Chapter 18: Classification

1. Why Classify? Biologists have identified and named about 1.5 million species and estimate that anywhere between 2 and 100 million additional species have yet to be discovered. To study the diversity of life, biologists use a classification system to name organisms and group them in a logical manner (taxonomy). Chapter 18: Classification

2. Referring to organisms by their common names can be quite confusing. (ex: buzzard in UK = hawk, buzzard in U.S. = vulture) • Catfish, starfish, seahorse, jellyfish…. What are they? • A Swedish botanist named Carolus Linnaeus developed a two-word naming system called binomial nomenclature.

3. Linnaeus’s System of Classification

4. Section 18.1 – Finding Order in Diversity • Good classification does two things: • Organized into groups that have biological similarities • Organize according to unique/important characteristics/how related

5. Binomial Nomenclature (naming system) • 2 part scientific name • Genus species • Italicize letters • Genus Capitalized; species lowercase • EX. Panthera pardus panther or leopard (genus species) same species, different common name)

6. FYI: The genus Ursus contains 5 other kinds of bears, including polar bears, black bears, and brown bears. • The polar bear, for example has the scientific name Ursus maritimus. • The second part of a scientific name – maritimus, is unique to each species within the genus. • Often, this part of the name is a Latinized description of some important trait or an indication of where it lives. • For example, the Latin word maritimus refers to the sea, where polar bears live. • Another example – humans: Homo sapiens

7. Frogs & Toads of Illinois FYI • American toad (Bufo americanus) • Blanchard’s cricket frog (Acris crepitans blanchardi) • Bullfrog (Rana catesbeiana) • Cope’s gray treefrog (Hyla chrysoscelis) • Crawfish frog (Rana areolata) • Eastern gray treefrog (Hyla versicolor) • Eastern spadefoot (Scaphiopus holbrooki) • Fowler’s toad (Bufo fowleri) • Green frog (Rana clamitans) • Northern leopard frog (Rana pipiens) • Pickerel frog (Rana palustris) • Plains leopard frog (Rana blairi) • Southern leopard frog (Rana sphenocephala) • Spring peeper (Hyla crucifer) • Western chorus frog (Pseudacris triseriata) • Wood frog (Rana sylvatica)

8. Section 18.2 – Modern Evolutionary Classification • Traditional classification system is that scientists relied on body structure comparison • Organisms that are quite different from each other evolve similar body structures. • Ex: crabs, barnacles, and limpets

9. Traditional Classification vs. Evolutionary Classification Appendages Conical Shells Crustaceans Gastropod Crab Crab Limpet Limpet Barnacle Barnacle Molted exoskeleton Segmentation Tiny free-swimming larva CLASSIFICATION BASED ON VISIBLE SIMILARITIES CLADOGRAM

10. Evolutionary Classification • Darwin’s ideas about descent with modification have given rise to the study of phylogeny, or evolutionary relationships among organisms. Used today.

11. Classification Using Cladograms • To refine the process of evolutionary classification, many biologists now use a method called cladistic analysis. • Uses derived characters – unique characteristics that appear in recent organisms.

12. Cladograms • Derived characters can be used to construct a cladogram, a diagram that shows the evolutionary relationships among a group of organisms.

13. Cladogram of Animal Kingdom Chordates Echinoderms Arthropods Annelids Mollusks RadialSymmetry Roundworms Flatworms Pseudocoelom Deuterostome Development Cnidarians RadialSymmetry Coelom Protostome Development Sponges Three Germ Layers;Bilateral Symmetry Tissues Multicellularity Single-celled ancestor

14. Similarities in DNA & RNA • The genes of many organisms show important similarities at the molecular level. These similarities are used to classify. • EX. Humans and yeast both have a gene that codes for myosin (a protein in our muscles) — an indicator that humans and yeast have a common ancestor.

15. DNA Evidence Example • In the traditional classification system, African vultures and American vultures were classified together, but DNA analysis has revealed that American vultures are actually more closely related to storks. • Based on DNA analysis, we know that chimpanzees are our closest living relatives (humans and chimps share 98.5% same DNA).

16. Molecular Clocks • Comparisons of DNA can show how closely related organisms are. • A model known as a molecular clock uses DNA comparisons to estimate the length of time that two species have been evolving independently.

17. Neutral mutations (those that have no effect on phenotype) accumulate in the DNA of different species. • The more similar the neutral DNA (genes) the more closely related the organisms.

18. 18-3 Kingdoms and Domains The Tree of Life evolves Linnaeus’s 2-kingdom classification was eventually revised to include 6 kingdoms: Eubacteria, Archaebacteria, Protista, Fungi, Plantae, and Animalia

19. The Three Domain System Molecular analyses have given rise to a new taxonomic category called the Domain Domain- a more inclusive category than any other—larger than a kingdom 1. Bacteria- corresponds to the kingdom Eubacteria 2. Archaea- corresponds to the kingdom Archaebacteria 3. Eukarya- corresponds to the kingdoms protists, fungi, plants, and animals

20. Domain Bacteria Unicellular and prokaryotic Thick, rigid cell walls with peptidoglycan (gram +) Ecologically diverse (some are free-living while others are parasites, some need oxygen while others are killed by it) Autotrophic or heterotrophic EX. Streptococcus, E. coli, Syphilis, Chlamydia, etc.

21. DomainArchaea “ancient bacteria” Unicellular and prokaryotic Live in extreme environments (volcanic hot springs, black organic mud deprived of oxygen, and brine pools) Cell walls lack peptidoglycan and cell membranes contain unusual lipids not found in any other organism (gram -) Autotrophic or heterotrophic EX. Methanogen, halophiles

22. Domain Eukarya Consist of all organisms with a nucleus and is organized into the 4 remaining kingdoms 1. Protista “taxonomic misfits” Don’t fit into other categories. Most single-celled; some colonial, microscopic ¼ inch. Neither plant nor animal. Some photosynthetic; others heterotrophic Most Diverse Group- Amoeba (some cause dysentery; others harmless) paramecium, slimemolds (fungus-like), diatoms (plant-like), giardia (animal-like parasite), other diseases caused are sleeping sickness and malaria. Sexual and asexual reproduction

23. 2. Fungi Produce foods such as Cheese, soy sauce, mushrooms Cell walls of chitin Most multicellular; some unicellular/ sexual and asexual reproduction Heterotrophic—feed on dead organic matter (saprobes) Fermentation to make alcohol Produce antibiotics Produce chemicals used in soaps and plastics EX. mushrooms, yeast, potato blight, ringworm, mildew

24. 3. Plantae Cell walls of cellulose, Contain chloroplasts, Multicellular, Autotrophic, Nonmotile Most are terrestrial and have adapted in the following ways: Control water loss Vascular tissue- move materials (Xylem-water and Phloem-food) Protective packaging for gametes and embryos (pollen, eggs, seeds) Ex: seed plants (angiosperms and gymnosperms) seedless plants (mosses, ferns, horsetails)

25. 4. Animalia Multicellular, Heterotrophic, lack cell walls Great diversity and many species exist in nearly every part of the planet. Phylums listed below for Kingdom Animalia: Phylum Porifera – sponges Phylum Cnidaria – hydras, jellyfish, sea anemone, corals Phylum Platyhelminthes – flatworms (planaria, flukes, tapeworms)

26. Phylum Nematoda – roundworms (nematodes) • Phylum Mollusca – mollusks (snails, squid, sea slugs, oyster) • Phylum Annelida- segmented worms (earthworms, leeches, marine) • Phylum Arthropoda – Insects, crustaceans, spiders, mites, millipedes, etc • Phylum Echinodermata- sea stars, sea cucumbers, sand dollars, brittle stars • Phylum Chordata- chordates or “vertebrates” during all or part of life (mammals, birds, reptiles, amphibians, fish, tunicates, etc.)

27. Key Characteristics of Kingdoms and Domains Classification of Living Things Fungi Eukaryote Cell walls of chitin Most multicellular; some unicellular Heterotroph Mushrooms, yeasts Plantae Eukaryote Cell walls of cellulose; chloroplasts Multicellular Autotroph Mosses, ferns, flowering plants DOMAIN KINGDOM CELL TYPE CELL STRUCTURES NUMBER OF CELLS MODE OF NUTRITION EXAMPLES Animalia Eukaryote No cell walls or chloroplasts Multicellular Heterotroph Sponges, worms, insects, fishes, mammals 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 Eukarya 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

28. Questions 1. How is a cladogram used? 2. How is a dichotomous key used? 3. How do you name organisms?