Week 3

• Cladogram


  The graphical representation of the hypothetical relationship (phylogenetic relationship) between different groups of organisms
• Cladogram


  Used in the phylogenetic analysis of organisms to determine the evolutionary relationship between them
• Cladograms are the assumptions for the preparation of phylogenetic trees
• Cladogram


  A phylogenetic tree that shows relationship of taxa based on shared derived characters
• Cladogram


  Derived from Greek words clados and gramma
• Clados


  Means branch
• Gramma


  Means characters
• Parts of a cladogram

  • Root
  • Node
  • Clade/Ingroup
  • Taxon/Outgroup
  • Branch
  • Trait, Feature, or Character
• Root


  The initial common ancestors of all the organisms in a cladogram
• Root


  The starting point for any given cladogram
• Root


  Might also indicate that it comes from some other larger clades
• Node


  Each of this one is a hypothetical ancestor that gives rise to two or more daughter taxa
• Node


  Indicates the bifurcating branch point of divergence in all cladograms
• Node


  Exists in each point where a group of organisms divides or separate into further different groups
• Clade/Ingroup


  Groups of organisms or genes that include the most recent common ancestor of all of its members and all of the descendants of that most recent common ancestor
• Clade/Ingroup


  Is made up of an ancestor and all its descendants
• Clade/Ingroup


  Includes a particular node and all of its connected branches
• Taxon/Outgroup


  The most distantly related group of animals that is not necessarily a clade
• Taxon/Outgroup


  Functions as a point of reference or comparison for the rest of the cladogram
• Branch


  A line that connects all the other parts of the cladogram
• Branch Length


  In some cases, this represents the extent of divergence or the extent of the relationship among different taxa
• Trait, Feature or Character

  Attributes of an organism that are expressed by genes and/or influenced by the environment
• Traits


  Include physical attributes of an organism such as hair color, leaf shape, size etc., and behavioral characteristics such as bird nesting
• Cladograms can be generated based on

  • Morphological/structural characteristics
  • Molecular evidence like DNA, RNA or protein sequencing
• Three steps to build a cladogram

  1. The Table

  2. The Venn Diagram

  3. The Cladogram
• Phylogenetic tree


  The evolutionary relationships among organisms