1. What is a synapomorphy?

2. Terms systematics [taxonomy, phylogenetics] phylogeny/phylogenetic tree cladogram tips, branches, nodes homology apomorphy synapomorhy autapomorphy plesiomorphy symplesiomorphy homoplasy convergence reversal of trait systematics [taxonomy, phylogenetics] phylogeny/phylogenetic tree cladogram tips, branches, nodes homology apomorphy synapomorhy autapomorphy plesiomorphy symplesiomorphy homoplasy convergence reversal of trait monophyletic paraphyletic polyphyletic tree polarity outgroup ancestral group sister group character congruence topological congruence maximum parsimony monophyletic paraphyletic polyphyletic tree polarity outgroup ancestral group sister group character congruence topological congruence maximum parsimony People Willi Hennig

3. Principles of Phylogenetics: Tree Thinking Wings No Yes

4. PHYLOGENETIC INFERENCE  Seeks to recover the historical genetic patterns of relationships among organisms

5. PHYLOGENETIC INFERENCE Principles:  Assumes similar features are homologous until shown otherwise

6. correspondence (morphological, molecular, behavioral) inherited through common ancestry HOMOLOGY

7. F&H Fig 2.1 Structural homologies

8. PHYLOGENETIC INFERENCE  Assumes similar features are homologous until shown otherwise Willi Hennig (1950s-1960s) Principles:  Uses shared derived features, not shared ancestral ones (Hennig formalized this)

9. synapomorphy sharedderivedcharacter Homo Australopithecus Large braincases

10. autapomorphy uniquelycharacterderived H. sapiensAustralopithecus High forehead

11. symplesiomorphy characterancestralshared HomoAustralopithecus bipedal

12. synapomorphy sharedderivedcharacter autapomorphy uniquelycharacterderived symplesiomorphy characterancestralshared

13. PHYLOGENETIC INFERENCE  Uses shared derived features, not shared ancestral ones (Hennig formalized this)  Assumes similar features are homologous until shown otherwise  Treats shared derived features (character states) as markers of historical relatedness Principles:

14. PHYLOGENETIC INFERENCE  Uses shared derived features, not shared ancestral ones (Hennig formalized this)  Assumes similar features are homologous until shown otherwise  Treats shared derived features (character states) as markers of historical relatedness  Same basic logic used for comparative morphology or DNA Principles:

15. Tree-speak node tip branch tip

16. BUMBLE BEE external skeleton wings 6 legs hair “cold-blooded” TANAGER internal skeleton wings 2 legs feathers “warm-blooded” TREE FROG internal skeleton no wings 4 legs no hair or feathers “cold-blooded” OPOSSUM Internal skeleton no wings 4 legs hair “warm-blooded” A simple example…..

17. First taking one character at a time…. Skeleton External Internal Character Character State (0) (1)

18. First taking one character at a time…. Skeleton External Internal (0) (1)

19. Wings NoYes But ….

20. bird wings are homologous to front legs of frogs and opossum. and NOT to wings of bee so…

21. Wings No Yes, but convergent

22. But …. Legs 246

23. so… bird wings are homologous to front legs of frogs and opossum. so birds have 4 legs!

24. Legs 46 really….

25. (actually bumble bees can be endothermic temporarily…) metabolism Poikilothermic (“cold-blooded”) Endothermic (“warm-blooded”)

26. Body covering Just skinFeathers Hair But….

27. Hair Is hair of opossum and bee really homologous? We can test whether these groups share common ancestry using other characters….

28. Skeleton ExternalInternal Legs 46 Metabolism Poikilothermic (“cold-blooded”) Endothermic (“warm-blooded”) Body covering Just skinFeathers Hair Character state trees Wings NoYes, but convergent

29. How can we combine the information from different characters to infer an overall phylogeny? Skeleton ExternalInternal Wings NoYes, but convergent Legs 46 Metabolism Poikilothermic (“cold-blooded”) Endothermic (“warm-blooded”) Body covering Just skinFeathers Hair

30. How can we combine the information from different characters to infer an overall phylogeny? If for only a few characters with no conflict, you can do this in your head, but Quantitative methods are now implemented by computer to do this!

31. First, make up a [character x taxon] matrix, converting ancestral states to 0’s and derived to 1’s or 2’s Bumble bee Tree frog Tanager Opossum LegsSkeletonWingsMetabolismCovering 01102 10000 12011 10012

32. How do we know which state of a character is the ancestral one and which is derived? --Fossils may help show earlier appearance! --Outgroup Analysis States found within a group and also in related groups (outgroups) are more likely to be ancestral than those found only within the group

33. Poikilothermy is likely to be ancestral in frog/bird/mammal group States found within a group and also in related groups (outgroups) are more likely to be ancestral than those found only within the group (ingroup) outgroup ingroup poikilothermic endothermic

34. Bumble bee Tree frog Tanager Opossum LegsSkeletonWingsMetabolismCovering 01102 10000 12011 10012

35. These are then “optimized” onto possible phylogenetic trees, and the tree that requires the fewest total changes of character state is chosen as the most likely (basic parsimony analysis) (It is also possible to make decisions among trees based upon the likelihood of alternative changes, rather than simply the evolutionarily “shortest” tree (we’ll see this with molecular data)

36. Using only the shared derived states….! skeleton 1 wings 1 2 legs 1 metabolism 1 2 covering 2 1 Bumble bee Tree frog Tanager Opossum 01 10 2 10 00 0 12 01 1 10 01 2 SkelWingLegMetabCov

37. How do we resolve differences in relationships implied by different characters (character state conflict)? Metabolism Poikilothermic (“cold-blooded”) Endothermic (“warm-blooded”) Body covering Just skin Feathers Hair

38. skeleton 1 wings 1 2 legs 1 metabolism 1 2 covering 2 This tree requires 8 steps, including an extra step (homoplasy) due to convergence in covering character 1

39. Cover Bumble bee Tree frog Tanager Opossum 01 10 2 10 00 0 12 01 1 10 01 2 SkelWingLegMetab Using only the shared derived states….! 1 1 2 1 1 2 1 2 8 steps steps How many steps or evolutionary changes result from mapping the different character states onto these two other tree topologies? Using the principle of maximum parsimony, which tree would be selected as the more likely ? (See next pg.)