BIO 153 - P2

  1. taxa
    (singular, taxon)
    named groups of organisms
  2. phylogeny
    • a diagram of evolutionary history that superficially resembles a cladogram
    • has an absolute time axis
    • instead of at the top, taxa are ordered vertically to indicate when they lived
  3. phylogenetic systematics or
    cladistic analysis
    • Hennig's method for ascertaining genealogies
    • Each dichotomy marks the splitting and disappearance of an ancestral species and the formation of two daughter species
  4. clade
    • monophyletic group
    • (an ancestral species and all of its descendants)
    • all of the taxa that possess a given synapomorphy, but not other taxa
  5. cladogram
    • a branching diagram where all of the taxa under study are listed at the top, with intersecting lines, or branches, beneath them to illustrate their common ancestry relationships
  6. character states
    • a feature that is an observable part or attribute of an organism, in it's different forms or appearances
    • coded by assigning a number: 0, 1...
  7. plesiomorphy
    an "ancestral", "less specialized", or "primitive" character
  8. apomorphy
    a "derived", "specialized", or "advanced" character
  9. outgroup comparison
    a means of determining which character in a transformation series is a plesiomorphy and which is an apomorphy
  10. outgroup
    • the plesiomorphic character state
    • the most closely related taxon to, but not the ancestor of, the set of taxa under study
  11. ingroup
    the taxon under study
  12. synapomorphy
    • shared derived character
    • an apomorphy that occurs in two or more taxa
  13. autapomorphy
    • an apomorphy that occurs in only one taxon
    • demonstrate the uniqueness of taxa, but they don't help identify clades
  14. paraphyletic group
    • consists of an ancestor and some of its descendants
    • an incomplete clade, defined by the absence of at least one character
  15. polyphyletic groups
    • two or more taxa, but not the common ancestor of those taxa
    • defined by at least one similar character that evolved independently (by convergent or parallel evolution)
    • they share some superficial similarity, not because they're closely related to one another
  16. phylogenetic trees
    • are hypotheses about the evolutionary relationships among a group of organisms
    • we develop these hypotheses by observing shared and/or unique traits (characters) in the taxa to be studied
  17. parsimony
    • the shorter tree or the one with the fewest changes
    • this one wins
  18. node
    most recent common ancestor of 2 lineages
  19. homoplasy
    anything that makes your tree more complicated, or adds a step; like convergent evolution or losing a trait
Card Set
BIO 153 - P2