Classification of Organisms

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Classification of Organisms

• Chapter 16

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Why is it important for organisms to be
scientifically classified?

• 1. To avoid confusion that would result from only
  using vernacular names
• Vernacular name (aka common name) The
  nonscientific name used by the general public.
  (i.e. pine tree, daisy, etc)
• Often different vernacular names for the same
  plant. (Vernacular names vary person to person,
  region to region, and country to country.)
• One common name could represent many different
  species (i.e. daisy or sunflower, pine)

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Why is it important for organisms to be
scientifically classified?

• 2. Classification systems reflect hypotheses
  about evolutionary relationships between
  organisms.
• i.e. the potato, tomato, pepper, and tobacco are
  all in the same family because they are
  evolutionarily related.
• i.e. Just because a group of plants has, say, red
  fruit, doesnt mean theyre all in the same
  family even though they share that
  characteristic. (i.e. strawberry, tomato,
  cranberry are all in different families). So a
  lot of thought and research goes into determining
  which plants are truly related genetically.

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Systematics Taxonomy

• Systematics The scientific study of the
  evolutionary relationships between organisms.
• Taxonomy the naming and classifying of species.
  (from the Greek taktos, ordered, and onoma,
  name).
• (Taxonomy is included within the study of
  systematics.)

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What determines how it is classified?

• Systematists use a variety of characters to
  classify organisms. Some include
• Morphology the form and structure of an organism
  (i.e. presence/absence of flowers, form and
  structure of flowers and fruit, microscopic
  design on seed coats and pollen, etc)
• Life stages (i.e. embryo development, means of
  reproduction, etc)
• Molecular data (i.e. genetic material such as
  DNA)

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Modern Taxonomy

• Throughout time, different methods of naming and
  classifying plants have been attempted, but Carl
  Linnaeus binomial system of classification was
  the one that stuck.
• Carl Linnaeus (1707-1778) was a Swedish professor
  of botany and medicine.

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Binomial Nomenclature

• Linnaeus began assigning two names (bi two,
  nomial name) to plants.
• Consists of a Genus and species name, usually
  written in Latin.
• These binomials, usually summarized the general
  characteristics of the plant
• i.e. Digitalis purpurea (foxglove)
• Digitalis derived from Latin word for finger
  (flowers resemble thimbles)
• purpurea Latin for purple.

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What is the correct way to write scientific
binomials?

• Always italicized or underlined
• Genus (the first name) is always capitalized.
• Species epithet (a.k.a. specific epithet) is the
  second name and is always lowercase.
• So when referring to a species, you need to
  refer to the whole binomial, not just the
  species epithet
• i.e. Malus domestica vs. Musca domestica, these
  are two totally different species that share the
  same species epithet

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Liriodendron tulipifera (Tulip tree, aka
Yellow Poplar, White Poplar, Whitewood, etc
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Organisms are classifiedinto a hierarchy of
categories

• Domain
• Kingdom
• Phylum (some botanists use Division)
• Class
• Order
• Family
• Genus
• Species
• Do Kings Play Chess On Fine Grained Sand?

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The Major Lineages of Life
(Prokaryotes)
(Prokaryotes)
Prokaryotic Cells do not have a membrane-bound
nucleus Eukaryotic Cells have a membrane
around nucleus
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• Every living thing consists of at least one cell.
  
• Based on the characteristics of these cells, they
  are categorized into one of 3 domains.
• Two of the 3 consist of microscopic organisms

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• Cladogram a tree-like branching diagram
  that shows evolutionary relationships.

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Kingdom PlantaeWhat is a Plant?

• Retention of embryo
• Make organic molecules by photosynthesis
• Roots that provide anchorage and absorb water and
  mineral nutrients from the soil.
• Most have stems, leaves, cuticles, and stomata
• ie Mosses, ferns, trees, grasses, pine trees,
  and flowers belong to the Plantae Kingdom

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Simplified cladogram with major distinguishing
characteristics
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What distinguishes Plants from Algae?

• True plants (i.e. Kingdom Plantae) are
  Embryophytes
• After fertilization, the zygote develops into a
  multicellular embryo while still enclosed in the
  female reproductive structure.

• Definitions
• Fertilization union of sperm and egg
• Zygote cell resulting from the union of the
  sperm nucleus and egg nucleus (nucleus contains
  the genetic material, DNA)
• Embryo baby plant that hasnt left mom yet. It
  even has an umbilical cord and belly button!

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ALGAE are cool, but theyre not plants!
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Simplified cladogram with major distinguishing
characteristics
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Vascular tissue

• Vascular tissue plant tissue that transports
  water, nutrients, and hormones throughout the
  plant. (like our veins do!)
• Provide strong support, enabling stems to stand
  upright and grow tall on land.
• Ferns have vascular tissue, but produce no seeds,
  only spores.

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Simplified cladogram with major distinguishing
characteristics
Va
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Seeds

• A Seed consists of a plant embryo packaged with a
  food supply within a protective covering.

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Simplified cladogram with major distinguishing
characteristics
Va
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