Lesson 4 - Phylogeny

• What is a phylogram?

  A scaled phylogenetic tree
• What do the branch lengths in a phylogram represent?

  The amount of evolutionary divergence
• What is a derived characteristic unique to a lineage called?

  Apomorphy
• What does plesiomorphy refer to?


  An ancestral character shared by a clade
• What is a synapomorphy?


  A derived trait shared by taxa
• What does homoplasy describe?

  A feature gained or lost independently
• What are the characteristics of a Venn diagram in taxonomy?

  • Circular regions represent groups
  • Overlapping regions share common members
  • Non-overlapping regions do not share members
• How do bat and bird wings differ in structure?

  Bat wings have skin flaps; bird wings have feathers
• What are the differences between monophyletic, polyphyletic, and paraphyletic trees?

  • Monophyletic: common ancestor and all descendants
  • Polyphyletic: do not share a common ancestor
  • Paraphyletic: common ancestor but not all descendants
• What does a monophyletic group include?


  Common ancestor and its descendants
• What characterizes a polyphyletic group?


  It does not share a common ancestor
• What defines a paraphyletic group?


  It has a common ancestor but not all descendants
• How are reptiles and birds classified in relation to each other?

  • Birds are closely related to reptiles
  • Reptiles do not form a clade with birds
  • Birds may be grouped into a different clade
• What is the significance of the term "Sauropsida"?

  It groups reptiles and birds together