4 phylogeny-ch26

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  • 1. Lecture 4: Phylogeny and the Tree of LifeCampbell & Reece:Chapter 26

2. All life is interconnected by descentBacterium Amoeba Pine tree Rattlesnake HumansHow to determine the pattern of descent? 3. Systematics - field of biology dealing withdiversity and evolutionary history of lifeIncludes Taxonomy: DINCDescriptionIdentificationNomenclatureClassificationGoal: Determine Evolutionary History (Phylogeny) of Life 4. Description= assign featuresCharacter = a feature (e.g., petal color)Character states = two or more forms of acharacter (e.g., red, white). 5. Identification= associate an unknown with a knownHow? One way:Taxonomic Key, e.g.,Tree . Species ALeaves simple . Species BLeaves pinnate ....... Species CHerbFlowers red . Species DFlowers white ... Species E 6. NomenclatureNaming, according to a formal system.Binomial: Species are two names (Linnaeus):E.g., Homo sapiensHomo = genus namesapiens = specific epithetHomo sapiens = species name 7. NomenclatureHierarchical Ranks:DomainKingdomPhylumClassOrderFamilyGenusSpecies 8. Classification Placing objects, e.g., life, into some type oforder. Taxon = a taxonomic group (plural = taxa). 9. How to classify life Phenetic classification Based on overall similarity Those organisms most similar are classified moreclosely together. 10. Problem with phenetic classification: Can be arbitrary,e.g., classify these: 11. Phylogenetic classification Based on known (inferred) evolutionaryhistory. Advantage: Classification reflects pattern of evolution Classification not ambiguous 12. TIMElineageor cladeCladogram or Phylogenetic Tree= representation of the history of life 13. TAXAA B C D E FTIMElineageor cladeCladogram or Phylogenetic Tree 14. TAXAA B C D E FTIMEspeciationCladogram or Phylogenetic Tree 15. Ingroup group studiedOutgroup group not part ofingroup, used to root tree 16. Fig. 26-5SistertaxaANCESTRALLINEAGETaxon ABranch point(node)PolytomyCommon ancestor oftaxa AFTaxon BTaxon CTaxon DTaxon ETaxon F 17. Apomorphy (derived trait)= a new, derived featureE.g., for this evolutionary transformationscales --------> feathers(ancestral feature) (derived feature)Presence of feathers is an apomorphyfor birds. 18. Taxa are grouped byapomorphiesApomorphies are the result of evolution.Taxa sharing apomorphiesunderwent same evolutionary historyshould be grouped together. 19. Principle of ParsimonyThat cladogram (tree) having the fewest numberof steps (evolutionary changes) is the oneaccepted.Okhams razor: the simplest explanation, withfewest number of ad hoc hypotheses, isaccepted. 20. Other methods of phylogenyreconstruction: Maximum Likelihood or Bayesian analysis Uses probabilities Advantage: can use evolutionary models. 21. TAXAA B C D E Fapomorphy(for Taxon D)apomorphies(for Taxa B & C)apomorphy(for Taxa B,C,D,E,F)TIMECladogram or Phylogenetic Tree 22. Sequentially group taxa byshared derived character states (apomorphies)Vertebralcolumn1 11111 11 11 1 11 1Fig. 26-11TAXA(outgroup)LampreyLanceletSalamanderLeopardTurtleTunaVertebral column(backbone)Hinged jawsFour walking legsAmniotic (shelled) eggCHARACTERSHair(a) Character tableHairHinged jawsFour walking legsAmniotic egg(b) Phylogenetic treeLancelet(outgroup)LampreyTunaSalamanderTurtleLeopard00 00000 0000 00 0 0 1 23. DNA sequence data most important type of dataFig. 26-8aDeletionInsertion12 24. Fig. 26-8b34DNA sequence data - alignmentEach nucleotide position = CharacterCharacter states = specific nucleotide 25. Homology Similarity resulting from common ancestry. E.g., the forelimb bones of a bird, bat, and cat. 26. 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. 27. Convergent evolution:spines of cacti & euphorbsCactus Euphorb 28. Convergent evolution:spines of cacti & euphorbseuphorb spines cactusspines 29. Leg-less lizards SnakeBoth examples of reversal within Tetrapods:loss of a derived feature forelimbs.Example of convergence relative to one another!Independently evolved.snakesleggedleg-lesslizardslizards* **= loss of legsgain of legs (Tetrapods) 30. Convergent evolution:wings of some animals evolved independently 31. Fig. 26-7Convergent evolution:Australian mole and N. Am. mole 32. Orthologous genesSpecies A Species BSpecies AGene duplication and divergenceFig. 26-18Speciation withdivergence of gene(a) Orthologous genes(b) Paralogous genesAncestral geneAncestral speciesParalogous genesSpecies A after many generationsOrthology geneshomologousParalogy genes nothomologousGene Duplicationcan occur! 33. Common ancestryTAXAA B C D E FTIMEcommon ancestor(of taxon A & taxa B-F)common ancestor(of taxon D, E, & F)Cladogram or Phylogenetic Tree 34. Monophyletic Group a group consisting of: a common ancestor + all descendents of that common ancestor 35. TAXAA B C D E FmonophyleticgroupTIMEcommon ancestor(of taxon A & taxa B-F)common ancestor(of taxon D, E, & F)Cladogram or Phylogenetic Tree 36. TAXAA B C D E FmonophyleticgroupTIMEcommon ancestor(of taxon A & taxa B-F)common ancestor(of taxon D, E, & F)Cladogram or Phylogenetic Tree 37. TAXAA B C D E FmonophyleticgroupTIMEcommon ancestor(of taxon A & taxa B-F)common ancestor(of taxon D, E, & F)Cladogram or Phylogenetic Tree 38. TAXAA B C D E FmonophyleticgroupTIMEcommon ancestor(of taxon A & taxa B-F)common ancestor(of taxon D, E, & F)Cladogram or Phylogenetic Tree 39. TAXAA B C D E FmonophyleticgroupTIMEcommon ancestor(of taxon A & taxa B-F)common ancestor(of taxon D, E, & F)Cladogram or Phylogenetic Tree 40. TAXAA B C D E FTIMEspeciationCladogram or Phylogenetic Tree 41. TAXAC B F E D AA B C D E FTIMEspeciationCladogram or Phylogenetic TreeCladograms can be flipped at nodes, show samerelationships 42. Fig. 26-13One can date divergence times with molecular clock and fossilsDrosophilaLanceletZebrafishFrogChickenHumanMouseCENOZOIC65.5 PresentMESOZOIC251Millions of years agoPALEOZOIC542 43. Relationship = recency of common ancestryi.e., taxa sharing a common ancestormore recent in time are more closely relatedthan those sharing common ancestors moredistant in time. 44. Example: Are fish more closely related to sharks or tohumans? 45. Shark Fish HumansTIME 46. Shark Fish HumansTIMEcommon ancestor ofFish and Humanscommon ancestor ofSharks, Fish, and Humans 47. monophyleticgroupVertebrataOsteichthyesShark Fish HumansTIMEcommon ancestor ofFish and Humanscommon ancestor ofSharks, Fish, and Humans 48. Example: Are crocodyles more closely related to lizardsor to birds? 49. Lizards &Snakes Turtles Crocodyles Birds 50. "Reptilia"Lizards &Snakes Turtles Crocodyles Birds 51. Paraphyletic group Consist of common ancestor but not alldescendents Paraphyletic groups are unnatural, distortevolutionary history, and should not berecognized. 52. "Reptilia"Lizards &Snakes Turtles Crocodyles Birds 53. Reptilia here paraphyletic"Reptilia"Lizards &Snakes Turtles Crocodyles Birds 54. Re-defined Reptilia monophyleticLizards &ReptiliaTurtles Snakes Crocodyles Birds 55. DinosaursLizards &Snakes Turtles Crocodyles Birds Reptilia 56. Importance of a name:Did humans evolve from apes? 57. Orangatan Gorilla Chimpanzees Humans 58. HominidaePongidaeGreat ApesOrangatan Gorilla Chimpanzees Humans 59. Pongidae orHominidaePongidaeHominidaeGreat ApesOrangatan Gorilla Chimpanzees Humans 60. Pongidae orHominidaeHominidaeOrangatan Gorilla Chimpanzees Humans 61. Pongidae orHominidaeHominidaeOrangatan Gorilla Chimpanzees Humans 62. We are human, butwe are also apes. We share unique human features. We also share features with other apes(and with other animals, plants, fungi,bacteria, etc.). Humans didnt evolve from apes, humansare apes. 63. Importance of systematics & evolution:1) Foundation of biology - study of biodiversity2) Basis for classification of life3) Gives insight into biological processes:speciation processesadaptation to environment4) Can be aesthetically/intellectually pleasing! 64. E.g., schistosomiasis 65. Schistosomiasis:knowledge of speciesdiversity and evolutionaryhistory of primary host canaid in controlling parasite(Schistosoma, a fluke)Phylogeny of Oncomelania snails 66. All of life is interconnectedby descent.TAXAA B C D E FTIMElineageor cladeCladogram or Phylogenetic Tree 67. There are no higher orlower species.TAXAA B C D E FTIMElineageor cladeCladogram or Phylogenetic Tree