Cladistics - Systematics

Cladistics and how to make a cladogram.

1. Systematics, then, is no less than understanding the history of all life. -Diana Lipscomb, 1998

2. CLADISTICS LIWALUG, MUSLIMA P. MIB1

3. Method that groups organisms that share derived characteristics The value or form of a feature is referred to as a character state Relationships are portrayed in straight line diagrams Phylogenetic Systematics

4. C L D A I t c i s s

5. C L D A I t c i s s

6. C L D A I t c i s s Cladistic Analysis by Willi Hennig (1966) is to determine which character states are primitive and which are derived based on common ancestry

7. C L D A I t c i s s Principles Parsimony – states that any hypothesis that requires fewer assumptions is a more defendable hypothesis Occam’s Razor - one should not make more assumptions than the minimum needed to explain anything

8. A B

9. C L D A I t c i s s Cladogram is an evolutionary tree which shows evolutionary relationships by showing points at which lineages diverged from common ancestral forms is constructed such that the number of changes from one character state to the next is minimized is interpreted as that which requires the fewest evolutionary changes in the taxa involved

10. Clade a group of two or more taxa that includes both their common ancestor and all their descendants C L D A I t c i s s

11. FOUR LIMBS WITH DIGITS Tetrapoda clade 1 Amniota clade 2 Reptilia clade 3 Diapsida clade 4 Archosauria clade 5 EMBRYO PROTECTED BY AMNIOTIC FLUID OPENING IN THE SIDE OF THE SKULL SKULL OPENINGS IN FRONT OF THE EYE & IN THE JAW FEATHERS & TOOTHLESS BEAKS. SKULL OPENINGS BEHIND THE EYE DERIVED CHARACTER

12. Node - a branch points based on homologous, shared derived traits Root - the common ancestor of all taxa Branch - defines the relationship between the taxa in terms of descent and ancestry Branch length (scaled trees only) - represents the number of changes that have occurred in the branch C L D A I t c i s s

13. C L D A I t c i s s Root Branch Clade Node

14. C L D A I t c i s s Cladistic Methodology more primitive more derived Terminal taxa X Y Z Leopard Turtle Salamander Tuna

15. C L D A I t c i s s Outgroup Comparison If the 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 the character can be considered plesiomorphic

16. P P P P P P A A A A A A

17. Characters TAXON Moss Fern Pine Daisy VASCULAR TISSUES SEEDS FLOWERS P A A A A A A P P P P P

18. Moss (a) All of the plant groups shown here except mosses have vascular Pine Daisy Fern Node 1 Common plant ancestor Common ancestor with vascular tissues

19. Moss Pine Daisy Fern Node 1 Common plant ancestor Common ancestor with vascular tissues Node 2 (b) Seeds are a shared character for all plant groups shown here except mosses and ferns.

20. Moss Pine Daisy Fern Node 1 Common plant ancestor Common ancestor with vascular tissues Node 2 Node 3 Common seed- producing ancestor (c) Of the plant groups shown here, only the daisy produces flowers.

21. Cladogram

22. C L D A I t c i s s Phyletic Group of Taxa MONOPHYLETIC GROUP Contains an ancestor and all of its descendants - defined by > 1 shared, derived traits. POLYPHYLETIC GROUP Does not include common ancestor group. Common ancestor is placed elsewhere PARAPHYLETIC GROUP Includes common ancestor but not all of its descendants. Define by what it lacks.

23. C L D A I t c i s s WHY DO CLASSIFICATION SCHEMES CHANGE? New Data Rise of new technologies give new sources of character information New taxa As previously unknown species are discovered, classifications will also need to be revised to reflect their placement