CHAPTER 18 CLASSIFICATION

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CHAPTER 18 CLASSIFICATION
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Bellringer

• How do you organize your notebook? Is this a
  classification system?

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Bellringer

• What pneumonic do you use to remember the
  classification system?

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• THE NEED FOR SYSTEMS- Biologists use taxonomic
  systems to organize their knowledge of organisms.
  These systems attempt to provide consistent ways
  to name and categorize organisms.

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• The practice of naming and classifying organisms
  is called taxonomy. Taxonomic systems do not use
  common names, which may be confusing because they
  are different in different places.
• Taxonomic systems use categories to organize
  organisms.
• The general term for any one of these categories
  is a taxon (plural, taxa).

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• SCIENTIFIC NOMENCLATURE-All scientific names for
  species are made up of two Latin or Latin-like
  terms. A simpler and more consistent system was
  developed by Swedish biologist Carl Linnaeus in
  the 1750s.

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• Naming Rules
• Linnaeus unique, two-part name for a species is
  now called a scientific name.
• No two species can have the same scientific name.
• When you write the scientific name, the genus
  name should be capitalized and the species
  identifier should be lowercase. Both terms
  should be italicized.

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• THE LINNAEAN SYSTEM-The eight basic levels of
  modern classification are domain, kingdom,
  phylum, class, order, family, genus, and species.

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• PHYLOGENETICS- Grouping organisms by similarity
  is often assumed to reflect phylogeny, but
  inferring phylogeny is complex in practice.
  Phylogeny is the ancestral relationships between
  species.

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• Not all similar characteristics are inherited
  from a common ancestor. Consider the wings of an
  insect and the wings of a bird.
• Through the process of convergent evolution,
  similarities may evolve in groups that are not
  closely related.

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• Similar features may evolve because the groups
  have adopted similar habitats or lifestyles.
• Similarities that arise through convergent
  evolution are called analogous characters.

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• CLADISTICS- Cladistic analysis is used to select
  the most likely phylogeny among a given set of
  organisms.

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CLADISTICS

• Cladistics focuses on finding characters that are
  shared between different groups because of shared
  ancestry.
• Cladistics infers relatedness by identifying
  shared derived and ancestral characters among
  groups, while avoiding analogous characters.

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CLADISTICS

• A shared character is defined as ancestral if it
  is thought to have evolved in a common ancestor
  of both groups.
• A derived character is one that evolved in one
  group but not the other.

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CLADISTICS

• All groups that arise from one point on a
  cladogram belong to a clade.
• A clade is a set of groups that are related by
  descent from a single ancestral lineage.
• Each clade is usually compared with an outgroup,
  or group that lacks some of the shared
  characteristics.

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INFERRING EVOLUTIONARY RELATEDNESS

• Morphological Evidence- Morphology refers to the
  physical structure or anatomy of organisms. An
  important part of morphology in multicellular
  species is the pattern of development from embryo
  to adult.

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INFERRING EVOLUTIONARY RELATEDNESS

• Molecular Evidence- Scientists can now use
  genetic information to infer phylogenies.
  Genetic sequence data are now used widely for
  cladistic analysis.

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INFERRING EVOLUTIONARY RELATEDNESS

• Evidence of Order and Time
• Cladistics can determine only the relative order
  of divergence, or branching, in a phylogenetic
  tree.
• The fossil record can often be used to infer the
  actual time when a group may have begun to
  branch off.
• DNA mutations occur at relatively constant rates,
  so they can be used as an approximate genetic
  clock.
• Scientists can measure the genetic differences
  between taxa and estimate time of divergence.

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• THE THREE-DOMAIN SYSTEM-Today, most biologists
  tentatively recognize three domains and six
  kingdoms. Domain Bacteria is equivalent to
  Kingdom Eubacteria. Domain Archaea is equivalent
  to Kingdom Archaebacteria. Domain Eukarya is made
  up of Kingdoms Protista, Fungi, Plantae, and
  Animalia.

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3 DOMAINS

• Major taxa are defined by major characteristics,
  including
• Cell Type prokaryotic or eukaryotic
• Cell Walls absent or present
• Body Type unicellular or multicellular
  Nutrition autotroph (makes own food) or
  heterotroph (gets nutrients from other organisms)
• Genetics Related groups of organisms will also
  have similar genetic material and systems of
  genetic expression. Organisms may have a unique
  system of DNA, RNA, and proteins.

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3 DOMAINS

• Domain Bacteria
• Bacteria are prokaryotes that have a strong
  exterior wall and a unique genetic system.
• All bacteria are similar in structure, with no
  organelles
• Bacteria are the most abundant organisms on Earth
  and are found in every environment.

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3 DOMAINS

• Domain Archaea
• Archaea have a chemically unique cell wall and
  membranes and a unique genetic system.
• Scientists think that archaea evolved in a
  separate lineage from bacteria early in Earths
  history.

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3 DOMAINS

• Domain Eukarya
• Eukaryotes are organisms composed of eukaryotic
  cells.
• All eukaryotes have cells with a nucleus and
  other internal compartments.
• Also, true multicellularity and sexual
  reproduction only occur in eukaryotes. True
  multicellularity means that the activities of
  individual cells are coordinated and cells
  themselves are in contact.
• Sexual reproduction is an important part of the
  life cycle of most eukaryotes.

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KINGDOMS OF DOMAIN EUKARYA

• Kingdom Plantae
• Almost all plants are autotrophs that produce
  their own food by absorbing energy and raw
  materials from the environment. The process that
  makes food, photosynthesis, occurs in
  chloroplasts.
• The plant cell wall is made of a rigid material
  called cellulose.
• Sexual reproduction is an important part of the
  life cycle of most eukaryotes.

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KINGDOMS OF DOMAIN EUKARYA

• Kingdom Animalia
• Animals are multicellular heterotrophs.
• Animal cells lack a rigid cell wall.

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KINGDOMS OF DOMAIN EUKARYA

• Kingdom Fungi
• Fungi are heterotrophs that are mostly
  multicellular.
• Their cell wall is made of a rigid material
  called chitin.
• Fungi are considered to be more closely related
  to animals than to any other kingdom

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KINGDOMS OF DOMAIN EUKARYA

• Kingdom Protista
• Kingdom Protista is a leftover taxon, so it is
  a diverse group.
• Any single-celled eukaryote that is not a plant,
  animal, or fungi can be called a protist.
• Protists did not descend from a single common
  ancestor.
• For many years, biologists recognized four major
  groups of protists
• flagellates,
• amoebas,
• algae
• parasitic protists.

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KINGDOMS OF DOMAIN EUKARYA
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KINGDOMS OF DOMAIN EUKARYA
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