Unit 5: The Diversity of Life
Chapter 22: Systematics (Classification)
Systematics
 The scientific study of the diversity of
organisms and their evolutionary relationships
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Taxonomy – the science of naming,
describing, and classifying organisms
Classification – arranging organisms into
groups based on their similarities, which reflect
historical relationships among lineages
Binomial Nomenclature
 Carolus Linnaeus
simplified the
complicated, older
system of classification
 Binomial System of
Nomenclature
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Makes classification an
international science
 Each species assigned a
two-part name
How to Write Scientific Names
1. First part of a scientific name = genus
2. Second part of scientific name = specific epithet
3. Genus name is always capitalized.
4. Specific epithet is not capitalized.
5. Scientific names are typed in italics
6. Scientific names are underlined (separately) if
handwritten
7. Ex. Scientific name for dog
Canis familiaris or Canis familiaris
Taxonomic Levels
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Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
*A taxon is a formal grouping of organisms at a
specific level, such as the genus.
Domains and Kingdoms
 3 Domains:
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Archaea
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Eubacteria
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Kingdom Archaebacteria
Kingdom Eubacteria
Eukarya
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Kingdom Protista
Kingdom Fungi
Kingdom Plantae
Kingdom Animalia
Kingdom Archaebacteria
 Prokaryotes
 Unicellular
 Microscopic
 Peptidoglycan absent in cell walls
 Differ biochemically from eubacteria
 Ecological Role:
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Live in extreme environments:
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Methanogens – sewage, swamps
Halophiles – salty environments
Thermophiles – hot, acidic environments
Kingdom Eubacteria
 Prokaryotes
 Unicellular
 Microscopic
 Cell walls composed of peptidoglycan
 Ecological Role:
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Most are decomposers
Some chemosynthetic
Some photosynthetic
Important in recycling nitrogen
Kingdom Protista
 Eukaryotes
 Mainly unicellular or simple multicellular
 3 informal groups:
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Protozoa
Algae
Slime Molds/Water Molds
 Ecological Role:
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Protozoa - Zooplankton
Algae - Important producers
Important oxygen source
Animal-Like Protists: Protozoans
Plantlike Protists: Unicellular
Algae
Plantlike Protists: Red, Brown, &
Green Algae
Kingdom Fungi
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Eukaryotes
Heterotrophic
Absorb nutrients
Cell walls of chitin
Body composed of threadlike hyphae that form tangled
masses that infiltrate food
 Ecological Role:
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Decomposers
Some parasitic
Used as food
Yeast – bread and alcohol
Drugs – antibiotics
Spoilage, Crop loss
Sac Fungi
Club Fungi
Symbiotic Relationships
 Lichens – symbiotic relationship between fungus
and photosynthetic organism
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Pioneer species
Kingdom Plantae
 Eukaryotes
 Multicellular
 Photosynthetic
 Multicellular reproductive organs
 Alternation of generations
 Cell walls of cellulose
 Ecological Role:
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Primary producers
Source of oxygen in atmosphere
Types of Plants
 Bryophytes (mosses)
 Ferns
 Cone-bearing plants
 Flowering plants –
90% of plants
The Animal Kingdom
 Which of these is an animal?
Kingdom Animalia
 Eukaryotes
 Multicellular heterotrophs
 Complex organ systems
 Ability to move
 Specialized nervous tissue
 Ecological Role:
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Consumers
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Herbivores, carnivores, or detritus feeders
Amazing Fact!
 95% of animals are invertebrates
 Only 5% of animals are vertebrates
7 Essential Functions of Animals
1. Feeding
2. Respiration
3. Circulation
4. Excretion
5. Response
6. Movement
7. Reproduction
Phyla of Animals
 Porifera - sponges
 Cnidaria – jellyfish, sea anemone
 Platyhelminthes – flatworms
 Nematoda – roundworms
 Annelida – segmented worms
 Mollusca – mollusks: octopus, snail, clam, oyster
 Arthropoda – scorpions, crab, all insects
 Echinodermata – sea stars, sea urchins
 Chordata – fish, reptiles mammals, amphibians,
birds
Your Assignment
 Research 10 different organisms and record
their classification levels
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Domain  Species Name (genus and specific
epithet)
 9 must be from the different phyla of animals,
the 10th can be from any other kingdom.
 Due tomorrow!
Phylogeny
 Goal of systematics is to determine phylogeny –
evolutionary relationships
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Homology – implies evolution from a common
ancestor
Shared ancestral characters – suggest a distant
common ancestor
Shared derived characters – indicate a more recent
common ancestor
Molecular systematics – compares DNA for
assessing evolutionary relationships
Cladograms
 Diagrams that illustrate phylogeny
 Base of cladogram – common ancestor for all
taxa being analyzed
 Branch point (node) – immediate common
ancestor of the next group
 Example cladograms p.480