. 3. Comparative Anatomy a. Homologous structures - parts of the body that are similar in structure show evidence of common origin

17. b. Analogous structures – parts of the body that are similar in function but not structure – does not show common origin. Bird’s wing and bee’s wing are analogous structures

18. c. Vestigial structure – structures that no longer function in the body – may show relationship with other organisms, indicate common origin. Examples: appendix or a whale’s pelvis

19. 4.Comparative Embryology • Early vertebrate embryos strongly resemble one another • Same plan of development

20. Two theories of Evolution Jean Baptist Lamarck – Theory of Acquired Characteristics Traits you develop you pass on---ACQUIRED TRAITS

21. How would Lamarck explain the long neck on the giraffe?

23. Would her children have longer necks?

24. Charles Darwin Theory of Natural Selection Survival of the Fittest Fig. 17.5a, p. 274

25. Darwin Wolf Pinta Genovesa Marchena Santiago Bartolomé Seymour Råbida Baltra Pin zon Fernandia Santa Cruz Santa Fe Tortuga San Cristobal Española Floreana Galapagos Islands SSS Beagle EQUATOR Galåpagos Islands Isabela Fig. 17.5b, p. 275

26. Darwin’s Finches • Each islands in the Galapagos had their own species of finch • Each bird had a unique beak adapted for the food source of that island • Because the birds were all similar: Darwin realized they must have evolved from a common ancestor

27. Fig. 17.7, p. 277

28. KONA FINCH extinct KAUAI AKIALAOA AMAKIHI LAYSAN FINCH IIWI AKIAPOLAAU APAPANE MAUI PARROTBILL fruit and seed eaters insect and nectar eaters Fig. 19.12 p. 303 FOUNDER SPECIES

29. 1 A few individuals of a species on the mainland reach isolated island 1. Speciation follows genetic divergence in a new habitat. 3 2 4 Later in time, a few individuals of the new species colonize nearby island 2. In this new habitat, speciation follows genetic divergence. 1 2 Speciation may also follow colonization of islands 3 and 4. And it may follow invasion of island a by genetically different descendants of the ancestral species. 1 3 2 4 Fig. 19.11 p. 303

30. Theory of Natural Selection 1. Overpopulation: as populations increase their resources decrease

31. Theory of Natural Selection 1. Overproduction – leads to 2. Struggle for Existence –competition occurs food, shelter and living space.

32. Theory of Natural Selection 1. Overproduction 2. Struggle for Existence 3. Genetic Differences: give some organisms an advantage

33. Theory of Natural Selection 1. Overproduction 2. Struggle for Existence 3. Variations 4. Natural Selection: those members best adapted will survive longer & reproduce offspring with the advantageous traits.

34. Theory of Natural Selection 1. Overproduction 2. Struggle for Existence 3. Variations 4. Natural selection 5. Speciation: over time variations in an isolated population will eventually produce a new species

35. How Natural Selection Works Example: The Peppered Moth The peppered Moth, Biston beularis, lives in England. There are two colors of this moth.

36. Before the Industrial Revolution the bark of trees were light colored because they were covered with grey-green lichens. If you were a bird which moth would you eat?

37. After the Industrial Revolution the bark of the trees were dark because the lichens were killed by pollution. Which moth is visible now?

38. Other Examples of Natural Selection • Bacteria becoming resistant to antibiotics • Insects becoming resistant to pesticides

39. Patterns of Evolution Different patterns provide different paths to explain the degree of variation among organisms • Convergent Divergent

40. Convergent Evolution: two different species that did not come from a common ancestor but are very similar in appearance and life style, Example: sharks and dolphins Divergent Evolution: two different species that came from a common ancestor, Example: horse and donkey

41. Natural selection can affect the distributions of phenotypes in any of three ways: 1.Directional Selection  • individuals at one end of the curve have higher fitness than individuals in the middle or at the other end

42. 2. Stabilizing Selection  When individuals near the center of the curve have higher fitness than individuals at either end of the curve

43. 3. Disruptive Selection  • When individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle

44. Genetic variation is studied in populations. A population is a group of individuals of the same species that interbreed. A gene poolconsists of all genes, including all the different alleles, that are present in a population. Genes & Variation

45. Relative Frequency: is the number of times the allele occurs in a gene pool used to • Predicts how often a particular allele will be expressed. In genetic terms, Evolution is any change in the relative frequency of alleles in a population

46. Sources of Genetic Variation Mutations - any change in a sequence of DNA can produce an organism with better adaptive skills

47. Genetic Drift: A random change in allele frequency • Genetic drift may occur when a small group of individuals colonizes a new habitat. • Individuals may carry alleles in different relative frequencies than did the larger population from which they came. • The new population will be genetically different from the parent population • When allele frequencies change due to migration of a small subgroup of a population it is known as the Founder Effect.

48. Evolution Versus Genetic Equilibrium • The Hardy-Weinberg Principlestates that allele frequencies in a population will remain constant unless one or more factors cause those frequencies to change. • When allele frequencies remain constant it is called: Genetic Equilibrium

49. Evolution Versus Genetic Equilibrium To maintain genetic equilibrium from generation to generation: 1. Random mating must occur 2. Need very large population 3. No immigration or emigration 4. No mutations 5. No natural selection

50. Speciation • The formation of a new species A species is a group of organisms that breed with one another and produce fertile offspring.