Tree thinking in scholarship biology

1. Tree thinking in scholarship biology Rob Cruickshank Department of Ecology Lincoln University

3. “Just as beginning students in geography need to be taught how to read maps, so beginning students in biology should be taught how to read trees and to understand what trees communicate”Robert O’Hara 1997

4. What is a phylogenetic tree?

5. What is a phylogenetic tree?

6. What is a phylogenetic tree? “The most important diagram in biology” Steve Jones 2009 1837

7. What is a phylogenetic tree? 1859

8. Variations on a theme

9. Variations on a theme

10. Variations on a theme

11. Variations on a theme

12. Variations on a theme

13. Variations on a theme

14. These trees are identical

15. Which tree is different? 1

16. Part 1How to read a phylogeny

17. Which of the four phylogenies shown below depicts a different pattern of relationships to the others? 2

18. Which of the four phylogenies shown below depicts a different pattern of relationships to the others? 3

19. Which of the four phylogenies shown below is false given the larger phylogeny above? 4

20. If you were to add a trout to the phylogeny shown above, where would its lineage attach to the rest of the tree? 5

21. Part 2How to infer shared ancestry

22. Which of the five letters in the phylogeny above corresponds to the most recent common ancestor of a mushroom and a sponge? 6

23. Part 3How to interpret relationships

24. According to the phylogeny shown above, which of the following statements is true? A A green alga is more closely related to a red alga than to a moss. B A green alga is more closely related to a moss than to a red alga. C A green alga is equally related to a red alga and a moss. D A green alga is related to a red alga, but is not related to a moss. 7

25. According to the phylogeny shown above, which of the following statements is true? A A crocodile is more closely related to a lizard than to a bird. B A crocodile is more closely related to a bird than to a lizard. C A crocodile is equally related to a lizard and a bird. D A crocodile is related to a lizard, but is not related to a bird. 8

26. According to the phylogeny shown above, which of the following statements is true? A A seal is more closely related to a horse than to a whale. B A seal is more closely related to a whale than to a horse. C A seal is equally related to a horse and a whale. D A seal is related to a whale, but is not related to a horse. 9

27. Part 4How to infer evolutionary change

28. In the phylogeny shown above, assume that the ancestor had a long tail, ear flaps, external testes and fixed claws. Assuming all evolutionary changes are shown, what traits do sea lions have?A Long tail, ear flaps, external testes and fixed claws B Short tail, no ear flaps, external testes and fixed claws C Short tail, no ear flaps, abdominal testes and fixed claws D Short tail, ear flaps, abdominal testes and fixed claws E Long tail, ear flaps, abdominal testes and retractable claws 10

29. In the phylogeny shown above, assume that the ancestor was not a tree and did not have leaves or seeds. Assuming all evolutionary changes are shown, which of the tips is a tree without leaves?A LepidodendronD PsilotumB ClubmossE FernCOak 11

30. Part 5Common mistakesand how to avoid them

31. Living organisms are not primitive “It is absurd to talk of one animal being higher than another” Charles Darwin 1837

32. Living organisms are not primitive

33. Living organisms are not primitive

34. Living organisms are not ancestors Humans are not descended from chimpanzees, rather humans and chimpanzees share a common ancestor that was neither a human nor a chimpanzee

35. Lineages are not basal

36. Lineages are not basal

37. Lineages are not basal

38. Lineages are not basal

39. Lineages are not basal

40. An example

41. Links Tree thinking challenge http://www.tree-thinking.org/publications.html#science310 Downloadable graphic image of the tree of life http://www.zo.utexas.edu/faculty/antisense/downloadfilestol.html