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Introduction to Taxonomy: Organizing and Classifying Organisms

Discover the history and principles of taxonomy, the science of classifying organisms. Learn about Carolus Linnaeus and his development of the hierarchical system of classification, as well as the use of binomial nomenclature. Explore the levels of classification and the importance of phylogeny in modern taxonomy.

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Introduction to Taxonomy: Organizing and Classifying Organisms

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  1. Taxonomy

  2. Taxonomy • Branch that names and groups organisms according to characteristics and evolutionary history. • Aristotle-animals or plants • 15th/16th centuries-use of common names presented problems: • Varied from one locale to next. • May not describe species accurately.

  3. Carolus Linnaeus • Developed hierarchy (ranking system) using organism’s morphology (form/structure) for classifying organisms. • System of groups (taxa-taxon). • Broadest and most general taxa to smallest and most specific taxa.

  4. How Written: • Binomial nomenclature-two names for every organism. • 1st-Genus-relatively small group of organisms to which a particular type of organism belongs. • 2nd-Species (species identifier)-usually a Latin description of some important characteristic of organism. • Capitalize Genus but not species identifier. • Print name in Italics or underline them

  5. Can abbreviate genus Acer rubrum – red maple tree Acer- Latin name for Maple (genus) rubrum- Latin word for Red (species) A. rubrum Humans are named Homo sapiens Homo-large brain/upright posture sapiens-our intelligence/ability to speak H. sapiens

  6. Levels of Classification • Domain • Kingdom • Phylum (Division-in plant kingdom)  • Class • Order  • Family • Genus • Species • King Philip Came Over For Grandma’s Soup. • Botanist sometimes split species into subsets (varieties).  • Bacteria are also broken into subsets (strains).

  7. Each vertical line represents a different kind of organism.  Ancestral individuals are indicated by vertical lines near the top of the diagram and closely related kinds are linked to these by horizontal lines.

  8. Modern taxonomist consider phylogeny (evolutional history of organism) • May consider its: • Morphology (study of animal form). • Chromosomal characteristics. • Molecular biology: • Closely related species have similar DNA and, therefore, similar proteins. • More amino acids/nucleotide base sequences that are shared by two species, more closely related they are. • Fossil record. • Embryological development: • Though adults of certain species may look different, larval form of one species may show a resemblance to the adult of another species-suggests a common ancestor.

  9. Homework: Read 20.1, pp. 481-489 Do Worksheets, pp. 73-74 http://www.glencoe.com/sec/science/biology/bio2000/pdfs/bdol17-1.pdf

  10. Two approaches, both based on hypothesis • Systematics-phylogenetic tree (family tree): • Relationships thought to exist among groups of organisms. • Fan model can be used (pp. 492-3 in book).

  11. CladisticsCladograms • Sharedderivedcharacters (certain features) to establish evolutionary relationships: • Feature that apparently evolved only within the group under consideration (like bird feathers-since no other animals have, safe to assume that feathers evolved within bird group and not inherited from some distant bird ancestor). • Cladogram-branching diagram shows divergence of two groups from common ancestors w/emergence of lineage possessing new set of derived traits.

  12. Cladistics is based on three principles: • Groups of organisms are descended from a common ancestor. • At each node (divergence of a population), there are two branching lines of descendants. • Evolution results in modifications of characteristics over time.

  13. Cladogram of Six Kingdoms and Three Domains

  14. Relationship among the six kingdoms

  15. Norns belong to the genus Norno and can be divided into eight species that are generally located in specific regions of the world. Use dichotomous key to identify the norns below. Write their complete scientific name (genus + species) in the blank. 1. Has pointed ears ............................go to 3 Has rounded ears ...............................go to 2 2. Has no tail .......................................Kentuckyus Has tail ............................................... Dakotus 3. Ears point upward ...........................go to 5 Ears point downward ..........................go to 4 4. Engages in waving behavior .......... Dallus Has hairy tufts on ears ........................Californius 5. Engages in waving behavior .......... WalaWala Does not engage in waving behavior ..go to 6 6. Has hair on head .............................Beverlus Has no hair on head (may have ear tufts) ..go to 7 7. Has a tail ..........................................Yorkio Has no tail, aggressive .........................Rajus Dichotomous Keys

  16. Homework: Read 20.2, pp. 490-498 pp. 499-501, #1-20, 22, 31, Assessing Knowledge & Skills, #1-3 Do Worksheets, pp. 75-76 Do quiz and submit as before. http://www.glencoe.com/qe/science.php?qi=2530

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