Order from Chaos: The Art of Classifying Organisms

1. Section 18-1 Order From Chaos • When you need a new pair of shoes, what do you do? You probably walk confidently into a shoe store, past the tens or hundreds of pairs of shoes you don’t want and straight to the kind you do want. How do you find them? Shoes are organized in the store in categories. People organize objects by grouping similar objects together.

2. Section 18-1 • 1. Consider the task facing early biologists who attempted to organize living things. How might they have begun? • 2. Suppose that you have been given a green plant, stringy brown seaweed, a rabbit, a mushroom, a worm, and a grasshopper. You’ve been asked to organize these things into categories that make sense. How would you do it? • 3. Decide on your categories and write each on a sheet of paper. Next to each category, write the defining characteristics of that category. Then, write in the organisms that fall into each category.

4. Section 18-1 • 18–1 Finding Order in Diversity A. Why Classify? B. Assigning Scientific Names 1. Early Efforts at Naming Organisms 2. Binomial Nomenclature C. Linnaeus’s System of Classification

5. Section 18-1 • Why classify? • To study the diversity of life we use a classification system to name organisms and group them in a logical manner • taxonomy- the discipline of classifying, organizing and naming organisms

6. Section 18-1 • Assigning Scientific Names • Confusion of common names for same animal and for different species. • ex. mountain lion, buzzard • Early attempts to classify organisms into a standard scientific name resulted in long descriptive names and still allowed for inconsistencies in their attempt of description

7. Section 18-1 • Binomial Nomenclature • Carl Linnaeus during the eighteenth century developed a two-word naming system called binomial nomenclature • ►each species was assigned a two part • scientific name • ►the first name would be capitalized and • both names italicized • Latin was used because it was a dead language that most scholars knew

8. Section 18-1 Linnaeus’s System of Classification Kingdom Contains seven levels of hierarchy. Kingdom being the most broad and species being the most specific. Phylum Class Order Family Genus Species

9. Section 18-1 • example: grizzly bear – Ursus arctos • Ursus- genus • contains 5 kinds of bears • arctos- species unique only to grizzly bear • maritimus- species unique only to polar bear

10. Figure 18-5 Classification of Ursus arctos Section 18-1 Coral snake Abert squirrel Sea star Grizzly bear Black bear Giant panda Red fox KINGDOM Animalia PHYLUM Chordata CLASS Mammalia ORDER Carnivora FAMILY Ursidae GENUS Ursus SPECIES Ursus arctos

11. Section 18-2 One Big Family? • How can you determine if one organism is closely related to another? It may seem easy, but it isn’t, and looks are often deceiving. For example, roses and orchids are both flowering plants, but roses grow on bushes or vines and have thorns. Many orchids don’t even grow in soil—they can grow in trees! Rose and orchid blossoms look very different, and roses and orchids cannot produce hybrids, or offspring of crosses between parents with different traits.

12. Section 18-2 • 1. Do you think roses and orchids are closely related? Explain your answer. • 2. Now, apply the same logic to dogs. Different breeds of dogs—such as a Labrador retriever and a collie—can breed and produce offspring. So what is the difference between the rose-orchid combination and the Lab-collie combination? • 3. What defines a species? Is appearance important? What other factors might be considered?

13. Species is the only “real” taxon. • - organisms determine who belongs to their species by who they mate with • - definition: group of organisms that can and do breed together in nature to produce fertile offspring. • - all other taxa are “invented” by man for man’s convenience

15. Section Outline Section 18-2 • 18–2 Modern Evolutionary Classification A. Which Similarities Are Most Important? B. Evolutionary Classification C. Classification Using Cladograms D. Similarities in DNA and RNA E. Molecular Clocks

16. Section 18-2 • The characteristics in which scientists group organisms together have changed over time. • Linneaus used visible similarities and differences • Present-day biologists group organisms into categories that represent lines of evolutionary descent. This is called evolutionary classification. • phylogeny- the study of evolutionary relationships among organisms

17. Section 18-2 • Superficial physical characteristics are sometimes deceiving when grouping organisms. • Convergent evolution has caused different species to have similar characteristics. • example: sugar gliders / flying squirrels; • butterfly vs. bat wings

18. Section 18-2 • Cladistic analysis is when scientists consider only new characteristics of organisms that arise as lineage evolve over time when grouping those organisms. • derived character – appear in recent part of lineage but not in its older members • cladogram – constructed by the use of derived characters and illustrates the relationships among a group of organisms

19. Traditional Classification Versus Cladogram Section 18-2 Appendages Conical Shells Crustaceans Gastropod Crab Crab Limpet Limpet Barnacle Barnacle Molted exoskeleton Segmentation Tiny free-swimming larva CLASSIFICATION BASED ON VISIBLE SIMILARITIES CLADOGRAM

20. Traditional Classification Versus Cladogram Section 18-2 Appendages Conical Shells Crustaceans Gastropod Crab Crab Limpet Limpet Barnacle Barnacle Molted exoskeleton Segmentation Tiny free-swimming larva CLASSIFICATION BASED ON VISIBLE SIMILARITIES CLADOGRAM

21. Section 18-2 • DNA and RNA can be used to help determine classification and evolutionary relationships. • Advantages: • 1. similar throughout all forms of life • 2. does not rely on superficial • physical characteristics • Molecular clock uses DNA comparisons to estimate the length of time two species have been evolving independently. Neutral mutations are the indicators of time of molecular clocks

22. Section 18-3 My Way or the Highway • Categories that are used to organize an assortment of things should be valid. That is, they should be based on real information. However, categories should be useful, too. Suppose that you are taking a survey of traffic. You sit at the side of a busy intersection and record the vehicles you see in one hour.

23. Section 18-3 • 1. What categories could you use to organize your count of vehicles? • 2. Look at your list of categories. Are all of them equally useful? • 3. Is there more than one valid and useful way to organize living things?

24. Section Outline Section 18-3 • 18–3 Kingdoms and Domains A. The Tree of Life Evolves B. The Three-Domain System C. Domain Bacteria D. Domain Archaea E. Domain Eukarya 1. Protista 2. Fungi 3. Plantae 4. Animalia

25. Section 18-3 • The view of life has changed drastically since Linnaeus first developed his 2 kingdom system. • ►1700s – Plant/Animal • ►1800s – Protista/Plant/Animal • ►1950s – Monera/Protista/Fungi/Plant • Animal • ►1990’s – Eubacteria/Archaebacteria/Protist • Fungi/Plant/Animal

26. Eukaryotic cells Prokaryotic cells Kingdom Plantae Kingdom Protista Domain Bacteria Domain Archaea Kingdom Fungi Kingdom Animalia Kingdom Eubacteria Kingdom Archaebacteria Concept Map Section 18-3 Living Things are characterized by Important characteristics which place them in and differing Domain Eukarya Cell wall structures such as which is subdivided into which place them in which coincides with which coincides with

27. Figure 18-12 Key Characteristics of Kingdoms and Domains Section 18-3 Classification of Living Things DOMAIN KINGDOM CELL TYPE CELL STRUCTURES NUMBER OF CELLS MODE OF NUTRITION EXAMPLES Bacteria Eubacteria Prokaryote Cell walls with peptidoglycan Unicellular Autotroph or heterotroph Streptococcus, Escherichia coli Archaea Archaebacteria Prokaryote Cell walls without peptidoglycan Unicellular Autotroph or heterotroph Methanogens, halophiles Protista Eukaryote Cell walls of cellulose in some; some have chloroplasts Most unicellular; some colonial; some multicellular Autotroph or heterotroph Amoeba, Paramecium, slime molds, giant kelp Fungi Eukaryote Cell walls of chitin Most multicellular; some unicellular Heterotroph Mushrooms, yeasts Eukarya Plantae Eukaryote Cell walls of cellulose; chloroplasts Multicellular Autotroph Mosses, ferns, flowering plants Animalia Eukaryote No cell walls or chloroplasts Multicellular Heterotroph Sponges, worms, insects, fishes, mammals

28. Figure 18-13 Cladogram of Six Kingdoms and Three Domains Section 18-3 DOMAIN ARCHAEA DOMAIN EUKARYA Kingdoms Eubacteria Archaebacteria Protista Plantae Fungi Animalia DOMAIN BACTERIA

29. Interest Grabber Answers Section 1 Answers • 1. Consider the task facing early biologists who attempted to organize living things. How might they have begun? • Students may say that early biologists attempted to formulate logical systems for organizing the diversity of life. • 2. Suppose that you have been given a green plant, stringy brown seaweed, a rabbit, a mushroom, a worm, and a grasshopper. You’ve been asked to organize these things into categories that make sense. How would you do it? • Students may group the plantlike, sessile organisms (the plant, seaweed, and mushroom) together, grouping the others as animals. • 3. Decide on your categories and write each on a sheet of paper. Next to each category, write the defining characteristics of that category. Then, write in the organisms that fall into each category. • Remind students that organizational systems are human-made, and there are no right or wrong ones. Some, however, are more usefulthan others.

30. Interest Grabber Answers Section 2 Answers • 1. Do you think roses and orchids are closely related? Explain your answer. • Students may say that their different growth habits and inability to hybridize indicate that they are not closely related. • 2. Now, apply the same logic to dogs. Different breeds of dogs—such as a Labrador retriever and a collie—can breed and produce offspring. So what is the difference between the rose-orchid combination and the Lab-collie combination? • Students may know that all domestic dogs are a single species. • 3. What defines a species? Is appearance important? What other factors might be considered? • Students may suggest that a species is defined by its members’ ability to interbreed, regardless of appearance.

31. Interest Grabber Answers Section 3 Answers • 1. What categories could you use to organize your count of vehicles? • Students’ answers may include, type of vehicle, color, age, or manufacturer. • 2. Look at your list of categories. Are all of them equally useful? • Students may suggest that the usefulness of the criteria depends on the intent of the study. • 3. Is there more than one valid and useful way to organize living things? • Students should conclude that the same set of living things could be categorized in several ways, depending upon the criteria used.

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