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22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
22 descent with modification a darwinian view
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22 descent with modification a darwinian view

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  • Figure 22.2 The intellectual context of Darwin ’s ideas.
  • Figure 22.3 Formation of sedimentary strata with fossils.
  • Figure 22.4 Acquired traits cannot be inherited.
  • Figure 22.5 The voyage of HMS Beagle.
  • Figure 22.6 Three examples of beak variation in Galápagos finches.
  • Figure 22.7 “I think. . .”
  • Figure 22.8 Descent with modification.
  • Figure 22.9 Artificial selection.
  • Figure 22.12 Camouflage as an example of evolutionary adaptation.
  • Figure 22.15 Mammalian forelimbs: homologous structures.
  • Figure 22.16 Anatomical similarities in vertebrate embryos.
  • Figure 22.18 Convergent evolution.
  • Figure 22.19 Ankle bones: one piece of the puzzle.
  • Figure 22.20 The transition to life in the sea.
  • Transcript

    • 1. LECTURE PRESENTATIONSFor CAMPBELL BIOLOGY, NINTH EDITIONJane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson© 2011 Pearson Education, Inc.Lectures byErin BarleyKathleen FitzpatrickDescent with Modification:A Darwinian View of LifeChapter 22
    • 2. Overview: Endless Forms Most Beautiful• A new era of biology began in 1859 whenCharles Darwin published The Origin ofSpecies• The Origin of Species focused biologists’attention on the great diversity oforganisms© 2011 Pearson Education, Inc.
    • 3. • Darwin noted that current species aredescendants of ancestral species• Evolution can be defined by Darwin’sphrase descent with modification• Evolution can be viewed as both a patternand a process© 2011 Pearson Education, Inc.
    • 4. • Darwin’s ideas had deep historical rootsThe Darwinian revolution challengedtraditional views of a young Earthinhabited by unchanging species© 2011 Pearson Education, Inc.
    • 5. 1809179818121795183017901809 1831−36184418591870Lamarck publishes hishypothesis of evolution.Malthus publishes“Essay on the Principleof Population.”Hutton proposeshis principle ofgradualism.Charles Darwinis born.Darwin travels aroundthe world on HMSBeagle.The Galápagos IslandsDarwin writes hisessay on descentwith modification.On the Origin ofSpecies is published.While studying speciesin the Malay Archipelago,Wallace sends Darwinhis hypothesis of naturalselection.1858Cuvier publishes his extensivestudies of vertebrate fossils.Lyell publishesPrinciples of Geology.Figure 22.2
    • 6. Scala Naturae and Classification of Species• The Greek philosopher Aristotle viewedspecies as fixed and arranged them on ascala naturae• The Old Testament holds that species wereindividually designed by God and thereforeperfect© 2011 Pearson Education, Inc.
    • 7. • Carolus Linnaeus interpreted organismaladaptations as evidence that the Creator haddesigned each species for a specific purpose• Linnaeus was the founder of taxonomy, the branchof biology concerned with classifying organisms• He developed the binomial format for namingspecies (for example, Homo sapiens)© 2011 Pearson Education, Inc.
    • 8. Ideas About Change over Time• The study of fossils helped to lay thegroundwork for Darwin’s ideas• Fossils are remains or traces of organismsfrom the past, usually found in sedimentaryrock, which appears in layers or strata© 2011 Pearson Education, Inc.
    • 9. Figure 22.3Sedimentary rocklayers (strata)Younger stratumwith more recentfossilsOlder stratumwith older fossils
    • 10. • Paleontology, the study of fossils, was largelydeveloped by French scientist Georges Cuvier• Cuvier advocated catastrophism, speculatingfrom the fossil record that extinctions musthave been a common occurrence in the pastand were caused by catastrophes• Periodic catastrophes occurred in local areas,which were later repopulated by differentspecies immigrating from other areas© 2011 Pearson Education, Inc.
    • 11. • Geologists James Hutton and Charles Lyellperceived that changes in Earth’s surface canresult from slow continuous actions stilloperating today, a theory called gradualism• Lyell’s principle of uniformitarianism statesthat the mechanisms of change are constantover time• These views strongly influenced Darwin’sthinking© 2011 Pearson Education, Inc.
    • 12. Lamarck’s Hypothesis of Evolution• Lamarck hypothesized that species evolvethrough use and disuse of body parts and theinheritance of acquired characteristics• The mechanisms he proposed are unsupportedby evidence• However, he did propose the first theory ofevolution in 1809, the year Darwin was born© 2011 Pearson Education, Inc.
    • 13. Figure 22.4
    • 14. • Some doubt about the permanence of speciespreceded Darwin’s ideasDescent with modification by naturalselection explains the adaptations oforganisms and the unity and diversity of life© 2011 Pearson Education, Inc.
    • 15. Darwin’s Research• As a boy and into adulthood, Charles Darwinhad a consuming interest in nature• Darwin first studied medicine (unsuccessfully),and then theology at Cambridge University• After graduating, he took an unpaid position asnaturalist and companion to Captain RobertFitzRoy for a 5-year around the world voyageon the Beagle© 2011 Pearson Education, Inc.
    • 16. The Voyage of the Beagle• During his travels on the Beagle, Darwin collectedspecimens of South American plants and animals• He observed that fossils resembled living speciesfrom the same region, and living speciesresembled other species from nearby regions• He experienced an earthquake in Chile andobserved the uplift of rocks© 2011 Pearson Education, Inc.
    • 17. • Darwin was influenced by Lyell’s Principles ofGeology and thought that the earth was more than6000 years old• His interest in geographic distribution of specieswas kindled by a stop at the Galápagos Islandswest of South America• He hypothesized that species from South Americahad colonized the Galápagos and speciated onthe islands© 2011 Pearson Education, Inc.
    • 18. Figure 22.5Darwin in 1840,after his returnfrom thevoyageTheGalápagosIslandsNORTHAMERICAATLANTICOCEANPACIFICOCEANPACIFICOCEANPintaMarchenaGenovesaEquatorChileSantiagoDaphneIslandsFernandinaIsabela SantaCruzSantaFe SanCristobalEspañolaKilometers0 20 40 FlorenzaPinzónSOUTHAMERICAAFRICAEUROPEGreatBritainHMS Beagle in portEquatorPACIFICOCEANMalay ArchipelagoAUSTRALIATasmaniaNewZealandBrazilArgentinaCape HornAndesMtns.Cape ofGood Hope
    • 19. Darwin’s Focus on Adaptation• In reassessing his observations, Darwinperceived adaptation to the environment andthe origin of new species as closely relatedprocesses• From studies made years after Darwin’svoyage, biologists have concluded that this iswhat happened to the Galápagos finches© 2011 Pearson Education, Inc.
    • 20. Figure 22.6Cactus eater. The long,sharp beak of thecactus ground finch(Geospiza scandens)helps it tear and eatcactus flowers andpulp.Insect eater. The green warbler finch(Certhidea olivacea) uses its narrow,pointed beak to grasp insects.Seed eater. The largeground finch (Geospizamagnirostris) has a largebeak adapted for crackingseeds that fall from plantsto the ground.
    • 21. • In 1844, Darwin wrote an essay on naturalselection as the mechanism of descent withmodification, but did not introduce his theorypublicly• Natural selection is a process in which individualswith favorable inherited traits are more likely tosurvive and reproduce• In June 1858, Darwin received a manuscript fromAlfred Russell Wallace, who had developed atheory of natural selection similar to Darwin’s• Darwin quickly finished The Origin of Species andpublished it the next year© 2011 Pearson Education, Inc.
    • 22. The Origin of Species• Darwin explained three broad observations:– The unity of life– The diversity of life– The match between organisms and theirenvironment© 2011 Pearson Education, Inc.
    • 23. Descent with Modification• Darwin never used the word evolution in thefirst edition of The Origin of Species• The phrase descent with modificationsummarized Darwin’s perception of the unityof life• The phrase refers to the view that allorganisms are related through descent froman ancestor that lived in the remote past© 2011 Pearson Education, Inc.
    • 24. • In the Darwinian view, the history of life islike a tree with branches representing life’sdiversity• Darwin’s theory meshed well with thehierarchy of Linnaeus© 2011 Pearson Education, Inc.
    • 25. Figure 22.7
    • 26. Figure 22.8Hyracoidea(Hyraxes)Sirenia(Manateesand relatives)†Deinotherium†Mammut†Platybelodon†Stegodon†MammuthusElephas maximus(Asia)Loxodonta africana(Africa)Loxodonta cyclotis(Africa)†Moeritherium†Barytherium60Millions of years ago34 24 5.5 21040Years ago
    • 27. Natural Selection and Adaptation• Evolutionary biologist Ernst Mayr has dissectedthe logic of Darwin’s theory into three inferencesbased on five observations
    • 28. • Observation #1: For any species, population sizeswould increase exponentially if all individuals thatare born reproduced successfully• Observation #2: Populations tend to be stable insize, except for seasonal fluctuations• Observation #3: Resources are limited• Inference #1: Production of more individuals thanthe environment can support leads to a strugglefor existence among individuals of a population,with only a fraction of their offspring surviving
    • 29. • Observation #4: Members of a population varyextensively in their characteristics; no twoindividuals are exactly alike
    • 30. • Observation #5: Much of this variation is heritable• Inference #2: Survival depends in part on inheritedtraits; individuals whose inherited traits give thema high probability of surviving and reproducing arelikely to leave more offspring than other individuals• Inference #3: This unequal ability of individuals tosurvive and reproduce will lead to a gradualchange in a population, with favorablecharacteristics accumulating over generations
    • 31. Artificial Selection, Natural Selection, andAdaptation• Darwin noted that humans have modifiedother species by selecting and breedingindividuals with desired traits, a processcalled artificial selection© 2011 Pearson Education, Inc.
    • 32. Figure 22.9BrusselssproutsKaleSelectionfor leavesSelection foraxillary (side)budsSelection forapical (tip) budCabbageBroccoliKohlrabiWild mustardSelectionfor stemsSelectionfor flowersand stems
    • 33. • Darwin was influenced by Thomas Malthus,who noted the potential for human populationto increase faster than food supplies andother resources• If some heritable traits are advantageous,these will accumulate in a population overtime, and this will increase the frequency ofindividuals with these traits• This process explains the match betweenorganisms and their environment© 2011 Pearson Education, Inc.
    • 34. Natural Selection: A Summary• Individuals with certain heritable characteristicssurvive and reproduce at a higher rate thanother individuals• Natural selection increases the adaptation oforganisms to their environment over time• If an environment changes over time, naturalselection may result in adaptation to these newconditions and may give rise to new species© 2011 Pearson Education, Inc.
    • 35. Figure 22.12(a) A flower mantid in Malaysia (b) A leaf mantid in Borneo
    • 36. • Note that individuals do not evolve;populations evolve over time• Natural selection can only increase ordecrease heritable traits that vary in apopulation• Adaptations vary with different environments• Natural selection does not create new traits,but edits or selects for traits already present inthe population• The local environment determines which traitswill be selected for or selected against in anyspecific population© 2011 Pearson Education, Inc.
    • 37. Evolution is supported by an overwhelmingamount of scientific evidence• New discoveries continue to fill the gapsidentified by Darwin in The Origin of Species© 2011 Pearson Education, Inc.
    • 38. Homology• Homology is similarity resulting from commonancestry© 2011 Pearson Education, Inc.
    • 39. Anatomical Homologies• Homologous structures are anatomicalresemblances that represent variations on astructural theme present in a common ancestor© 2011 Pearson Education, Inc.
    • 40. Figure 22.15HumerusRadiusUlnaCarpalsMetacarpalsPhalangesHuman Cat Whale Bat
    • 41. • Comparative embryology reveals anatomicalhomologies not visible in adult organisms© 2011 Pearson Education, Inc.
    • 42. Figure 22.16PharyngealpouchesPost-analtailChick embryo (LM) Human embryo
    • 43. Molecular Homologies• Examples of homologies at the molecularlevel are genes and proteins shared amongorganisms inherited from a common ancestor© 2011 Pearson Education, Inc.
    • 44. LE 22-16Percent of Amino Acids That AreIdentical to the Amino Acids in aHuman Hemoglobin Polypeptide100%95%87%69%54%14%Rhesus monkeySpeciesHumanMouseChickenFrogLamprey
    • 45. A Different Cause of Resemblance:Convergent Evolution• Convergent evolution is the evolution ofsimilar, or analogous, features in distantlyrelated groups• Analogous traits arise when groupsindependently adapt to similar environmentsin similar ways• Convergent evolution does not provideinformation about ancestry© 2011 Pearson Education, Inc.
    • 46. Figure 22.18SugargliderFlyingsquirrelNORTHAMERICAAUSTRALIA
    • 47. The Fossil Record• The fossil record provides evidence of theextinction of species, the origin of new groups,and changes within groups over time© 2011 Pearson Education, Inc.
    • 48. Figure 22.19Most mammals Cetaceans and even-toed ungulates(a) Canis (dog) (b) Pakicetus (c) Sus (pig) (d) Odocoileus (deer)Figure 22.19 Ankle bones: one piece of the puzzle. Comparing fossils and present- day examples of theastragalus (a type of ankle bone) provides one line of evidence that cetaceans are closely related to even-toed ungulates. (a) In most mammals, the astragalus is shaped like that of a dog, with a double hump onone end (indicated by the red arrows) but not at the opposite end (blue arrow). (b) Fossils show that theearly cetacean Pakicetus had an astragalus with double humps at both ends, a unique shape that isotherwise found only in even-toed ungulates, as shown here for (c) a pig and (d) a deer.
    • 49. • Fossils can document important transitions– For example, the transition from land to seain the ancestors of cetaceans© 2011 Pearson Education, Inc.
    • 50. Figure 22.20Othereven-toedungulatesHippopotamuses†Pakicetus†Rodhocetus†DorudonLivingcetaceansCommonancestorof cetaceansMillions of years ago70 Key60 50 40 30 20 10 0 Pelvis TibiaFemur Foot
    • 51. Biogeography• Biogeography, the geographic distribution ofspecies, provides evidence of evolution• Earth’s continents were formerly united in asingle large continent called Pangaea, but havesince separated by continental drift• An understanding of continent movement andmodern distribution of species allows us topredict when and where different groupsevolved• The Wallace Line is an example© 2011 Pearson Education, Inc.

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