Evo Bio CH 3

• Phylogeny


  the evolutionary history of a particular group
• Phylogeny

  • Genealogical relationships among organisms
  • Based on species sharing a common ancestor
  • Relationships can be portrayed as branching diagrams

  A) common ancestor

  B) common ancestor

  
• Linnaeus was the father of taxonomy
• taxonomic categories

  1. domian
  2. kingdom
  3. phylum
  4. class
  5. order
  6. family
  7. genus
  8. species
• Taxonomy vs. Systematics

  • Taxonomy – naming of organisms
  • Systematics – placing organisms within a classification, includes taxonomy
• phylogeny defines classification

  define the groups

  A) monophyletic

  B) Paraphyletic

  C) Polyphyletic

  
• according to the diagram, are fish monophyletic?

  no, fish are not monophyletic due to shared evolutionary history

  A) common ancestor

  
• according to the diagrams, are these phylogenies different?

  Yes. comparing placental mammals to others

  the correct diagram is A

  
• A couple of warnings about phylogenetic trees

  1. We do not have direct knowledge of evolutionary history
  2. Phylogenies are inferred indirectly from data
• sinistral - aperture faces left


  dextral - aperture faces right
• introns - non coding 


  exons - coding
• Ancestral may be a modern trait, but it is the same as the common ancestor


  Derived traits are modifications different from the ancestral form... not found in common ancestor
• plesiomorphic


  An evolutionary trait that is homologous within a particular group of organisms but is not unique to members of that group and therefore cannot be used as a diagnostic or defining character for the group, a primitive or ancestral character. ex: presence of legs in reptiles
• apomorphic 


  a novel evolutionary character unique to a particular clade and all its descendants, a derived or specialized character. ex: absence of legs in snakes
• autapomorphy


  a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to the focal taxon (which may be a species, family or in general any clade). a very new derived character.
• synapomorphy


  a characteristic present in an ancestral species and shared exclusively (in more or less modified form) by its evolutionary descendants.

  
• Synapomorphies are nested

  black- reptiles, red- mammals

  
• 0 - no character , 1 - has the character

  
• Homoplasious Characters


  • Convergence

  • Similar characters that evolved more than once
• Homologous Characters


  Similar characters in a lineage 
• Tree Roots

  Direction of  rooted tree implies passage of time

  
• Unrooted Trees


  •Do not imply passage of time

  •Relationships are shown but sequence of ancestry could be different

  
• Branch Lengths

  • Some trees are drawn with different length branches

  • Size of branches implies we can infer something about amount of evolutionary change

  • Phylogram = cladogram with branch lengths

  
• Chronogram includes timing
• phylogenesis: the evolutionary development and diversification of a species or group of organisms, or of a particular feature of an organism.
• if a light-colored species of pocket mouse begins living on the dark-colored rocks of an ancient lava flow and evolves a darker coat color, we would consider dark fur to be the derived form of the trait and light fur to be the ancestral form.