Cladistics, or phylogenetic systematics, organizes organisms based on shared derived characters, distinguishing between primitive (plesiomorphic) and derived (apomorphic) states. An outgroup is used to identify character states, with hypotheses requiring fewer assumptions being preferred. Cladograms serve as a foundation for classification, utilizing data matrices to represent character states and relationships among taxa.

6. The method that groups organisms that share
derived characters is called cladistics or
phylogenetic systematics

9. The first step (Tree polarity)
•Determine which character states are
primitive and which are derived.
• Plesiomorphic character (Prim itive),
• Apomorphic character (Derived)

10. If a taxon that is not a member of the group
of organisms being classified has a character
state that is the same as some of the organisms in
the group, then that character state can be
considered to be plesiomorphic.
The outside taxon is called the outgroup and the
organisms being classified are the ingroup.

12. 1. Any hypothesis that requires fewer assumptions is a more defensible hypothesis.

16. Exercise 1

17. The information in character 1 unites taxa A, B, and C because
they share the apomorphic state.

18. Character 2 - the derived state is found only in taxon B. It is an
autapomorphy of that taxon and provides no information about the
relationships among the taxa

19. Character 3 - the derived state is an autapomorphy for taxon C

20. Character 4 - the derived state is a synapomorphy that unites taxa B
and C

21. Character 5 - the derived state is an autapomorphy for taxon A

22. Construct a cladogram of the
provided data matrix
Five min.

23. Exercise 2

29. One of the most important uses of cladograms is as a basis for
classification. A cladogram may be used to classify taxa
phylogenetically.

65. Create a data matrix

68. Name your taxa

76. Enter character states in the form of (0/1)

79. Save your data matrix

83. Analyze your data

87. Edite your tree

94. Map your characters

102. Save your tree

106. Autapomorphic character
Synapomorphic character
Sister taxa
Homoplasious character