Classification of Living Things

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Classification of Living Things
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Non-Science Example of Classification

• The item in this picture is
• Automobile
• Truck, Car, or SUV? Car
• Made by? Ford
• Type of Ford car? Mustang
• -Was made in what year? 2002
• -Is it Convertible? No
• -Color? Silver

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Classification Goes from General to Specific

• Automobile Biggest
• Car
• Ford
• Mustang
• 2002
• -Non Convertible
• -Silver - Specific

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Classification

• Classify to group things together based on
  similarities
• Why Classify?
• To make organisms easier to identify
• To make organisms easier to compare
• How do we classify?
• Compare Traits features or characteristics of
  an organisms
• The Science of Classification is called Taxonomy

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Shoe Classification

• Everyone take off one shoe
• Put it in the front of the room on the front desk
• As a group, lets classify the shoes
• Use the characteristics of the shoes to classify
  them into categories
• Remember to start in general and get more
  specific
• The Categories we come up with will be written on
  the board

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Challenges of Classification

• 1. Many different kinds of living things
• Today we have identified and named 1.5 million
  species
• Millions more are believed to be unclassified
• Organisms scattered all over the world, some in
  harsh, difficult to reach environments
• 2. Classifications are made by people
• Opinions may differ from scientist to scientist

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Tools Used to Classify Organisms

• 1. Comparative Morphology
• Compares Physical Structures, Traits
• 2. Evolutionary Relationships
• Related Organisms with common ancestors, Derived
  Characters
• 3. DNA/RNA comparison

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Timeline of Classification

• 1. 384 322 B.C. Aristotle
• 2 Kingdom Broad Classification
• 2. 1735 - Carl Linnaeus
• 2 Kingdom Multi-divisional Classification
• Kingdom, Phylum, Class, Order, Family Genus,
  Species
• 3. Evolutionary Classification (After Darwin)
• Group By lines of Evolutionary Descent
• 4. 5 Kingdom System 1950s
• 5. 6 Kingdom System 1990s
• 6. 3 Domain System 1990s

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Early Classification Aristotle 384-322 B.C.

• 2 Groups Plants and Animals
• Plants Green, Non Mobile
• Further classified based on growth pattern Traits
• Tree, Herb, Shrub
• Animals Not Green, Mobile
• Further classified based on Trait of where
  organism lives
• Water, Air, Land

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How would you classify this using the
Plant/Animal system?
Praying Mantis Green but.. Mobile
Aristotles Grouping of life not specific enough
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Systema Naturae Carl Linnaeus

• Carl Linnaeus (1735) Swedish Botanist
• Reworked Classification system
• Based on Comparative Morphology
• Called his classification Systema Naturae
• Used a hierarchy of categories to classify
• Compared physical traits of Organisms
• Used Comparative Morphology

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Linnaeus Divisions Still Used in Modern
Classification

• 1. Kingdom largest group
• 2. Phylum
• 3. Class
• 4. Order
• 5. Family
• 6. Genus
• 7. Species
• (Most Closely Related)

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Mnemonic Device To help remember categories and
order

• Kingdom - King
• Phylum - Phillip
• Class Came
• Order Over
• Family - For
• Genus - Ginger
• Species - Snaps

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Taxons

• Within each category, a particular group is
  called a Taxon
• Many Taxons for each category
• Ex Mammalia is the Taxon for the Class category
  in Humans
• Ex Homo is the Taxon for the Genus category in
  Humans
• Carnivora is the Taxon for the Order category in
  Lions

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Changes Linnaeus Made to Aristotles System

• Both had 2 Kingdom Systems
• Plantae and Animalia
• Differences
• 1. Plants and Animals were classified using more
  divisions - to account for diversity
• 2. Each division from Kingdom to species is based
  on specific traits
• Ex Vertebrae, Mammary Glands, Diet
• 3. Taxons of each group are descriptive of trait
  being used in forming that group
• Ex Class Mammalia mammary glands are used to
  nurse young

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Linnaeus Introduced Scientific Naming

• Binomial Nomenclature is the 2 word scientific
  name of an organism
• Uses Genus and Species
• Genus is capitalized, not species, all italicized
• In writing the name, cant italicize, so
  underline
• Homo sapien (Genus and species of Human)
• Panthera leo (Genus and species of Lion)
• Used Latin Universal unifying, dead language
• Latin can be understood by all scientists,
  regardless of native language
• Uniform, unlike common name usage
• Ex Cougar, Puma, Panther- all same organism
• name depends upon where you live, but Scientific
  same
• Felis concolor

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Example Classification

• Lion
• 1. Kingdom Animalia (all Animals)
• 2. Phylum Chordata (All vertebrate animals)
• 3. Class Mammalia (All Mammals mammary
  glands)
• 4. Order Carnivora (Meat eaters)
• 5. Family Felidae (includes all Cats)
• 6. Genus Panthera (Includes all roaring
  Cats)
• 7. Species leo (Lions)

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Linnaeus Classification Cont.

• Species shows most closely related orgs. in
  system, but still may show variation
• Ex All common dog breeds are in the same species
  (Canis familiaris)
• Basic Unit of Evolution is the Species
• Speciation is continuous, so Taxonomists have to
  keep naming new species
• Reproductive Barriers try to keep species
  separate
• Does not always work Hybrids
• Donkey and Horse make a sterile Mule

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From Kingdom to Species
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Classification Key

• Also Known as
• Dichotomous Key, Biological Key
• Useful in Identifying Organisms
• Based on Comparison of Morphological Traits
• Use physical features to compare, contrast
• Determine if Organism is in group or not, based
  on Key criteria
• At each level you only have a few contrasting
  characteristics to choose from (if have, if not
  have)
• Ex Tennis shoe, non Tennis shoe
• Body shape plans, Characteristics such as fur
• Refer to your Shark Lab Hand Out

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What are these organisms and how are they
classified?
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Evolutionary Classification

• Groups represent lines of Evolutionary Descent
• Not simply based on simply on Morphology
• Ex Even though they have similar Morphology,
  Dolphins and Sharks are not closely related
• Sharks and Dolphins developed Analogous
  Structures
• due to similar environments
• not common ancestry or common development
• Traits, DNA and RNA analysis used to determine
  relation
• Determines Common Ancestry more basic form of
  life from which new species came

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Cladistics Determines Evolutionary Classification

• Evolutionary Classification compares Homologous
  Structures as well as Genetics
• Homologous Structures Structures with similar
  function and development patterns
• -Divergent Evolution organisms that have a
  common ancestor
• Derived Character new trait which appears in
  more recent (newer) organisms not seen in the
  ancestor organism
• Derived Characters are distinguishing traits
  between organisms in an evolutionary
  classification
• See Overhead of plant adaptations

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Cladogram vs. Comparative (Traditional)
Morphology p.452
Derived Characters
Common Ancestor ?
lt-- Common Ancestor
? ?
Common Ancestor ?
Common Ancestor ?
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Molecular Clock can Determine Relationships and
Derived Characters of Species
New mutations (or characteristics) are added over
evolutionary time the more recent the organism,
the more mutations are seen
Like Derived Character -
We Know how newer species are related to ancestor
orgs due to mutation patterns
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Linnaeus System Evolves from 2 Kingdoms to 6

• As we learned more about different kinds of life,
  there needed to be more Kingdoms
• 1800s Added Kingdom Protista
• Amoeba, Slime Molds
• 1950s Added Fungi and Monera
• Fungi distinguished from Plants
• Prokaryotes (no nucleus) Bacteria given category
• 1970s Split Kingdom Monera into 2 separate
  Kingdoms
• Eubacteria bacteria with peptidoglycan
• Archaebacteria bacteria without peptidoglycan

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6 Kingdom System
Animalia Plantae Fungi Protista Eubacteria Archaea
bacteria
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From 2 Kingdoms to 6p. 458
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Three Domain System

• 1990s
• Domain is larger classification than Kingdom
• Used Technology to compare Ribosomal RNA
  sequences of organisms from bacteria to animals
• Determined how long organisms had been evolving
  independently
• Shows Evolutionary Relationships
• Uses molecular clock to determine how long ago
  orgs were related
• Based on how many sequences are different ( of
  mutations, order of mutations)

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Comparison of Kingdom and Domain Systems P.459

• Three Domains contain 6 different Kingdoms
• Domain Bacteria Eubacteria
• Domain Archaea Archaeabacteria
• Domain Eukarya Protista, Fungi, Plantae,
  Animalia

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4. Three Domain System

• 1. Domain Bacteria
• Corresponds to Eubacteria Kingdom
• Unicellular Prokaryotic Organisms
• No Nucleus
• Ecologically Diverse live everywhere!
• Metabolically Diverse
• Cell Walls contain substance called Peptidoglycan
  special protein and sugar
• Trait used to distinguish between
• Bacteria and Archaea
• Target of many Antibiotics

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Three Domain System

• 2. Domain Archaea Ancient Bacteria
• Corresponds to Kingdom Archaeabacteria
• Unicellular, Prokaryotes
• Metabolically Diverse
• No nucleus
• Live in Extreme environments like those of early
  Earth
• Cell walls without Peptidoglycan
• A trait used to distinguish between Archaea and
  Bacteria Domains

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Three Domain System

• 3. Eukarya
• Contains Kingdoms
• Protista, Fungi, Plantae, Animalia
• Eukaryotic, single or multi-cellular Organisms
• Nucleus
• Most visible life
• Humans are in Domain Eukarya

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Three Domains of LifeP. 460-461