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4 phylogeny-ch26
- 1. Lecture 4: Phylogenyand the Tree of Life Campbell & Reece: Chapter 26
- 2. All life isinterconnected by descent Bacterium Amoeba Pine tree Rattlesnake Humans How to determine the pattern of descent?
- 3. Systematics - fieldof biology dealing with diversity and evolutionary history of life Includes Taxonomy: DINC Description Identification Nomenclature Classification Goal: – Determine Evolutionary History (Phylogeny) of Life
- 4. Description = assignfeatures Character = a feature (e.g., “petal color”) Character states = two or more forms of a character (e.g., “red,” “white”).
- 5. Identification = associatean unknown with a known How? One way: Taxonomic Key, e.g., Tree …………………………………….…………… Species A Leaves simple …….………………………… Species B Leaves pinnate …….………..…..…..…… Species C Herb Flowers red …….…………………………… Species D Flowers white …….…………………..…… Species E
- 6. Nomenclature Naming, accordingto a formal system. Binomial: Species are two names (Linnaeus): E.g., Homo sapiens Homo = genus name sapiens = specific epithet Homo sapiens = species name
- 7. Nomenclature Hierarchical Ranks: Domain Kingdom Phylum Class Order Family Genus Species
- 8. Classification • Placingobjects, e.g., life, into some type of order. • Taxon = a taxonomic group (plural = taxa).
- 9. How to classifylife • Phenetic classification – Based on overall similarity – Those organisms most similar are classified more “closely” together.
- 10. Problem with pheneticclassification: • Can be arbitrary, e.g., classify these:
- 11. Phylogenetic classification •Based on known (inferred) evolutionary history. • Advantage: – Classification reflects pattern of evolution – Classification not ambiguous
- 12. TIME lineage orclade Cladogram or Phylogenetic Tree = representation of the history of life
- 13. TAXA A BC D E F TIME lineage or clade Cladogram or Phylogenetic Tree
- 14. TAXA A BC D E F TIME speciation Cladogram or Phylogenetic Tree
- 15. Ingroup – groupstudied Outgroup – group not part of ingroup, used to “root” tree
- 16. Fig. 26-5 Sister taxa ANCESTRAL LINEAGE Taxon A Branch point (node) Polytomy Common ancestor of taxa A–F Taxon B Taxon C Taxon D Taxon E Taxon F
- 17. Apomorphy (derived trait) = a new, derived feature E.g., for this evolutionary transformation scales -------- feathers (ancestral feature) (derived feature) Presence of feathers is an apomorphy for birds.
- 18. Taxa are groupedby apomorphies Apomorphies are the result of evolution. Taxa sharing apomorphies underwent same evolutionary history should be grouped together.
- 19. Principle of Parsimony That cladogram (tree) having the fewest number of “steps” (evolutionary changes) is the one accepted. Okham’s razor: the simplest explanation, with fewest number of “ad hoc” hypotheses, is accepted.
- 20. Other methods ofphylogeny reconstruction: • Maximum Likelihood or Bayesian analysis – Uses probabilities – Advantage: can use evolutionary models.
- 21. TAXA A BC D E F apomorphy (for Taxon D) apomorphies (for Taxa B C) apomorphy (for Taxa B,C,D,E,F) TIME Cladogram or Phylogenetic Tree
- 22. Sequentially group taxaby shared derived character states (apomorphies) Vertebral column 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Fig. 26-11 TAXA (outgroup) Lamprey Lancelet Salamander Leopard Turtle Tuna Vertebral column (backbone) Hinged jaws Four walking legs Amniotic (shelled) egg CHARACTERS Hair (a) Character table Hair Hinged jaws Four walking legs Amniotic egg (b) Phylogenetic tree Lancelet (outgroup) Lamprey Tuna Salamander Turtle Leopard 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1
- 23. DNA sequence data– most important type of data Fig. 26-8a Deletion Insertion 1 2
- 24. Fig. 26-8b 3 4 DNA sequence data - alignment Each nucleotide position = Character Character states = specific nucleotide
- 25. Homology • Similarityresulting from common ancestry. – E.g., the forelimb bones of a bird, bat, and cat.
- 27. Homoplasy (analogy) •Similarity not due to common ancestry • Reversal – loss of new (apomorphic) feature, resembles ancestral (old) feature. • Convergence (parallelism) – gain of new, similar features independently.
- 28. Convergent evolution: spinesof cacti euphorbs Cactus Euphorb
- 29. Convergent evolution: spinesof cacti euphorbs euphorb spines cactus spines
- 30. Leg-less lizards Snake Both examples of reversal within Tetrapods: loss of a derived feature – forelimbs. Example of convergence relative to one another! Independently evolved. snakes legged leg-less lizards lizards * * *= loss of legs gain of legs (Tetrapods)
- 31. Convergent evolution: wingsof some animals evolved independently
- 32. Fig. 26-7 Convergentevolution: Australian “mole” and N. Am. “mole”
- 33. Orthologous genes SpeciesA Species B Species A Gene duplication and divergence Fig. 26-18 Speciation with divergence of gene (a) Orthologous genes (b) Paralogous genes Ancestral gene Ancestral species Paralogous genes Species A after many generations Orthology – genes homologous Paralogy – genes not homologous Gene Duplication can occur!
- 34. Common ancestry TAXA A B C D E F TIME common ancestor (of taxon A taxa B-F) common ancestor (of taxon D, E, F) Cladogram or Phylogenetic Tree
- 35. Monophyletic Group •a group consisting of: – a common ancestor + – all descendents of that common ancestor
- 36. TAXA A BC D E F monophyletic group TIME common ancestor (of taxon A taxa B-F) common ancestor (of taxon D, E, F) Cladogram or Phylogenetic Tree
- 37. TAXA A BC D E F monophyletic group TIME common ancestor (of taxon A taxa B-F) common ancestor (of taxon D, E, F) Cladogram or Phylogenetic Tree
- 38. TAXA A BC D E F monophyletic group TIME common ancestor (of taxon A taxa B-F) common ancestor (of taxon D, E, F) Cladogram or Phylogenetic Tree
- 39. TAXA A BC D E F monophyletic group TIME common ancestor (of taxon A taxa B-F) common ancestor (of taxon D, E, F) Cladogram or Phylogenetic Tree
- 40. TAXA A BC D E F monophyletic group TIME common ancestor (of taxon A taxa B-F) common ancestor (of taxon D, E, F) Cladogram or Phylogenetic Tree
- 41. TAXA A BC D E F TIME speciation Cladogram or Phylogenetic Tree
- 42. TAXA C BF E D A A B C D E F TIME speciation Cladogram or Phylogenetic Tree Cladograms can be “flipped” at nodes, show same relationships
- 43. Fig. 26-13 Onecan date divergence times with molecular clock and fossils Drosophila Lancelet Zebrafish Frog Chicken Human Mouse CENOZOIC 65.5 Present MESOZOIC 251 Millions of years ago PALEOZOIC 542
- 44. Relationship • =recency of common ancestry i.e., taxa sharing a common ancestor more recent in time are more closely related than those sharing common ancestors more distant in time.
- 45. Example: • Arefish more closely related to sharks or to humans?
- 46. Shark Fish Humans TIME
- 47. Shark Fish Humans TIME common ancestor of Fish and Humans common ancestor of Sharks, Fish, and Humans
- 48. monophyletic group Vertebrata Osteichthyes Shark Fish Humans TIME common ancestor of Fish and Humans common ancestor of Sharks, Fish, and Humans
- 49. Example: • Arecrocodyles more closely related to lizards or to birds?
- 50. Lizards SnakesTurtles Crocodyles Birds
- 51. Reptilia Lizards Snakes Turtles Crocodyles Birds
- 52. Paraphyletic group •Consist of common ancestor but not all descendents • Paraphyletic groups are unnatural, distort evolutionary history, and should not be recognized.
- 53. Reptilia Lizards Snakes Turtles Crocodyles Birds
- 54. “Reptilia” here paraphyletic Reptilia Lizards Snakes Turtles Crocodyles Birds
- 55. Re-defined Reptilia monophyletic Lizards Reptilia Turtles Snakes Crocodyles Birds
- 56. Dinosaurs Lizards Snakes Turtles Crocodyles Birds † † † Reptilia
- 57. Importance of aname: Did humans evolve from apes?
- 58.
- 59. Hominidae Pongidae “GreatApes” Orangatan Gorilla Chimpanzees Humans
- 60. Pongidae or Hominidae Pongidae “Hominidae Great Apes” Orangatan Gorilla Chimpanzees Humans
- 61. Pongidae or Hominidae Hominidae Orangatan Gorilla Chimpanzees Humans
- 62. Pongidae or Hominidae Hominidae Orangatan Gorilla Chimpanzees Humans
- 64. We are human,but we are also apes. • We share unique human features. • We also share features with other apes (and with other animals, plants, fungi, bacteria, etc.). • Humans didn’t evolve from apes, humans are apes.
- 65. Importance of systematics evolution: 1) Foundation of biology - study of biodiversity 2) Basis for classification of life 3) Gives insight into biological processes: speciation processes adaptation to environment 4) Can be aesthetically/intellectually pleasing!
- 66.
- 68. Schistosomiasis: knowledge ofspecies diversity and evolutionary history of primary host can aid in controlling parasite (Schistosoma, a fluke) Phylogeny of Oncomelania snails
- 69. All of lifeis interconnected by descent. TAXA A B C D E F TIME lineage or clade Cladogram or Phylogenetic Tree
- 70. There are no“higher” or “lower” species. TAXA A B C D E F TIME lineage or clade Cladogram or Phylogenetic Tree