Photosynthesis

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Outline

• Taxonomy
• Binomial System
• Species Identification
• Classification Categories
• Phylogenetic Trees
• Systematics
• Taxonomy (naming of organisms)
• Classification (placing species in the proper
  categories)
• Systematics Today
• Cladistic Systematics
• Phenetic Systematics
• Classification Systems
• The Five Kingdom System
• The Three Domain Ssytem

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Taxonomy

• Branch of biology concerned with identifying,
  naming, and classifying organisms
• Began with the ancient Greeks and Romans
• Aristotle classified organisms into groups such
  as horses, birds, and oaks
• John Ray (16271705)
• Believed that each organism should have a set
  name
• Otherwise, mencannot see and record accurately.

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Classifying Organisms
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TaxonomyBinomial System

• Mid-eighteenth century, Linnaeus developed the
  binomial system of nomenclature
• First word is genus name
• Second word is specific epithet
• Refers to one species (of potentially many)
  within its genus
• A species is referred to by the full binomial
  name (Genus species)
• Genus name can be used alone to refer to a group
  of related species

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Carolus Linnaeus
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TaxonomyDistinguishing Species

• Distinguishing species on the basis of structure
  can be difficult
• Members of the same species can vary in structure
• Attempts to demonstrate reproductive isolation is
  problematic because
• Some species hybridize, and
• Reproductive isolation is difficult to observe

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Members of a Species
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Hybridization between species
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Classification Categories

• Modern taxonomists use the following
  classification
• Species
• Genus one or more species
• Family one or more genera
• Order one or more families
• Class one or more orders
• Phylum one or more classes
• Kingdom one or more phyla
• Domain one or more kingdoms

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Hierarchy of Taxa forParthenocissus quinquefolia
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Classification Categories

• The higher the category, the more inclusive
• Organisms in the same domain have general
  characteristics in common
• In most cases, classification categories can be
  subdivided into additional categories
• Superorder
• Order
• Suborder
• Infraorder

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Phylogenetic Trees

• Systematics - the diversity of organisms at all
  levels
• One goal of systematics is to determine phylogeny
  (evolutionary history) of a group
• Phylogeny often represented as a phylogenetic
  tree
• A diagram indicating lines of descent
• Each branching point
• Is a divergence from a common ancestor
• Represents an organism that gives rise to two new
  groups

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Classification and Phylogeny
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Phylogenetic Trees

• Classification lists the unique characters of
  each taxon and is intended to reflect phylogeny
• Primitive characters
• Present in all members of a group, and
• Present in the common ancestor
• Derived characters
• Present in some members of a group, but
• Absent in the common ancestor

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Tracing Phylogeny

• Fossil Record
• Fossil record is incomplete
• It is often difficult to determine the phylogeny
  of a fossil
• Homology
• Refers to features that stem from a common
  ancestor
• Homologous structures are related to each other
  through common descent
• Analogy
• Similarity due to convergence

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Ancestral Angiosperm
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Tracing Phylogeny

• Convergent Evolution
• The acquisition of a feature in distantly related
  lines of descent
• The feature is not present in a common ancestor
• Parallel Evolution
• The acquisition of a feature in two or more
  related lineages
• The feature is not present in a common ancestor

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Convergent Evolution
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Molecular Data

• Protein Comparisons
• Immunological techniques
• Degree of cross reaction used to judge
  relationship
• Amino acid sequencing
• Similar sequence in same protein indicates close
  relationship
• RNA and DNA Comparisons
• Systematics assumes
• Two species with similar base-pair sequences are
  assumed to be closely related
• Two species with differing base-pair sequences
  are assumed to be only distantly related
• Molecular Clocks
• Use non adaptive nucleotide sequences
• Assumed constant rate of mutation over time

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Ancestry of Giant Pandas
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Molecular Data
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Cladistic Systematics

• Traces evolutionary history of the group under
  study
• Uses shared derived characters to
• Classify organisms, and
• Arrange taxa into a cladogram
• A cladogram is a special type of phylogenetic
  tree
• A clade is an evolutionary branch that includes
• A common ancestor, together with
• All its descendent species

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Constructing a Cladogram
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Parsimony

• Cladists are always guided by the principle of
  parsimony
• The arrangement requiring the fewest assumptions
  is preferred
• This would
• Leave the fewest number of shared derived
  characters unexplained
• Minimize the number of assumed evolutionary
  changes
• The reliability of a cladogram is dependent on
  the knowledge and skill of the investigator

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Alternate, Simplified Cladograms
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Cladistic Versus Traditional View ofReptilian
Phylogeny
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Phenetic Systematics

• Assumes it will never be possible to construct a
  truly phylogenetic classification system
• Species are classified according to the total
  number of shared similarities
• Disregards assumed phylogenetic considerations
• Ignores issues of convergent or parallel evolution

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Traditional Systematics

• Mainly uses anatomical data
• Classify organisms using assumed phylogeny with
  emphasis on phenotype
• Stress both common ancestry and degree of
  structural difference among divergent groups
• Construct phylogenetic trees by applying
  evolutionary principles to categories
• Not strict in making sure all taxa are
  monophyletic

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Classification Systems

• Until the middle of the twentieth century,
  biologists recognized only two kingdoms
• Plantae (plants)
• Animalia (animals)
• Protista (protists) were added as third kingdom
  in the 1880s
• Whittaker expanded to five kingdoms in 1969 by
  adding Fungi and Monera

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Three-Domain System

• The Bacteria and Archaea are so different they
  have been assigned to separate domains
• Similar in that both are asexually reproducing
  unicellular prokaryotes
• Distinguishable by
• Difference in rRNA base sequences
• Plasma membrane chemistry
• Cell wall chemistry

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Three-Domain System

• Domain Eukarya
• Unicellular and multicellular organisms
• Cells with a membrane-bounded nucleus
• Sexual reproduction common
• Contains four kingdoms
• Kingdom Protista
• Kingdom Fungi
• Kingdom Plantae
• Kingdom Animalia

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The Three-DomainSystem of Classification
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The Three Domains of Life
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Review

• Taxonomy
• Binomial System
• Species Identification
• Classification Categories
• Phylogenetic Trees
• Systematics
• Taxonomy (naming of organisms)
• Classification (placing species in the proper
  categories)
• Systematics Today
• Cladistic Systematics
• Phenetic Systematics
• Classification Systems
• The Five Kingdom System
• The Three Domain System

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