Classification

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• Classification

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The Challenge

• Biologists have identified and named
  approximately 1.5 million species so far.
• They estimate that between 2 and 100 million
  species have yet to be identified.

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Finding Order in Diversity

• 1. Why Classify?
• To study the diversity of life
• To organize and name organisms
• 2. Why give scientific names?
• Common names are misleading

jellyfish
silverfish
star fish
None of these animals are fish!
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Why Scientists Assign Scientific Names to
Organisms

• Some organisms have several common names

• This cat is commonly known as
• Florida panther
• Mountain lion
• Puma
• Cougar

Scientific name Felis concolor Scientific name
means coat of one color
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Origin of Scientific Names

• By the 18th century, scientists realized that
  naming organisms with common names was confusing.
  
• Scientists during this time agreed to use a
  single name for each species.
• They used Latin and Greek languages for
  scientific names.

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Linnaeus The Father of Modern Taxonomy

• 1732 Carolus Linnaeus developed system of
  classification binomial nomenclature
• Two name naming system
• Gave organisms 2 names
• Genus (noun) and species (adjective)
• Rules for naming organisms
• 1. Written is Latin (unchanging)
• 2. Genus capitalized, species lowercase
• 3. Both names are italicized or underlined
• EX Homo sapiens wise / thinking man

Carolus Linnaeus
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• Binomial nomenclature is a two-part scientific
  naming system.

• uses Latin words
• scientific names always written in italics
• two parts are the genus name and species
  descriptor

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Linnaeuss System of Hierarchy
Kingdom
Least specific

• Which of the following contains all of the
  others?
• Family c. Class
• Species d. Order
• Based on their names, you know that the baboons
  Papio annubis and Papio cynocephalus do not
  belong to the same
• Family c. Order
• Genus d. Species

Phylum
Class
Order
Family
Genus
Most specific
Species
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Modern classification is based on evolutionary
relationships.
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Modern Classification

• Linnaeus grouped species into larger taxa, such
  as genus and family, based on visible
  similarities.
• Darwins ideas about descent with modification
  evolved into the study of phylogeny, or
  evolutionary relationships among organisms.

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How do we classify?

• Structural (anatomy and physiology)
• Biochemical (enzymes, proteins, DNA)
• Cytological (cell structure)
• Embryological (development)
• Behavioral (patterns of actions)
• Fossil (common ancestor)

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Modern Classification

• Modern biologists group organisms into categories
  representing lines of evolutionary descent.
• Species within a genus are more closely related
  to each other than to species in another genus.

Genus Felis
Genus Canis
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Similarities in DNA and RNA

• Scientists use similarities and differences in
  DNA to determine classification and evolutionary
  relationships.
• They can sequence or read the information coded
  in DNA to compare organisms.

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Cladistics is classification based on common
ancestry.

• Phylogeny is the evolutionary history for a group
  of species.
• evidence from living species, fossil record, and
  molecular data
• shown with branching tree diagrams

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• Cladistics is a method to make evolutionary trees.

• classification based on common ancestry
• species placed in order that they descended from
  common ancestor

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• A cladogram is an evolutionary tree made using
  cladistics.

• A clade is a group of species that shares a
  common ancestor.

• Each species in a clade shares some traits with
  the ancestor.
• Each species in a clade has traits that have
  changed.

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• Derived characters are traits shared in different
  degrees by clade members.

• basis of arranging species in cladogram
• more closely related species share more derived
  characters
• represented on cladogram as hash marks

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• Nodes represent the most recent common ancestor
  of a clade.

FEATHERS AND TOOTHLESS BEAKS.
SKULL OPENINGS IN FRONT OF THE EYE AND IN THE JAW

• Clades can be identified by snipping a branch
  under a node.

OPENING IN THE SIDE OF THE SKULL
SKULL OPENINGS BEHIND THE EYE
EMBRYO PROTECTED BY AMNIOTIC FLUID
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Molecular evidence reveals species relatedness.

• Molecular data may confirm classification based
  on physical similarities.
• Molecular data may lead scientists to propose a
  new classification.

• DNA is usually given the last word by scientists.

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Molecular clocks provide clues to evolutionary
history.
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Molecular clocks use mutations to estimate
evolutionary time.

• Mutations add up at a constant rate in related
  species.
• This rate is the ticking of the molecular clock.
• As more time passes, there will be more mutations.

The DNA sequences from two descendant species
show mutations that have accumulated (black).
The mutation rate of this sequence equals one
mutation per ten million years.
DNA sequence from a hypothetical ancestor
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• Scientists estimate mutation rates by linking
  molecular data and real time.

• an event known to separate species
• the first appearance of a species in fossil record

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Mitochondrial DNA and ribosomal RNA provide two
types of molecular clocks.

• Different molecules have different mutation
  rates.
• higher rate, better for studying closely related
  species
• lower rate, better for studying distantly related
  species

Ribosomal RNA is used to study distantly related
species

• many conservative regions
• lower mutation rate than most DNA

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• Mitochondrial DNA is used to study closely
  related species.

• mutation rate ten times faster than nuclear DNA
• passed down unshuffled from mother to offspring

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Kingdoms and Domains

• In the 18th century, Linnaeus originally proposed
  two kingdoms Animalia and Plantae.
• By the 1950s, scientists expanded the kingdom
  system to include five kingdoms.

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The Five Kingdom System
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The Six Kingdom System

• In recent years, biologists have recognized that
  the Monera are composed of two distinct groups.
• As a result, the kingdom Monera has now been
  separated into two kingdoms Eubacteria and
  Archaebacteria, resulting in a six-kingdom system
  of classification.

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The Three-Domain System

• Scientists can group modern organisms by
  comparing ribosomal RNA to determine how long
  they have been evolving independently.
• This type of molecular analysis has resulted in a
  new taxonomic categorythe domain.

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The Three Domains

• The three domains, which are larger than the
  kingdoms, are the following
• Eukarya protists, fungi, plants and animals
• Bacteria which corresponds to the kingdom
  Eubacteria.
• Archaea which corresponds to the kingdom
  Archaebacteria.

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The three domains in the tree of life

• Domains are above the kingdom level.
• proposed by Carl Woese based on rRNA studies of
  prokaryotes
• domain model more clearly shows prokaryotic
  diversity

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Classification of Living Things
The three-domain system
Bacteria
Archaea
Eukarya
The six-kingdom system
Eubacteria
Archae- bacteria
Protista
Plantae
Animalia
Fungi
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Hierarchical Ordering of Classification
Coral snake
Abert squirrel
Sea star
Grizzly bear
Black bear
Giant panda
Red fox
KINGDOM Animalia
PHYLUM Chordata
CLASS Mammalia
As we move from the kingdom level to the species
level, more and more members are removed. Each
level is more specific.
ORDER Carnivora
FAMILY Ursidae
GENUS Ursus
SPECIES Ursus arctos
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Kingdom Archaebacteria
Cell Type Prokaryote
Number of Cells Unicellular
Nutrition Autotroph or Heterotroph
Location Extreme Environments Volcanoes, Deep Sea Vents, Yellowstone Hot Springs
Examples Methanogens Thermophiles
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Kingdom Eubacteria
Cell Type Prokaryote
Number of Cells Unicellular
Nutrition Autotroph or Heterotroph
Examples Streptococcus, Escherichia coli (E. coli)
E. coli
Streptococcus
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Kingdom Protista
Cell Type Eukaryote
Number of Cells Most Unicellular, some multicellular
Nutrition Autotroph or Heterotroph
Examples Amoeba, Paramecium, Euglena,
Paramecium
Green algae
The Junk-Drawer Kingdom
Amoeba
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Kingdom Fungi
Cell Type Eukaryote
Number of Cells Most multicelluar, some unicelluar
Nutrition Heterotroph
Example Mushroom, yeast, mildew, mold



Mildew on Leaf
Most Fungi are DECOMPOSERS
Mushroom
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Kingdom Plantae
Ferns seedless vascular
Cell Type Eukaryote
Number of Cells Multicellular
Nutrition Autotroph
Examples Mosses, ferns, conifers, flowering plants
Douglas fir seeds in cones
Sunflowers seeds in flowers
Mosses growing on trees
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Kingdom Animalia
Cell Type Eukaryote
Number of Cells Multicellular
Nutrition Heterotroph
Examples Sponges, worms, insects, fish, mammals
Bumble bee
Jellyfish
Sage grouse
Hydra
Poison dart frog
Sponge
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Dichotomous Key

• Tool used by biologists to identify an unknown
  organism
• Series of paired statements of anatomical
  description that leads to an identification.

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What bird am I ?
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Key for Vertebrate Identification
What am I ???

• 1. a) animal has a spine..go to 2
  
  
• b) animal has no spine..invertebr
  ate
• 2. a) animal has no gills and fins... go to
  3
• b) animal has gills and fins..
  Fish
• 3. a) animal has no scales..........go to 4
• b) animal has scales...reptile
• 4. a) animal has feathers ..bird
• b) animal has no feathers ..go to 5
• 5. a) animal has hair.mammal
• b) animal has no hair..amphibian