how populations evolved

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HowPopulations volveObjectivesIntroduction Describe five adaptations hat help blue-footedboobies survive.Evidence f Evolution

13.1 Briefly describe hehistory of evolutionaryhought.13.1 Explain how Darwin'svoyageon theBeagle nfluenced is thinking.13.1 Describe he ideasand events hat resultedn Darwin's1859book.13.2 Explain how fossils orm, notingexamples f eachprocess.13.2 Explain how the fossil recordprovidessomeof the sftongestevidenceof evolution.13.3 Explain how biogeography, omparative natomy, omparative mbryology,and molecu-lar biology document volution.

Darwin'sTheoryand the ModernSynthesis13.4 Describe Darwin's assumptionsn developinghe concept f naturalselection.13.4 Explain how artificial selectionsupportsnaturalselection.L3.5 Describe two examplesof naturalselection hat are knownto occur. Note three keypoints about how naturalselectionworks.13.6 Define a populationand a species.13.6 Explain the significance f the modern ynthesis.13.7 Explain how microevolutionoccurs.

L3.8, 13.9 Explain the significanceof Hardy-Weinberg quilibriumto natural populationsand npublic-healthscience.13.10 Describe the five conditions equired or Hardy-Weinberg quilibrium.13.11 Explain how the bottleneckeffect, he foundereffect,gene low, and mutation nfluencemicroevolution.13.12 Explain how natural selection esults rom changesn geneticequilibrium.Variation and Natural Selection

13.13 Explain why only somevariation s heritable.Explainhowgeneticvariations measured.13.14 Explain how mutation andsexual ecombination roducegeneticvariation.13.14 Explain why multiple-drug cochails are more ikely to be effectiveagainstHW thansingle-drug reatments.13.15 Explain how genetic ariation s maintainedn populations.13.16 Explain what is meantby neutral ariation.13.17 Explain why geneticbottlenecks hreaten he survival of certainspecies.13.1E Define Darwinian fitness.Explainwhy survivalof the fittest can be misleading.13.19 Describe he threegeneraloutcomesf naturalselection.13.20 Define and compare ntrasexual electionand ntersexual election.13.21 List four reasonswhy natural selection annotproduceperfection.13.22 Explain why antibiotic esistanceasevolved.

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Chapter 13 How PopulationsEvolve l2l

KeyTermsevolutionaryadaptation artificial selection gene lowevolution population mutationfossil population genetics polymorphicdescentwith modification modern synthesis clinepaleontologist species heterozygoteadvantagefossil record gene pool neutralvariationbiogeography microevolution Darwinian fitnesscomparativeanatomy Hardy-Weinberg stabilizing selectionhomologousstructure equilibrium directionalselectioncomparativeembryology genetic drift diversifying selectionmolecularbiology bottleneck effect sexualdimorphismnatural selection founder effect

WordRootsbio- : life; geo- heEarth(biogeography:he study of the pastandpresent istributionof species)homo- = like, resemblinghomology: imilarity in characteristicsesulting rom a shared ncestry)muta- : change rnutation: changen the DNA of genes hat ultimatelycreates eneticdiversity)paleo- = ancientQtaleontology.'he scientific stttdy of fossils)poly- : many;morph- : form (polymorphism:he coexistencef trpoor more distinct ormsof indi-viduals n the samepopulation)

LectureOutlineIntroduction Clown,Fool,or SimplyWell-Adapted?

A. Review:Evolution is the central theme of biology. Evolutionary adaptation is a uni-versalcharacteristicf living things (seeModule 1.6).NOTE:More than any other idea in biology, evolutionary heory serveso tie thedisci-pline together. . Dobzhansky:Nothing in biology makes ense xceptn the ight ofevolution.

B. If you look at any organismcritically, you are first struckby the differencesrom otherorganisms.1. Further observationoften reveals that an organism'seaturesshow some elationshipto wherethe organism ives and what it does n its environment.2. The blue-footedbooby has enormouswebbed eet, a nostril that canclose underwater,preventingwater from entering the lungs, a glandthat secrets alt from con-sumedseawater,and a torpedolike body-all adaptationshat make ife on the seafeasible Figure13.0A and B).


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122 Instructor's Guide o Text ndMediaI. Evidence of Evolution

Module 13.1 A seavoyagehelpedDarwinframehis theoryof evolution.A. Awareness f eachorganism's daptationsndhow they fit theparticular onditionsofits environment elpsus appreciatehe naturalworld (Figure 13.1A).B. Early Greekphilosopherseldvariousviews.Anaximanderabout2500yearsago) sug-gestedhat life arose n waterand hat simplerormsprecededmore complex orms of

life. On the otherhand,Aristotle,who strongly nfluenced ater thinkers,believed hatspecieswerefixed and did not evolve.C. This latterview was advancedy the Judeo-Christianraditionthatall specieswerecreated n a singleact of creation bout6000yearsago.D. Buffon (mid-1700s) uggestedhat Earthwasmuch older and raised hepossibility hatdifferent species rose rom commonancestors,lthoughhe later arguedagainst hispoint.

NOTE: Buffon alsobelieved n catastrophism:ollowing naturaldisasters, omespeciesdie off, while populations f others already resentn lower numbers)ncreasen num-bers o becomemoredominant han heyhadbeen.E. Lamarck early 1800s)was he first to strongly upport he idea of evolution,but hebelieved he mechanismor changewas he nheritance f acquired haracteristics.F. Born in 1809,Darwin oinedthe crew of the surveyingship Beagleas a naturalist or aworld-encirclingoyagen 1831 Figure13.18).G. Comparisons f SouthAmerican ossilswith living species hereand ossilselsewhere,and observationsf organisms nd heir distributions n the GalSpagosslands,madeparticularlysffongmpressionsn him.H. Darwin was nfluenced y Lyell's Principles f Geology,whichpromotedhe idea ofcontinual,gradual, onsistent eological hange.I. After his retum,Darwin beganwork on anessay o documenthis observationsnd hisnew theory of evolution.J. In the mid-1850sWallace onceived ssentiallyhe same heory basedon his observa-tions n Indonesia.He contacted arwin,andpresentationsf both heir works weremade o the scientific ommunityn 1858.K. Darwin's On the Oigin of Species y Meansof Natural Selectionwaspublishedn1859and contains well-constructedrgumentor naturalselection, ackedby consid-erableevidence.He uses hephrasedescentwith modificationr which encapsulatesthe conceptof evolution.L. Darwin's view of evolution:Thehistoryof life is like a tree,with multiple branchingfrom the baseof the trunk to the tips of the branches.Specieson a givenbranch aremore closely interrelatedhan related o species n other branches.

Module 13.2 The studyof fossilsprovides trongevidenceor evolution.A. Hard parts, suchas skeletons nd shells, emainafter other organic matterhas decom-posed.Suchparts [email protected]).B. Petrified ossils orm by theslow mineralizationf organicmaterialsFigure13.28).C. Fossilizedmoldsof organismsorm whena coveredareadecays nd ills in with othersediment Figure 13.2C).D. Some ossils, suchas hoseof leaves,etain emnants f organicmatterwith molecularfragments hat can be analyzed Figure I3.2D).


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lU Instructor's Guide to Textand Media

C. Darwinhadpersonal nowledgeof and nterestn artificial selection Figure13.44,B)and comparedhe resultsof artificial selectiono the variationseenamongcloselyrelatedspeciesFigure13.4C).D. Tlvo importantpointscanbe drawnfrom Darwin's theoryof natural selection:

1. Ancestralspeciesgave ise to the diverse ife forms by transferof heritable raits tooffspring hat bestpromote eproduction. e called this descentwith modification.2. Overvastamountsof time, the gfadualaccumulation f changesn thecharacteris-tics among he individuals n a population ccurs.

Module 13.5 Connection:Naturalselection esultsn evolutionaryadaptations.A. Two good examples f the effectsof theprocess an be seenn the mantid. n bothcases, ewpopulations ave esulted,butnot new speciesFigure13.5A).B. Naturalselections a work in progress ndhas beendocumentedver 100 imes.Afrighteningcase hat is frequently epeateds the response f insects o insecticides.Those hat havethe predisposition or resistancewill srrvive andpasson this trait (agene) o their offspring Figure13.58).preview:The sameconceptwill be discussed ith bacteriaand he resistanceo antibi-

otic therapy(Module 13.22).C. Natural selection s regionaland timely.Populations end to evolve in responseo localenvironmental onditionsduring onetime period.A particularadaptationmay be point-less n thecontextof other ocalesor times.D. Significantevolutionary hange an occur n very shortperiodsof time.

Module 13.6 Populationsare the units of evolution.A. A poputation is a groupof individual organismsiving in the sameplace at the sametime.B. Evolution is measuredas the changen frequencyof a givencharacteristicwithin apopulationovera successionf generations.C. Darwin realized his, but he did not know aboutthe genetic mechanisms.D. During the 1920spopulation geneticswascombinedwith Darwinianprinciples nto acomprehensiveheory of evolutionknownasthe modenn synthesis.E. Centralto this synthesiss the sexualspecies oncept.A sexualspeciess a groupofpopulationswhose ndividualshavethepotential to interbreedandproduce ertile off-rp.iog. A given sexualspecieshas an overallrange, with concentrations f individualsin local populations.NOTE: This is the sameas the biological speciesconcept ntroduced n Chapter14.

Preview:Since he sexual biological)speciesonceptconcerns ctuallyor potentiallyinterbreedingpopulations, t is difficult to apply it to the fossil record.Anotherspeciesconcept hat is more readily applied to the fossil record is the evolutionaryspeciesconcept.

F. Opportgnities or breedingamongpopulationsof the samespecies ary,dependingonthe species ndon the extentof isolationof the populations.Modute13.7 Microevolutions changen a population's enepool over ime'

Review:Thebasicconcepts f Mendeliangenetics Chapter9)'A. A population'sgenepool consistsof all the alleles in all the individualsmaking up thepopulation.


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Chapter 13 How Populations Evolve 125B. Most gene oci are representedy two or moreallelesacross population,and ndivid-uals (of most eukaryotes)arrying wo allelescan be homozygous r heterozygousorthe locus.C. During microevolution, he relative requencies f the allelesgovemingcharacteristicschange.For example,hose nsectswith a gene hat confers esistanceo an insecticidewill outnumberhose nsectswithout this particulargene.Thus, he allele requency orinsecticideesistance ill be higher n fields sprayedwith insecticidehan n untreated

fields.Module 13.8 The genepool of a nonevolving opulation emains onstant vergenerations.

NOTE: This examples entirely arbitrary and will work with any numbers.Have stu-dentsverify this fact by trying other examples.A. Use the example f a hypothetical opulationof 500blue-footed oobies.Nonwebbedfeet (WWor Ww) aredominantover webbed feet (ww), and a singlegene(allelesI4zand w) governs he characteristic:320 have WW,160 have Ww and20 havelrw genotypes.B. The Hardy-Weinberg quationshows hat allele frequenciesarestable n a population

not undergoingmicroevolution:2 + Zpq * q' : 1. That s, thepopulations madeupof: homozygous ominantgenotypes@\ * heterozygousenotypes2pq) * homozy-gousrecessiveenotypesq'). Also note thatp : | - Q.NOTE: If you have he patiencet may be worth the effort of taking your studentsthrough the derivationof the Hardy-Weinbergequation.Using the examplegivenhere:There are only two allelesof this particular gene, hus their frequenciesmust sum o I(p + q: 1).Theprobabil i tyf WW sp X p: p2itheprobabil i tyofwis qx q:q2i therearetwo waysof beingheterozygous,Ww andwlt thus the frequencyof theheterozygotes 2pq. Continuing,many of your studentswill be familiar with the FOILmethodfrom their math classes; avethem apply it to the following: p + q : 1; since1 x I : l ( p + q ) ( p q ) = l . F o l l - i n g t h i s g i v e s u s p 2 +p q + q 2 : l .C. The frequencies f WW,Ww, andww in the first generation re0.64, 0.32, andO.04.Sinceblue-footedboobiesarediploid, there are 1000 alleles n the population, and theirfrequencies tep : 0.80 w andq : o.2o w (Figure13.88).D. If random matingsoccurbetweenvarious membersof this population, hen the laws ofprobabilitywill predict he geneticmakeupof the nextgenerationseeModule9.7).E. On average,he next generationwill havep x p llrflz individuals (: 0.64), (p x q) +(q x p) IUw ndividuals 2pq : 0.32,since hereare wo ways o getpq in a zygote,dependingon whether he q is in the sperm or in the egg), andq x q ww individuals(: 0.M) (Figure13.8C)'Theallele requenciesemain he same.

Module 13.9 Connection: he Hardy-Weinbergquation s useful n publichealthscience.A. Estimatingfrequencies f harmful alleles among he populationat large helpspublic

health scientistsassess ndprioritize their efforts.B. For example,f PKU occurs n one out of 10,000 abies q2 : 0.0001), henq : 0.01,p : O.99,and2pq(thefrequency f carrierheterozygotes) 0.0198.

NOTE: This exercise an be usedwith any of the frequenciesof genes rom Table 9.9.Module 13.L0 Five conditionsare required or Hardy-\ileinberg equilibrium.

NOTE: Hardy-Weinberg quilibrium rarely exists n naturalpopulations in this sensetcan be viewedas a control,Module 1.3),but understandinghe assumptionsehind tgivesus a basis or understandingow populations volve.


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126 Instructor's Guide to Tbxtand MediaA. The population s very large.B. The population s isolated no migrationof individuals, r gametes,nto or out of thepopulation).NOTE:No gene low (Module13.11).C. Mutationsdo not alter thegenepool.D Mating is random.E. All individualsareequal n reproductive uccessno naturalselection).NOTE: No fitness ifferencesModules13.11, 3.18)

Module 13.L1 Thereare several otentialcauses f microevolution.NOTE: Approachthis by askingyour studentso identify situations hat will violate theconditionsisted n Module13.10.

A. Genetic drift is a changen a genepool of a smallpopulationdue to chance.Theeffect of a loss of individualsfrom a population s muchgleaterwhen thereare fewerindividuals. The bottleneck effect is geneticdrift resulting rom a disaster hat reducespopulationsize(suchas he exampleof the elephant eals;Figure 13.11A,B). Thefounder effect is geneticdrift resultingfrom colonizationof a new areaby a smallnumber (evenone) of individuals (likely important n the evolutionof animalsandplants on the Galdpagosslands).Anothergoodexampleof the foundereffect isthe high rate of retinitis pigmentosaamong he residents f Tristanda Cunha(Figure13.11C).NOTE: Geneticdrift is evolutionby samplingerror.

B. Gene flow is a gain or loss of alleles from a populationdue to immigrationor emigra-tion of individualsor gametes.C. Mutations arerare events,but they do occurconstantly asoften asoneper gene ocusper lOs gametes).Mutationprovides he raw materialon whichothermechanismsfmicroevolutionwork. Mutation is rarely, f ever,directly responsibleor evolutionary

change.D. Nonrandommating is more often the case,particularly amonganimals,where choiceofmates s often an importantpart of behaviorbut doesnot changeallele frequencyandthereforedoesnot affect microevolution.E. Differential successn reproductions probably always he case or naturalpopulations.The resulting natural selections the factor that is likely to result n adaptivechangesoa genepool.

NOTE: Differential reproductivesuccesss measuredn terrnsof fitnessdifferences(Module13.18).Module 13.12 Adaptivechange esultswhen naturalselection psets eneticequilibrium.

A. The amountandkind of genetic variation n thepopulation imit the degreeof adapta-tion that can occur.III. Variation and Natural Selection

Module 13.13 Variation s extensiven mostpopulations.A. Variation in a single characteristic anbe caused y the effect of one or moregenesorfrom the action of the environmentnducingphenotypicchange.B. A population is polymorphic for a characteristicf two or moremorphs contrastingforms) arenoticeablypresent; hesemaybe visibleor biochemical haracteristics


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Chapter 13 How PopulationsEvolve 127(Figure13.13).Much of this variationcanbeattributed o polygenicnheritance.Review:Polygenicnheritances discussedn Module9.16.

C. Most populations xhibit geographic ariationn the distributionof characreristics.hisvariationmay showstratification r be clinal, varyingsmoothlyacross he population.D. Geneticvariationcan be measuredn two ways: irst, by determininghe average er-cent of gene oci that are heterozygousgene iversity);second, y determininghe

nucleotidediversityof DNA sequences.Module 13.14Connection:Mutationand sexual ecombinationenerateariation.A. Review:Mutation Module10.16) ndmeiosisespecially odules .16,8.17,and8.18).NOTE:Mutation s theultimatesource f all variation.B. Mutationsnormallyare harmful,but theymay mprovean organism's daptationo anenvironmenthat s changing.Organisms ith very shortgenerationpans,ike bacteria,canevolve apidly by mutationalone.C. Sexual ecombinationhuffleshe mixtureof alleles n diploidorganisms.ndependentassortment, rossingover,and random ertilizationof spermand egg all play a role.

Organismshat reproduce exually end o have onger ife spans, nd sexual ecombi-nation is necessaryo increase he variationstemmingrom singlemutations(Figure13.14) .Module 13.15 Overview:How naturalselection ffects ariation.

A. An ancestral opulations varied,with individuals avingcharacteristicsuited ormany typesof environments.B. Over successiveenerations,hose ndividualswith the characteristicsestsuited ortheenvironmenteavemore offspring.These haracteristicsncreasen the subsequentgenerations.C. Those ndividualswith characteristics ot suited or the environmenteavefewer off-spring.Thesecharacteristicsecreasen subsequentenerations.D. The effectsof recessive llelesare not oftendisplayedn diploidorganisms.Recessiveallelesmay be hidden from naturalselectionwhenthey are found in combinationwith a dominantallele.Thus, variation s retainedn a population ubject o selection.NOTE: Since suchvariation is hidden t takesmanygenerationso eliminate (if they areeliminatedat all) disadvantageousecessivelleles rom a population.Review:Cystic ibrosis s only expressedn individualswho are homozygousecessivefor this disorder Module9.9).E. Heterozygoteadvantage s a situation n which the heterozygotes favoredover eitherhomozygote. s a result,variations maintainedn thepopulation. n exampleof thisis the sickle-cellallelewhereonehomozygotes susceptibleo malaria, he otherhomozygote uffers rom sickle-celldisease, nd he heterozygotes resistanto malariaandnormallydoesnot suffer rom sickle-cell iseaseModule9.14).F. A secondmechanismhat promotesbalanced olymorphisms frequency-dependentselection. or example,f too many of one ype(or morph)of organisms presentn apopulation,hat ype will be selected gainst,educingtrat ype's otal numbers.

Module 13.16Not all geneticvariationmay be subjecto naturalselection.A. Somecharacteristicshowingneutral variation(suchas human ingerprints) pparentlyprovideno selective dvantageFigure13.16).


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128 Instructor's Guide to Tbxt and Media

B. The requency f thesecharacteristics ay changeas a result of geneticdrift, but notby naturalselection.C. It is impossibleo demonstratehat an allele bringsno benefit o an organism, nd tmaybe that somesupposedlyeutralvariationsprovidebenefits n someenvironments.

Module 13.17Connection: ndangeredpecies ften have educedvariation.A. This s becomingmoreand more of a problemas humanactivity (habitatdestruction,the ntroduction f exotic nonnative] pecies, nregulated unting) endangers ild pop-ulations, articularlyhose hatare small to beginwith.

NOTE:The consequencesf suchhumanactivityare discussedn Chapter38.B. Theres about0.04Vo eterozygosityn the gene oci of the SouthAfrican population fthe cheetah, nd .4Voheterozygosityn the EastAfrican population.Theseanimalssuffered ottlenecks ue o disease, unting, and drought.

NOTE:This is an extremelyhigh degreeof geneticuniformity-higher than somestrainsof highly inbred aboratorymice.C. Thehigh degree f heterozygosityxhibitedby cheetahs, oupledwith loss of habitat,leaveshe cheetah'suture n the wild open o question.

NOTE:Ask your studentsf cheetatrs hould be preservedby human ntervention.Sooner r later species o extinct;perhapst is thepreservation, ot the extinction, fthe cheetatr hat will be due to human nterference.Module 13.18Theperpetuationf genes efinesevolutionaryitness.

A. Emphasizehat t is the survival of genesandthe phenotypic traits expressed y thegenes, ot individual organisms,hat are important.It is the genes hat survivethroughthepassagef time, not the ndividualorganism(s),hat are mportant.B. Darwinian fitness s defined asthe relative contribution that an individual makes o thegene ool of the nextgeneration.

Module 13.19Thereare hreegeneraloutcomes f naturalselection Figure13.19).A. Stabilizing selection ends o n:urow the range n population variability towardsomeintennediateorm. This occurs n relatively stable environments.Preview:An exampleof stabilizing selection s the birth weight of humanbabies,whichtendso be in the 6.5-9-poundange Module27.17).

B. Directional selection ends o move the modal (most common)form toward oneof theexftemes. his is most commonduring times of environmentalchange,or whenorgan-isms ind themselvesn new habitats.Preview:A goodexampleof the effects of directional selectionon life history patternscanbe found in the discussionof guppiessubject o different selectivepressures(Module 5.7).

C. Diversifying selectionoccurswhenenvironmentalconditions are varied n a way thatfavorsboth extremes ver t}te ntermediate orm.Module L3.20Sexual selectionmay producesexualdimorphism.

A. Sexualdimorphism is illustrated by two examplesof secondarysexualcharacteristics.B. Competitionbetweenmales or the privilege to mate with a female may dependon thestrengthof the male and his superiorability compared o other males(Figure 13.20A).


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Chapter 13 How PopulationsEvolve

C. Othercharacteristicsuchasplumagen birds may actuallybe detrimentalo the sur-vival of the maledue o increasedisk of predators.The rewardof mateselection ueto a largerplumagehanothermales,however,may outweigh he potential isk factors(Figure13.208).Module13.21 Naturalselection annot ashionperfectorganisms.

A. There arefour reasons hat account or imperfectionsin organismsn spiteof naturalselection:1. Organisms re ocked nto historicalconstraints; aturedoesn'tstart rom scratcheach ime there s a need or change.2. Adaptations re oftencompromises;omeadaptationso changeprovidean advan-tagealongwith a disadvantage.3. Not all evolutions adaptive; ature'sways are not always n the best nterestof theorganismn question.4. Selection an only edit existingvariations;f an adaptationo changes needed ndnone s availablen a population,hatpopulationmay becomeextinct.

B. Natural selectionoperates n a better than basis and it would be unreasonableoexpectperfectionrom a processwith such imitations.

Module13.22 Connection: he evolutionof antibiotic esistancen bacteria s a serious ublichealthconcern.A. Antibiotics were first developedn the 1930sand becamestandardmedicalpractice orthe preventionof infectious diseases uring WWII.B. Forcesof evolution(naturalselection)have acceleratedhe development f antibiotic-resistant trainsof bacteria.

Review:Antibiotic resistances caried on plasmidsthat are easily transferredbetweenbacterial ells(Module12.2).C. Overuseand misuseof antibiotics hascontributed o the proliferationof antibiotic-

resistantsftainsof bacteria.D. Multidrug-resistant trainsof the organism hat causes uberculosis Mycobacteriumtuberculosis)have appeared t alarming rates n the United Statesand areravagingotherpartsof the world (Figure 13.22).

Class ctivitiesl. As pointed ut n Module13.9, heHardy-Weinbergquationplaysarole n publichealthscience.Thisrole canbe demonstrated y having students,working in groups,choosea health ssue hat hasa

genetic asise.g.,PKU, cystic ibrosis, ickle-celldisease, ay-Sachs, tc.)and seehow t appliesopublichealthplanning n thecommunity n which they ive. The currentandprojectedpopulationsizeof thecommunitymustbeconsidered hencompleting his exercise.2. Pointout hat one of the major healthcare criseshumansare acing is the development f antibiotic-resistant acteria.Ask your students ow many of them,when givenprescriptionantibiotics, inish theentireprescription. herewill, almost nevitably, be at leastone studentwho doesnot. Pointout howthiscontributeso the ncreasen thenumbersof antibiotic-resistant trainsof bacteria.Further,as dis-cussedn Chapter2,bacteia canexchangelasmids;hus,bacterianeverexposedo aparticularantibiotic anbe resistanto that antibioticasa resultof plasmidexchange.

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130 Instructor's Guide to Tbxtand Media

Transparency cetatesFigure13.18 The voyageof theBeagle 1831-1836).he nsets how youngCharles arwinandhis ship.Figure13.2H Basilosauru.r, nextinctwhalewhose ind egs ink livingwhaleswith their and-dwelling ancestorsFigure13.3A Homologousstructures:ertebrateforelimbsFigure13.38 Evolutionary elationships etween umans nd ive othervertebrates,ased n hemo-globincomparisonsFigure13.48 Five breedsof dogs all members f the same pecies),he esults f hundredso thou-sands f yearsof artificialselectionFigure 3.4C Fivedifferentspecies f canines,he esults f thousandso millionsof yearsof naturalselectionFigure13.58 Evolutionof insecticideesistancen insectpopulationsFigure13.8A Imaginaryblue-footed oobies,with andwithout oot webbingFigure13.88 Genepool of originalpopulation f boobiesFigure13.8C Genepool ofnext generation fboobiesFigure13.11A ThebottleneckeffectFigure13.14 Shuffiingallelesby sexual ecombinationFigure13.19 Threepossibleeffectsofnaturalselection n aphenotypicharacterLayer )Figure13.19 Threepossibleeffectsof naturalselection n aphenotypicharacterLayet2)Figure13.19 Threepossibleeffectsof naturalselection n aphenotypicharacterLayer3)

MediaSee he beginningof this book for a completedescriptionof all mediaavailable or instructorsand stu-dents.Animations and videos are available n the Campbell magePresentation ibrary. MediaActivitiesandThinking asa Scientist investigationsare availableon the studentCD-ROMand web site.Animations ndVideos FileNameDome-BackedortoiseVideo 13-01A-TortoiseVideo-B.movDome-BackedortoiseVideo 13-01A-TortoiseVideo-S.movGaldpagosslandsOverviewVideo 13-01B-GalapagosVideo-B.movGaldpagosslandsOverviewVideo 13-0lB-GalapagosVideo-S.movMarine guanaVideo l3-018-MarinelguanaVideo-B.movMarine guanaVideo l3-0lB-MarinelguanaVideo-S.movGaldpagos eaLion Video 13-0lB-SealionVideo-B.movGaldpagos eaLionVideo l3-0lB-SealionVideo-S.movGrandCanyonVideo 13-02G-GrandCanyonVideo-B.movGrandCanyonVideo 13-02G-GrandCanyonVideo-S.mov


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Activities ndThinkingasa ScientistWeb/CD Activity l3A: Darwin and the Galdpagos slandsWeb/CD Activity I3B: The Voyageof the Beagle: Danvin's TripAround the WorldWeb/CD Activity I3C: ReconstructingForelimbsWeb/CD Thinking as a Scientist: How Do Environmental

ChnngesAffect a Population?Biology Labs On-Line: EvolutionLabWeb/CD Thinking as a Scientist: How Can Frequencyof Alleles

Be Calculated?Web/CD Activity \3D: Causesof MicroevolutionBiology Labs On-Line: PopulationGenetic LabWeb/CD Activity l3Fl. Genetic Variation from SexualRecombinationWeb/CD Thinking as a Scientist: Connection:WhatAre the

Pattentsof Antibiotic Resistance

Chapter13 How PopulationsEvolve

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t3.413.513.81 3 . 1 11 3 . 1 113.r413.22

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how populations evolved

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