Taxonomy

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Taxonomy

  1. 1. Taxonomy, Classification, and Identification Karl Hagenbuch Department of Biological Sciences San Antonio College
  2. 2. Taxonomy = the study of naming, describing and classifying organisms, including the rules, theories, principles and procedures Taxon = a group of organisms recognized at any level of a taxonomical hierarchy (e. g. Family, Class)
  3. 3. Classification = the orderly arrangement of organisms into a hierarchal system that is derived from an accumulation of information about the individual organisms, the end result expressing an interrelationship Why? Because it provides humans with a means to address organisms and their relationships to one another Because it allows humans to make inferences about unfamiliar organisms Because it is in our nature
  4. 4. Classification Systems: Artificial = based on obvious or convenient items of information called characters (e.g. flower color, locality). Natural = based on morphological features that give the sense of correlation with those of another organism. (e.g. trees, grasses) Phylogenetic = based on the proposed lineage derived from a wide variety of information.
  5. 5. Aristotle <ul><li>Greek Philosopher </li></ul><ul><li>First to propose a system of classification </li></ul><ul><li>Scala Naturalae </li></ul><ul><li>Two types of animals: </li></ul><ul><li>With blood </li></ul><ul><li>Without blood </li></ul>
  6. 6. Theophrastus <ul><li>Greek Philosopher </li></ul><ul><li>Father of plant taxonomy </li></ul><ul><li>Classification of plants was based on: </li></ul><ul><li>Mode of generation </li></ul><ul><li>Locality </li></ul><ul><li>Size </li></ul><ul><li>Usefulness </li></ul>
  7. 7. Carl von Linné Carolus Linnaeus Swedish botanist, zoologist, and physician First to illustrate the usefulness of binomial nomenclature Developed the modern taxonomic hierarchy Binomial Nomenclature Modern Hierarchy (Biological Classification) Domain – Eukarya Kingdom – Animalia Phylum – Cordata Class – Mammalia Order – Primates Family – Hominidae Genus – Homo Species – Homo sapiens Specific epithets: Descriptives – Quercus macrocarpa = Oak with big fruit Honorifics – Quercus buckleyi = Oak named for Mr. Buckley Localities – Quercus virginiana = Oak first described in Virginia = a two-word name consisting of a generic name and a specific epithet Current system recognizes 3 Domains: Eukarya: Kingdom Animalia Kingdom Plantae Kingdom Fungi Archaea & Bacteria The previously recognized Kingdoms of Protista & Monera have been disolved
  8. 8. Phylogenetic Classification = the evolutionary history of a species or group of species Typically represented as a phylogenetic tree (cladogram) a branching diagram showing the evolutionary relationships among various biological species or other taxa that are believed to have a common ancestor The Pylogenetic Tree
  9. 10. Time
  10. 11. Species 1 Species 2 Species 3
  11. 13. Plant Classification Current classification systems follow the recognized taxonomic hierarchy, however, there is always some disagreement as to the membership requirements of various taxa Lumpers & Splitters The Core <ul><li>Non-vascular land plants </li></ul><ul><li>reduced plants that lack vascular (circulatory) tissues </li></ul><ul><li>they neither have flowers nor produce seeds </li></ul><ul><li>reproductive unit is a spore </li></ul><ul><li>Ferns and fern allies </li></ul><ul><li>plants with vascular (circulatory) tissues </li></ul><ul><li>they neither have flowers nor produce seeds </li></ul><ul><li>reproductive unit is a spore </li></ul><ul><li>Gymnosperms </li></ul><ul><li>plants with vascular (circulatory) tissues </li></ul><ul><li>they lack flowers </li></ul><ul><li>reproductive unit is a seed produced on scales in a cone-like structure </li></ul><ul><li>Angiosperms </li></ul><ul><li>plants with vascular (circulatory) tissues </li></ul><ul><li>they produce flowers </li></ul><ul><li>reproductive unit is a seed produced within an enclosed ovary </li></ul>
  12. 14. Identification = the assigning of an existing name to an unknown organism Methods Expert assistance – local university, school, museum Comparison method – guide books, internet Dichotomous key – local manuals, floras
  13. 15. Dichotomous Key Keys based on a sequence of pairs of contrasting statements The user chooses the statement that better describes the plant in question Each time a choice is made a number of plants are eliminated Eventually the number of possible identifications is reduced to one
  14. 16. Dichotomous Key 1. Growth habit an herb 1. Growth habit a vine, shrub or tree . . . . . . . . . . . . 2 . . . . 4 4. Growth habit a vine 4. Growth habit a shrub or tree . . . . . . . . . . . . 5 . . . . . . . 7 7. Growth habit a shrub 7. Growth habit a tree . . . . . . . . . . . . 8 . . . . . . . . . . . . 30
  15. 17. Dichotomous Key 30. Leaf arrangement opposite 30. Leaf arrangement whorled or alternate . . . . Fraxinus . 31 31. Leaves simple 31. Leaves compound . . . . . . . . . . . . . . . 32 . . . . . . . . . . . . 44 32. Venation palmate 32. Venation pinnate or reticulate . . . . . . . Washingtonia . . . . . . 33
  16. 18. Dichotomous Key 33. Margin entire 33. Margin toothed . . . . . . . . . . . . . . . 34 . . . . . . . . . . . . . . 39 34. Lobes present 34. Lobes absent . . . . . . . . . . . . . . . 35 . . . . . . . . . . . . . . 37 35. Blades palmately lobed 35. Blades pinnately lobed . . . . . Platanus . . . . . . . . . 36
  17. 19. Dichotomous Key 36. Lobes rounded 36. Lobes pointed . . . Quercus macrocarpa . . . . . Quercus buckleyi
  18. 20. Thank You It is both an honor and pleasure to speak before the Master Naturalist I wish you all continued success

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