Protista (unicellular)

  • Includes Protozoa

Metazoa (multicellular)

  • No “true” tissues: Parazoa (Sponges), Mesozoa
  • True Tissues: Eumetazoa
    • Diploblastic (mostly radially symmetric)
    • Triploblastic (mostly bilaterally symmetric)
      • Acoelomate
      • Pseudocoelomate
      • Coelomate
        • Protostomes
        • Deuterostomes

Cladogram– A cladist presents results in the form of a branching diagram called a “cladogram”. All of the taxa are listed along the top of the cladogram. Each branch underneath the taxa represents common ancestry relationships.

  • The taxa may be living or extinct

Image result for cladogram

“Primate cladogram” by Petter Bøckman under Creative Commons Attribution-Share Alike 3.0 Unported

Pleisomorphic- Primitive condition, ancestral state

Apomorphic- Derived condition, advanced character state

Syanpomorphy- Shared derived character


In Cladistics, all members of a group (clade) should be monophyletic


  • All members of a taxonomic group are derived from a single ancestral form
  • The group should also contain all descendants of that ancestor


  • An organism or a group of organisms that are descended from a common ancestor but it does not include all of the descendant groups


  • A group of organisms that are derived from one or more common ancestor

Evolutionary relationships are inferred from similarities and differences in 

  • morphology
  • development
  • physiology


-A cladogram lacks an absolute time axis, you can’t tell in what year a speciation event occurred

-Branch length is not equivalent to time 

-Parsimony– The simplest explanation, but not always right

  • The smallest number of evolutionary transformations
  • Least complex way of explaining relationships
  • Doesn’t require a lot of losses and then re-gaining characters