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Taxonomy Is the branch of biology that names and classifies species according to a system of broader and broader groups Species Genus Family Order Class Phylum Kingdom Domain Ursus americanus (American black bear) Ursus Ursidae Carnivora Mammalia Chordata Animalia Figure 1.14 Eukarya 1 • Over a million species named (so far) • More identified every week! • Est. 2-20 Million left to find? • Why bother with a naming “system”? Need to organize information, make sense of it, look for similarities and differences • Groups organisms based on: Anatomy, Genetics, andEvolutionary history (“relatedness”) 2 (384–322 BC) the Greek philosopher was the first to attempt to classify all living things, and some of his groups are still used today, like the vertebrates and invertebrates, which he called “animals with blood and without blood”. (Karl von Linne) 1707-1778, was a Swedish botanist, physician, and zoologist, who formalized the modern system of naming organisms called , in Systema Naturae (1758) • He is known by the epithet “Father of Modern Taxonomy". 3 • 3 Domains • 6 Kingdoms • Phylum (“Division” for plants) • Class • Order • Family • Genus • Species 4 5 – Distinguished based on biochemical evidence (differences in rRNA, genes) – Domains Archaea and Bacteria are unicellular organisms lacking membrane-bound organelles like nuclei (Prokaryotes) – Domain Eukarya is organisms whose cells have nuclei (Plants, Animals, Fungi and Protists) 6 • Prokaryotes – Single celled, DNA/RNA but no nucleus, few, simple organelles, cell walls) • Kingdom Archaebacteria – Found in extreme environments (similar to those of early earth) – Complex metabolic ability (many are chemosynthetic) – First organisms similar to Archaea? 7 – Unicellular – Prokaryotic cells (no nucleus, few, simple organelles, cell walls) – Found almost everywhere – More of them than any other living thing – Some are autotrophs, some heterotrophs (depends on the species) – Some are pathogens (cause diseases) – Most are harmless and many are vital to human well being • Decompose our wastes • Make vitamins in our guts • Producing certain products that we use (yogurt, cheese) 8 – Most are one-celled organisms (ex: amoeba, paramecium, euglena) – A few are multicellular (ex: kelp, seaweed) – May be producers or consumers (or both); depends on the species – Some are very “plant-like”, others are very “animal-like” 9 – Eukaryotic cells – Have cell walls for support (chitin) – Most are multicellular, with a few unicellular species (yeasts) – Heterotrophic; enzymatically digest and absorb nutrients – Mostly decomposers (important for ecosystem nutrient cycling); a few are parasitic 10 – All are multicellular – Composed of eukaryotic cells with a cell wall made of cellulose – Photosynthetic autotrophs, chlorophyll – Important producers of glucose “fuel” for entire ecosystem 11 All are multicellular (sponges to humans) Composed of complex, eukaryotic cells, no cell walls (flexible, for mobility) All are heterotrophic consumers 12 Classification of Living Things • Within Kingdoms, organisms are sorted into Phylum, Class etc. • At species level organisms so closely related they can interbreed • Scientific name = Genus and species names (binomial nomenclature ex. Felis catus, Drosophila melanogaster, Homo sapiens • Genus includes other similar species ex. F. leo and F. tigris or Quercus rubra, Quercus alba • Genus ALWAYS starts with cap, species lower case • Genus and species names are always either underlined or italicized 13 Scientific nomenclature shows both anatomical similarity and evolutionary history 14