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Classification Chapter 18 Key Concepts •How living things are organized for study •What dichotomous classification is •What binomial nomenclature is •What Linnaeus’s system of classification is 18-1 Interest Grabber 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. 18–1 Finding Order in Diversity Why Classify? Assigning Scientific Names Early efforts at naming organisms Binomial nomenclature Linnaeus’s System of Classification Kingdom Phylum Class Order Family Genus Species Q: What is this animal called? •Confusing names • • • • • common Panther Puma Mountain Lion Catamount Cougar A: All of the Them! •Common Name depending on location • • • • • Panther Puma Mountain Lion Catamount Cougar •Scientific • Name Puma concolor (formerly Felis concolor – changed in 1993) Note – in Scientific Name, only the first term is capitalized Section 18-1 Linnaeus’s System of Classification You need to know these! Think of a mnemonic device to help you remember the order! “Please Excuse My Dear Aunt Sally” “King Phillip Cuts Open Five Green Snakes” Choose something that has meaning to you “Kings Play Colorado On Friday. Go! Score!” Kingdom Phylum Class Order Family Genus Species Section 18-1 Linnaeus’s System of Classification Kingdom – a group of related phyla **Linnaeus only recognized two kingdoms – Plant & Animal** Phylum – a group of related classes Class – a group of related orders Order – a group of related families Family – a group of related genera Genus – a group of related species Species Scientific name is always “Genus species” Kingdom Phylum Class Order Family Genus Species Section 18-1 Grizzly bear Black bear Giant panda Red fox Coral Sea star Abert squirrel snake KINGDOM Animalia PHYLUM Chordata CLASS Mammalia ORDER Carnivora Classification of Ursus arctos FAMILY Ursidae GENUS Ursus SPECIES Ursus arctos What are some ways in which these animals are similar, and what are some ways they are different? What are some ways in which these animals are similar, and what are some ways they are different? 18-2 Interest Grabber 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. 18-2 Interest Grabber Do you think roses and orchids are closely related? Explain your answer. 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? What defines a species? Is appearance important? What other factors might be considered? 18-2 Modern Evolutionary Classification Which Similarities Are Most Important? Evolutionary Classification Classification Using Cladograms Similarities in RNA and DNA Molecular Clocks Section 18-2 Traditional Classification Appendages Crab Conical Shells Barnacle Limpet Crustaceans Crab Gastropod Barnacle Limpet Molted exoskeleton Segmentation Tiny free-swimming larva CLASSIFICATION BASED ON VISIBLE SIMILARITIES CLADOGRAM Section 18-2 Traditional vs. Cladogram Appendages Crab Conical Shells Barnacle Limpet Crustaceans Crab Gastropod Barnacle Limpet Molted exoskeleton Segmentation Tiny free-swimming larva CLASSIFICATION BASED ON VISIBLE SIMILARITIES CLADOGRAM 18-3 Interest Grabber 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. 18-3 Interest Grabber What categories could you use to organize your count of vehicles? Look at your list of categories. Are all of them equally useful? Is there more than one valid and useful way to organize living things? 18-3 Kingdoms and Domains The Tree of Life Evolves The Three Domain System Domain Bacteria Domain Archaea Domain Eukarya Protista Fungi Plantae Animalia Section 18-3 Living Things Prokaryotic cells are characterized by Eukaryotic cells and differing Important characteristics which place them in Cell wall structures such as Domain Eukarya which is subdivided into which place them in Domain Bacteria Domain Archaea which coincides with which coincides with Kingdom Eubacteria Kingdom Archaebacteria Kingdom Plantae Kingdom Fungi Kingdom Protista Kingdom Animalia Cladistic Analysis Analysis of the order in which derived characteristics appeared Cladogram – diagram that shows the evolutionary relationships among a group of organisms based on these characteristics Derived Characteristics – a characteristic that arises as a lineage of organisms evolves over time DNA analysis determined evolutionary relationships Similar genes are evidence of common ancestry American Vultures and Storks are classified together based on DNA Molecular Clocks Comparison of DNA determines when species diverged and began to evolve independently “Neutral mutations” – insignificant genetic changes that accumulate at a steady rate are measured and compared from species to species The degree of disimilarity indicates how long ago the two species shared a common ancestor 5 Kingdom Classification Monera – bacteria, Protista – unicellular, animal or plant like, such as algae Eukaryotes, *previously classified as plants* Plantae eukaryotes Fungi – mushrooms prokaryotes eukaryotes Animalia eukaryotes Six Kingdoms Monera Kingdom is too general and composed of two distinct groups of bacteria Differences are as great as those between animals and plants Six Kingdom classification system separates monera into two kingdoms: Eubacteria Archaebacteria Protista Fungi Plantae Animals Key Characteristics of Kingdoms & Domains Classification of Living Things DOMAIN Bacteria Archaea KINGDOM Eubacteria Archaebacteria CELL TYPE Eukarya Protista Fungi Plantae Animalia Prokaryote Prokaryote Eukaryote Eukaryote Eukaryote Eukaryote Cell walls with peptidoglycan Cell walls without peptidoglycan Cell walls of cellulose in some; some have chloroplasts Cell walls of chitin Cell walls of cellulose; chloroplasts No cell walls or chloroplasts Unicellular Unicellular Most unicellular; some colonial; some multicellular Most multicellular; some unicellular Multicellular Multicellular MODE OF NUTRITION Autotroph or heterotroph Autotroph or heterotroph Autotroph or heterotroph Heterotroph Autotroph Heterotroph EXAMPLES Streptococcus, Escherichia coli Methanogens, halophiles Amoeba, Paramecium, slime molds, giant kelp Mushrooms, yeasts Mosses, ferns, flowering plants Sponges, worms, insects, fishes, mammals CELL STRUCTURES NUMBER OF CELLS Three Domain System Classifications and divisions are based on evidence from molecular clock models Organisms are grouped according to how long they have been evolving independently (1) Domain Bacteria – Corresponds to Kingdom Eubacteria unicellular, prokaryotes, peptidoglycan (protein that gives strength to the cell wall; also important in binary fission (cell reproduction) (2) Domain Archaea – Corresponds to Kingdom Archaebacteria unicellular, prokaryotes; live in the most extreme conditions (low to no O2, brine pools, and volcanic hot springs) No peptidoglycan; contain unusual lipids not found in any other living organisms Three Domain System (cont.) (3) Domain Eukarya – all organisms that have a nucleus (eukaryotes) Protista – members have greatest variety, single celled and multi-cellular, some P/S like algae, some heterotrophic Fungi – Heterotrophs, feed on dead or decaying matter, multicellular mushrooms and unicellular yeasts Plants – multicellular P/S organisms, cell walls contain cellulose Animals – multicellular heterotrophs, no cell walls Cladogram of Six Kingdoms & Three Domains DOMAIN ARCHAEA DOMAIN EUKARYA Kingdoms DOMAIN BACTERIA Eubacteria Archaebacteria Protista Plantae Fungi Animalia
