Animal Classification, Phylogeny, and Organization

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Animal Classification, Phylogeny, and Organization

• Chapter 7
• Zoology

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What does it mean to be alive?

• Order made of atoms?molecules?cells?tissues?orga
  ns?
• organ systems.
• 2. Evolutionary Adaptations able to change.
• 3. Responsiveness respond to env. stimuli.
• 4. Regulation homeostasis.
• 5. Energy Processing metabolism.
• 6. Growth and Development prescribed patterns
  of growing.
• 7. Reproduction use DNA as genetic information
  for replicating.

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Why Classify Organisms?

• Making sense of the living world.

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History of Taxonomy

• Discussion of grouping started by Greek
  philosopher Aristotle.
• About 384 BC grouped things as Animal, Plant, or
  Mineral.
• Why so simple?
• Where are the bacteria?

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Carolus Linnaeus (Karl von Linné, 1707-1778)

• Divided all living things into 2 groups Plants
  and Animals.
• Again, no bacteria?

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Linnaeus System

• Used a hierarchial system
• KPCOFGS (later Domain was added)
• Latinized descriptive names of organisms
  -Binomial Nomenclature 2 word scientific
  naming system
• First part of binomial genus Always
  capitalized
• Second part specific epithet one species,
  always lower case.
• Latin scientific names are always italicized (if
  word processing) or underlined (if hand written)
• Ex. Homo sapiens, wise man

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History of Taxonomy

• 1942 Ernst Mayr proposed biological species
  concept population or groups of populations
  that may interbreed and produce viable, fertile
  offspring.
• 1969 Robert Whittaker proposed the 5 kingdoms
• Monera (later Eubacteria and Archaebacteria
  )Protista, Plantae, Fungi, Animalia
• Based on molecular evidence (DNA and protein
  sequences) its accepted to have 6 Kingdoms and
  have added 3 Domains

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Binomial Nomenclature Who cares?

• What do you call this?
• Crawdad?
• Crawfish?
• Crayfish?
• I call it a Prairie crayfish-Procambarus
  gracilis (Bundy) ? name of scientist who first
  described and named it.

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Why use Binomial Nomenclature?

• Problems with common names
• Varies from area to area, therefore, no
  commonality.
• Does not specify a particular species.
• Each animal has an unique binomial name.
• Required for all animals by International Code of
  Zoological Nomenclature.

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Classification is like an Address!
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6 Kingdoms now Outdated!
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Domain Archaea

• Prokaryotic microbes
• Live in extreme environments high temps, salts,
  acids
• Anaerobic
• Most primitive

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Domain Eubacteria

• Prokaryotic microbes
• Live in most environments
• Anaerobic or aerobic

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Domain Eukarya

• Eukaryotic
• Mainly aerobic but can be anaerobic
• Includes all other kingdoms (Protista, Plant,
  Fungi, Animal)

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Fields of Study in Animal Diversity

• Phylogeny
• The evolutionary history of a species or group of
  related species.
• Systematics
• Determining evolutionary relationships of
  organisms (the study of phylogeny).
• Taxonomy
• Assigning organisms to different categories based
  on their evolutionary relationships.
• Nomenclature
• The science of naming organisms

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• Though sedimentary fossils are the most common
• Paleontologists study a wide variety of fossils

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Morphological and Molecular Homologies

• In addition to fossil organisms
• Phylogenetic history can be inferred from certain
  morphological and molecular similarities among
  living organisms .
• In general, organisms that share very similar
  morphologies or similar DNA sequences
• Are likely to be more closely related than
  organisms with vastly different structures or
  sequences.
• Not always true! Analogy vs. Homology

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Homology

• Homologous Structures structures in different
  species that are similar because of common
  ancestry.

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Analogy

• Analogous Structures similarity in structures
  due to adaptations from similar evolutionary
  pressures (convergent evolution) and not a common
  ancestor.

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• Convergent evolution occurs when similar
  environmental pressures and natural selection
• Produce similar (analogous) adaptations in
  organisms from different evolutionary lineages

Australian Mole marsupial mammal
North American Mole placental mammal
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Convergent Evolution in Snakes
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Sorting Homology from Analogy

• A potential misconception in constructing a
  phylogeny
• Is similarity due to convergent evolution, called
  analogy, rather than shared ancestry

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Linking Classification and Phylogeny

• Systematists depict evolutionary relationships
• In branching phylogenetic trees

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• Each branch point
• Represents the divergence of two species

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• Deeper branch points
• Represent progressively greater amounts of
  divergence

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• Phylogenetic systematics informs the construction
  of phylogenetic trees based on shared
  characteristics
• Cladogram - a depiction of patterns of shared
  characteristics among taxa a graphic organizer
  based on measurable traits and not evolutionary
  relationships.
• Clade - a group of species that includes an
  ancestral species and all its descendants.
• Clades may be nested within larger clades, but
  not all groupings or organisms qualify as clades
• Clades are not phylogenetic trees a trait may be
  analogous. Ex. Bipedalism (humans, kangaroos,
  ostrich).
• Cladistics - Is the study of resemblances among
  clades

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Cladogram for Transportation

• Wheels are the most ancestral (oldest).
• Wings are the most derived (newest).
• This is an example of hierarchical nesting

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• A valid clade is monophyletic
• Signifying that it consists of the ancestor
  species and all its descendants only grouping
  used as legitimate clade.

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• A paraphyletic clade
• Is a grouping that consists of an ancestral
  species and some, but not all, of the descendants

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• A polyphyletic grouping
• Includes numerous types of organisms that lack a
  common ancestor

Grouping 3
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Construct a Cladogram for Us!
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Gorilla

• Four limbs
• Fur
• No tail

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Tiger

• Four limbs
• Fur
• Tail

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Lizard

• Four limbs
• Tail

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Fish

• Tail

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Chimpanzee

• Four limbs
• Fur
• No tail

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Clade With 4 Limbs
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Clade With Fur
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Clade With No Tail
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Characteristics (Traits) for Constructing this
Cladogram

• Tail is the most ancestral
• Four limbs is the oldest derived trait
• Fur is a later derived trait
• Loss of tail is the most recent derived trait

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One Possible Cladogram
Gorilla
Chimpanzee
Tiger
Lizard
Fish
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Wheres the Tail?

• How do we know the gorilla and chimpanzee have
  lost their tail?
• Sometimes cladists must compare embryological
  development and internal anatomy to determine
  relatedness.
• May not be exactly the same structures.

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Coccyx- Primate Vestigial Tails
Human Pelvic Girdle
Gorilla Pelvic Girdle
Vestigial Structure - historical remnants of a
structure that has little or no use in a modern
organism but had a function in ancestors.
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Some Cladistic Terms

• Symplesiomorphies or Shared Primitive Characters
  - homologous structures that predates the
  branching of a particular clade from other
  members of that clade.
• Is shared beyond the taxon we are trying to
  define.
• Not helpful in describing relationships. Why?
• Synapomorphies or Shared Derived Characters - is
  an evolutionary novelty unique to a particular
  clade.
• Is helpful in describing relationships.

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Outgroups

• Systematists use a method called outgroup
  comparison
• To differentiate between shared derived and
  shared primitive characteristics

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• As a basis of comparison we need to designate an
  outgroup
• which is a species or group of species that is
  closely related to the ingroup, the various
  species we are studying.
• Outgroup Comparison
• Is based on the assumption that homologies
  present in both the outgroup and ingroup must be
  primitive characters that predate the divergence
  of both groups from a common ancestor

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A Vertebrate Cladogram