Classification of Organisms

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Classification of Organisms

• Biology- Chapter 18 (508-533)
• Modern Bio Chapter 17 (336-351)
• Biology Concepts and Connections Chap 15
  (304-310)
• Web cd 15c

18.1 Finding Order in Diversity 18.2 Modern
Evolutionary Classification 18.3 Building the
Tree of Life
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Objectives

• Relate biodiversity to biological classification
• Explain why naturalist replaced Aristotle's
  classification system
• Identify the main criterion that Linnaeus used to
  classify organisms
• List the common levels of modern classification
  from general to specific

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Biodiversity

• Biologists have named and classified almost 2
  million species. However, they estimated that the
  total number of species on Earth is much greater.
  Over time, Scientist have created various systems
  of classification to organize their knowledge of
  the tremendous number of species. Each system
  places species into categories bases on
  particular characteristics

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Classifying Organisms

• biodiversity- the variety of organisms considered
  at all levels from populations to ecosystems
• Continues to grow everyday ? not complete
• Erwin cataloging insects, over 1000 beetles, 30
  million species of insects ww

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Taxonomy

• sciences of describing , naming, and classifying
  organisms
• Taxon or taxa- group with in a taxonomic system
• Aristotle, Greek philosopher, classified
  organisms into only 2 taxa
• 1. animals-land, air, or water,
• 2. Plant- based on stems
• ?As it progresses they realized it was not
  working well

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Linnaean System

• Carolus Linnaeus, Swedish naturalist (1707-1778)
• Developed a system of grouping organisms into
  hierarchical categories according to their form
  and structure
• Simple to complex, 7 categories
• Domain, Kingdom, Phylum, Class, Order, Family,
  Genus, Species
• Did King Philip Come Over For Grape Soda
• Can you do your own?

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Levels of Classification pg1079

1. Domains- prokaryotes or eukaryotes- Eukarya
2. Kingdom- animals or plants- Animalia
3. Phyla (animals) or divisions (plants) Chordata
4. Classes-Mammalia
5. Orders- Carnivora
6. Family- Felidae
7. Genus- Felis
8. Species (Felis catus, domestic cat)

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Binomial Nomenclature

• Linnaeus gave organisms a species name or a
  scientific name that contained 2 parts
• Linnaeus grouped species according to anatomical
  similarities and differences.
• 2 Parts
• 1. genus Homo
• 2. species identifier sapiens
• Species name is written in italics and the genus
  name capitalized, tend to come from Latin roots

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Binomial Nomenclature

• The polar bear, for example, is called Ursus
  maritimus.
• The first part of the nameUrsusis the genus to
  which the organism belongs. A genus is a group of
  similar species. The genus Ursus contains five
  other species of bears, including Ursus arctos,
  the brown bear or grizzly bear.
• The second part of a scientific namemaritimus
  for polar bearsis unique to each species and is
  often a description of the organisms habitat or
  of an important trait. The Latin word maritimus
  refers to the sea polar bears often live on pack
  ice that floats in the sea.
• The scientific name of the red maple is Acer
  rubrum.
• The genus Acer consists of all maple trees.
• The species rubrum describes the red maples
  color.

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Problems With Traditional Classification

• For example, adult barnacles and limpets live
  attached to rocks and have similar-looking
  shells.
• Adult crabs dont look anything like barnacles
  and limpets.
• Based on these features, one would likely
  classify limpets and barnacles together and crabs
  in a different group. However, that would be
  wrong.
• Modern classification schemes look beyond
  overall similarities and differences and group
  organisms based on evolutionary relationships.

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systematic

• More than 200 years ago, Linnaeus grouped
  organisms according to similarities that he could
  readily see. Modern biologists consider not only
  visible similarities but also similarities in
  embryos, chromosomes, proteins, and DNA. In
  systematic, the goal is to classify organisms in
  terms of their natural relationships.

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objectives

• Identify the kinds of evidence that modern
  biologists use in classifying organisms
• Explain what information a phylogenetic diagram
  displays
• State the criteria used in cladistic analysis
• Describe how a cladogram is made
• Explain cladistic taxonomy, and identify one
  conclusion that is in conflict with classical
  taxonomy

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Evolutionary Classification

• What is the goal of evolutionary classification?
• The goal of phylogenetic systematics, or
  evolutionary classification, is to group species
  into larger categories that reflect lines of
  evolutionary descent, rather than overall
  similarities and differences.
• The concept of descent with modification led to
  phylogenythe study of how living and extinct
  organisms are related to one another.
• Advances in phylogeny, in turn, led to
  phylogenetic systematics, or evolutionary
  classification. Phylogenetic systematics groups
  species into larger categories that reflect lines
  of evolutionary descent, rather than overall
  similarities and differences.

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Phylogenetics

• The analysis of the evolutionary or ancestral
  relationships among taxa
• Use phylogenetic diagram or tree
• They can change due to new discoveries and
  investigations
• Determine if any evidence of shared ancestry

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What is a Cladograms

• A clade is a group of species that includes a
  single common ancestor and all descendants of
  that ancestorliving and extinct.
• A clade must be a monophyletic group. A
  monophyletic group must include all species that
  are descended from a common ancestor, and cannot
  include any species that are not descended from
  that common ancestor.
• A cladogram links groups of organisms by showing
  how evolutionary lines, or lineages, branched off
  from common ancestors.
• Modern evolutionary classification uses a method
  called cladistic analysis to determine how clades
  are related to one another.
• This information is used to link clades together
  into a cladogram, which illustrates how groups of
  organisms are related to one another by showing
  how evolutionary lines, or lineages, branched off
  from common ancestors.

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cladistic

• System of phylogenetic analysis that uses shared
  and derived characters
• Shared character- is a feature that all members
  of a group have in common, such as hair in
  mammals or feathers in birds
• Derived character- feature that evolved only
  within the group under consideration, feathers
  evolved with in birds
• Clad- group of organisms that includes an
  ancestor plus all of its descendants
• Cladogram- chart developed
• Fig 17.3

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Building Cladograms

• This cladogram represents current hypotheses
  about evolutionary relationships among
  vertebrates.
• Note that in terms of ancestry, amphibians are
  more closely related to mammals than they are to
  ray-finned fish!

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Derived Characters

• Whether or not a character is derived depends on
  the level at which youre grouping organisms.
  Four limbs, for example, is a derived character
  for the clade tetrapoda. Hair is a derived
  character for the clade Mammalia, but four limbs
  is not derived for mammals. If it were, only
  mammals would have four limbs!
• Specialized shearing teeth is a derived character
  for the clade Carnivoraof which both the coyote
  and lion are members. Neither hair nor four limbs
  is a derived character for this clade.
• Retractable claws is a derived character for the
  clade Felidae (the cats). Notice that lions have
  this trait, but coyotes do not.

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Reading Cladograms

• This cladogram shows a simplified phylogeny of
  the cat family.

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Clades and Traditional Taxonomic Groups
Two clades do include the birds clade Aves, (the
birds themselves), and clade Reptilia. Therefore,
according to cladistics, a bird is a reptile!
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New Techniques Suggest New Trees

• The use of DNA characters in cladistic analysis
  has helped to make evolutionary trees more
  accurate.
• For example, traditionally African vultures and
  American vultures were classified together in the
  falcon family.
• Molecular analysis, however, showed that DNA
  from American vultures is more similar to the DNA
  of storks than it is to the DNA of African
  vultures.

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New Techniques Suggest New Trees

• Often, scientists use DNA evidence when
  anatomical traits alone cant provide clear
  answers.
• For example, giant pandas and red pandas share
  many characteristics with both bears and
  raccoons.
• DNA analysis revealed that the giant panda
  shares a more recent common ancestor with bears
  than with raccoons. Therefore, the giant panda
  has been placed in a clade with bears.
• Red pandas, however, are in a clade with
  raccoons and other animals like weasels and
  seals.

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THINK ABOUT IT

• The process of identifying and naming all known
  organisms, both living and extinct, is a huge
  first step toward the goal of systematics.
• The real challenge, however, is to group
  everythingfrom bacteria to dinosaurs to blue
  whalesin a way that reflects their evolutionary
  relationships.
• Over the years, new information and new ways of
  studying organisms have produced major changes in
  Linnaeuss original scheme for organizing living
  things.

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Modern Classification

• Biologist continue to develop taxomies to
  organize lifes enormous diversity. They
  regularly revise the many branches of the tree
  of life to reflect current hypotheses of the
  evolutionary relationships between groups. They
  have revised the larges and most fundamental
  categories of the Linnean-inspired classification
  system- domains and kingdoms.

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objectives

• Describe the evidence that prompted the invention
  of the three-domain system of classification
• List the characteristics that distinguish between
  the domains Bacteria, Archaea, Eukarya
• Describe the 6-kingdom system of classification
• Identify problematic taxa in the 6-kingdome
  system
• Explain why taxonomic systems continue to change.

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Changing Ideas About Kingdoms

• During Linnaeuss time, living things were
  classified as either animals or as plants.
• Animals were organisms that moved from place to
  place and used food for energy.
• Plants were green organisms that generally did
  not move and got their energy from the sun.
• As biologists learned more about the natural
  world, they realized that Linnaeuss two
  kingdomsAnimalia and Plantaedid not reflect the
  full diversity of life.

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Changing Ideas About Kingdoms

• Classification systems have changed dramatically
  since Linnaeuss time, and hypotheses about
  relationships among organisms are still changing
  today as new data are gathered.

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• Domains Bacteria, Archaea, Eukarya
• Kingdoms
• a. Eubacteria
• b. Archaebacteria
• c. Protista
• d. Fungi
• e. Plantae
• f. Animalia

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The Tree of All Life
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Domain Bacteria

• Members of the domain Bacteria are unicellular
  and prokaryotic. This domain corresponds to the
  kingdom Eubacteria.
• Their cells have thick, rigid walls that
  surround a cell membrane and contain a substance
  known as peptidoglycan.
• These bacteria are ecologically diverse, ranging
  from free-living soil organisms to deadly
  parasites. Some photosynthesize, while others do
  not. Some need oxygen to survive, while others
  are killed by oxygen.

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Domain Archaea

• The domain Archaea corresponds to the kingdom
  Archaebacteria.
• Members of the domain Archaea are unicellular
  and prokaryotic, and they live in some extreme
  environmentsin volcanic hot springs, brine
  pools, and black organic mud totally devoid of
  oxygen. Many of these bacteria can survive only
  in the absence of oxygen.
• Their cell walls lack peptidoglycan, and their
  cell membranes contain unusual lipids that are
  not found in any other organism.

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Domain Eukarya

• The domain Eukarya consists of all organisms
  that have a nucleus. It comprises the four
  remaining kingdoms of the six-kingdom system
  Protista, Fungi, Plantae, and Animalia.

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The Protists Unicellular Eukaryotes

• The kingdom Protista has long been viewed by
  biologists as a catchall group of eukaryotes
  that could not be classified as fungi, plants, or
  animals.
• Recent molecular studies and cladistic analyses
  have shown that the eukaryotes formerly known as
  Protista do not form a single clade. Current
  cladistic analysis divides these organisms into
  at least five clades.
• Since these organisms cannot be properly placed
  into a single taxon, we refer to them as
  protists.

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The Protists Unicellular Eukaryotes

• Most protists are unicellular, but one group,
  the brown algae, is multicellular.
• Some protists are photosynthetic, while others
  are heterotrophic.
• Some display characters that resemble those of
  fungi, plants, or animals.

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Fungi

• Members of the kingdom Fungi are heterotrophs
  with cell walls containing chitin.
• Most fungi feed on dead or decaying organic
  matter. They secrete digestive enzymes into their
  food source, which break the food down into
  smaller molecules. The fungi then absorb these
  smaller molecules into their bodies.
• Mushrooms and other recognizable fungi are
  multicellular, like the ghost fungus shown. Some
  fungiyeasts, for exampleare unicellular.

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Plantae

• Members of the kingdom Plantae are
  multicellular, have cell walls that contain
  cellulose, and are autotrophic.
• Autotrophic plants are able to carry on
  photosynthesis using chlorophyll.
• Plants are nonmotilethey cannot move from place
  to place.
• The entire plant kingdom is the sister group to
  the red algae, which are protists. The plant
  kingdom, therefore, includes the green algae
  along with mosses, ferns, cone-bearing plants,
  and flowering plants.

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Animalia

• Members of the kingdom Animalia are
  multicellular and heterotrophic.
• Animal cells do not have cell walls.
• Most animals can move about, at least for some
  part of their life cycle.
• There is incredible diversity within the animal
  kingdom, and many species of animals exist in
  nearly every part of the planet.