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Classification

Classification. Taxonomy Science of grouping organisms according to their presumed natural relationships. Artificial. May change with new evidence. History of Classification. Aristotle. Either plant or animal. Animals where they lived. Land Dwellers. Water Dwellers. Air Dwellers.

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Classification

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  1. Classification

  2. Taxonomy Science of grouping organisms according to their presumed natural relationships Artificial May change with new evidence

  3. History of Classification

  4. Aristotle Either plant or animal

  5. Animals where they lived Land Dwellers Water Dwellers Air Dwellers

  6. Plants based on stem differences Herbs Shrubs Trees

  7. 18th Century New discovered organisms didn’t fit Used Latin Descriptions - Cumbersome

  8. Common Names • Everyday name given to organisms • Don’t describe accurately • Same name for two organisms • May have more than one common name

  9. Carolus Linneaus Swedish Naturalist – 1707 -1778 Grouped organisms into a hierarchy Developed system called Binomial Nomenclature

  10. Linneaus’ Hierarchy Kingdom Phylum Class Order Family Genus Species

  11. Binomial Nomenclature Means “two names” Uses Genus and Species Also called Scientific Name

  12. Rules for Scientific Names • Describes organism, its range, or honors another scientist • Name is always Latinized • Genus – capitalized; Species – Lower Case • Always italicized or underlined

  13. Levels of Classification with Human Taxonomy • Kingdom – Animalia • Phylum – Chordata • Class – Mammalia • Order – Primates • Family – Hominidae • Genus – Homo “Man” • Species – Sapiens “Wise One”

  14. The Taxonomist’s Subgroups Subspecies – morphologically different; geographically separated Variety – morphologically different; not geographically separated Strain – biochemically dissimilar group in a species; microorganisms

  15. Domains • Bacteria – Kingdom Eubacteria • Archea – Kingdom Archaebacteria • Eukarya – Kingdoms Protista, Fungi, Plantae, and Animalia

  16. Evidence used in Classification • Comparative Morphology (Anatomy) • Embryological Evidence • Genetic Similarities • Biochemical Comparisons • Physiological Studies

  17. Comparative Morphology • Based on physical features • Looks at structural similarities • May or may not be completely accurate • Identification often uses a Dichotomous Key • Set of written choices leading to organism’s name • Branches; selections become more specific

  18. Embryological Evidence • Usually used for upper categories – Phylum, Class, etc. • Looks at origin of body organs • Homologous Organs – common origin, similar function – bat’s wing, human’s arm • Analogous Organs – Different origin, similar function – insect’s wing vs bird’s wing

  19. Genetic Similarities • Looks at DNA sequences – related species have more similarities • Comparison of Karyotypes – picture of organism’s chromosomes • Chromosome counts • Chromosome shapes

  20. Biochemical Comparisons • Comparisons of amino acid sequences in common proteins in different species • More similarities indicate closer relationship

  21. Physiological Studies Useful in Bacterial Classification Looks at what chemical bacteria may use as food May look the same but have different physiologies

  22. Phylogeny Evolutionary history of a species Uses evidence of probable evolutionary relationships Phylogenetic Tree (Cladogram) – model of inferred evolution

  23. Phylogenetic Tree • Species at branch ends – most recently evolved organisms • Main Branches and Trunk – organisms which gave rise to more recent organisms • Close branches imply close evolutionary history

  24. Biosystematics • Study of reproductive compatibility and gene flow • Reproductive compatibility used to infer evolutionary relationship • Studies speciation – evolution of one species into two new species

  25. Kingdom Classifications Two Kingdoms Three Kingdoms Plants Animals Protists Plants Animals

  26. Kingdom Classifications Four Kingdoms Five Kingdoms Plants Animals Protists Monera Fungi Plants Animals Protists Monera

  27. Kingdom Classifications Six Kingdoms Plants Animals Protists Fungi Eubacteria Archaebacteria

  28. Criteria for Defining Kingdoms • Cell Structure – Prokaryote or Eukaryote • Number of Cells – Unicellular or Multicellular • Nutrition – Autotrophs or Heterotrophs • Reproduction – Asexual or Sexual

  29. Kingdom Characteristics Archaebacteria Eubacteria Prokaryotic Unicellular – Cell Walls with peptidoglycan Autotrophs and Heterotrophs Asexual/Sexual Typical Bacteria Prokaryotic Unicellular – Cell Walls without peptidoglycan Autotrophs and Heterotrophs Asexual/Sexual Live in extreme environments

  30. Kingdom Characteristics Protista Fungi Eukaryotic Multicellular some Unicellular Heterotrophic by Absorption Sexual/Asexual Mostly terrestrial, some aquatic Eukaryotic Unicellular some Multicellular Autotrophs and Heterotrophs Asexual/Sexual Aquatic or Moist Habitats

  31. Kingdom Characteristics Plantae Animalia Eukaryotic Multicellular Heterotrophic by ingestion Sexual/Asexual (lower species) Aquatic and terrestrial Most move about Eukaryotic Multicellular Autotrophic Sexual/Asexual Aquatic and terrestrial Usually remain in one place

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