The document summarizes the evolution of biological classification systems from Linnaeus' initial two-name system to the current three domain system. It describes how early classification grouped organisms based on physical similarities, while modern evolutionary classification is based on evolutionary relationships and genetic similarities revealed by molecular analysis. The three domain system divides all living things into Bacteria, Archaea, and Eukarya.

1. Chapter 18 Classification

3. 18 – 1 Finding Order in Diversity

4. Evolution has lead to a staggering variety or organisms Biologists have identified and named about 1.5 million species so far They estimate anywhere between 2 and 100 million additional species have yet to be discovered

5. Taxonomy The science of classifying and naming organisms

6. Assigning Scientific Names By the 18th century, European scientists recognized that referring to organisms by common names was confusing Common names vary among regions within a country

7. Mountain Lion

8. Cougar

9. Puma

10. Panther

11. Early Efforts at Naming Organisms First attempts at standard scientific names often described physical characteristics As a result, these names could be 20 words long! Ex.) The English translation of the scientific name of a particular tree might be “Oak with deeply divided leaves that have no hairs on their undersides and no teeth around their edges.”

12. Binomial Nomenclature Carolus Linnaeus (18th Century) Swedish Botanist Developed a system for naming organisms

13. Binomial Nomenclature Two word naming system

14. Rules for Binomial Nomenclature Written in italics First word is capitalized Second word is lowercased Ex.) Genus species Genus species G. species

15. The name often tells you something about the species Ex.) Tyranosaurus Rex Tyrant Lizard King

17. Taxon (taxonomic category) A group or level of organization

19. Linnaeus’s system of classification uses seven taxonomic categories Kingdom Phylum Class Order Family Genus species Largest / Least Specific Smallest / Most Specific

20. Mnemonic Device Kingdom Phylum Class Order Family Genus species King Phillip Came Over For Good Soup

22. 18 -2 Modern Evolutionary Classification

23. Problems with Traditional Classification Sometimes, due to convergent Evolution organisms that are quite different from each other evolve similar body structures Ex.) Crab, limpet, barnacle

25. Evolutionary Classification Darwin’s theory of evolution changed the entire way that biologists thought about classification Biologists now group organisms into categories that represent lines of evolutionary descent , not just physical similarities

26. Classification Using Cladograms Many biologists now prefer a method called cladistic analysis This method of classification identifies and considers only those characteristics that arise as lineages evolve over time

27. Derived characteristics Characteristics that appear in recent parts of a lineage but not in its older members

28. Cladograms Diagram that shows the evolutionary relationships among a group of organisms

30. Similarities in DNA and RNA Suppose you were trying to compare diverse organisms such as yeast and humans It wouldn’t make sense to try to classify anatomical similarities The genes of many organisms show important similarities at the molecular level These similarities can be used as criteria to help determine classification Ex.) Myosin in humans & yeast

31. Molecular Clocks Use DNA comparison to estimate the length of time that two species have been evolving independently

32. Molecular Clocks Mutations happen all the time at about the same rate A comparison of DNA sequences in two species can reveal how dissimilar the genes are The degree of dissimilarity is an indication of how long ago the two species shared a common ancestor

34. 18 -3 Kingdoms and Domains

35. In taxonomy, as in all areas of science, ideas and models change as new information arises, some explanations have been discarded altogether, whereas others such as Darwin’s theory of evolution by natural selection, have been upheld So it should not be surprising that since the 1800’s, the tree of life has been revised and edited since the discovery of all this new information

36. The Tree of Life Evolves Before Linnaeus’s time, the only two Kingdoms that existed were Plants and Animals As scientists discovered new organisms that didn’t fit into the plant or animal category, they made a new category

37. The Old 5 Kingdom System Animals Plants Fungi Protist Bacteria

38. In recent years, as evidence about microorganisms continued to accumulate, biologists come to recognize that the Monera were composed of two distinct groups

39. The New 6 Kingdom System Animals Plants Fungi Protist Eubacteria Archaebacteria

41. The Three Domain System Molecular analysis has given rise to a new taxonomic category that is now recognized by many scientists

42. Domain Larger than a kingdom

43. 3 Domains Bacteria Eubacteria 2. Archaea Archaebacteria 3. Eukarya Protists, fungi, plants, animals (Everything with a nucleus)

44. Domain Bacteria Unicellular Prokaryotic - no nucleus, no membrane bound organelles Thick walls (containing peptigoglycan) Free living and parasitic Important decomposers Some photosynthesize Some don’t need oxygen Anerobic Some need oxygen Aerobic

48. Petri dish Agar Bacteria Colonies

49. What is this used for?

51. Domain Archaea Unicellular Small Prokaryotic Live in extreme environments Ex.) volcanic hotsprings, brine pools, black organic mud without oxygen

52. Acidophiles – live in acidic environments Thermophiles – can tolerate hot temperatures 50 – 110 degrees Halophiles – can stand extreme concentrations of NaCl Methanogens – Produce methane CO 2 + H  CH 4

53. Acidophiles

54. Thermophile

55. Halophile

56. Domain Eukarya Consists of all organisms that have a nucleus

57. Protista Small Mostly unicellular Eukaryotic – has a nucleus, and membrane bound organelles Cannot be classified as animals, plants or fungi, but share many characteristics with plants, animals and fungi

58. Plant like Protists Algae Photosynthetic – can make their own food

59. Euglenas Flagella

60. Diatoms

61. Dinoflagellates

62. Dinoflagellates Red tide

63. Green Algae

64. Red Algae

65. Brown Algae

66. Animal like Protists Protozoans Heterotrophic – can’t make their own food

70. Fungus like Protists Slime molds, water molds Decompose their food

72. Fungi Mostly multicellular Ex.) Mushroom, yeast Cell walls

73. Fungi Heterotrophs Feed on decaying organic matter Secrete digestive enzymes into food source then Spread and reproduce by spores

74. Spores Reproductive cells that form new organisms without fertilization

75. Many are used in medicine Antibiotics Anti rejection Anti viral

76. Penicillium

77. Plantae Multicellular Photosynthetic autotrophs – make their own food by photosynthesis Non-motile Cell walls (cellulose)

78. Animalia Multicellular Heterotrophic No cell walls Most move Incredible diversity