Chapter 17 Section 1: Genetic Variation
Chapter 17 Section 1:Genetic VariationAdapted from Holt Biology 2008
Chapter 17 Section 1:Genetic VariationKey VocabularyTermsAdapted from Holt Biology 2008
Population geneticsThe study of thefrequency andinteraction ofalleles and genesin populationsAdapted from Holt Biology 2008
Normal Distribution1. A distribution ofnumerical data whosegraph forms a bellshaped curve that issymmetrical about themean.2. A line graph showingthe general trends in aset of data of whichmost values are nearthe mean (average).Adapted from Holt Biology 2008
PolygenicA character that is influenced by several genesAdapted from Holt Biology 2008Adapted from Holt Biology 2008
DistributionAn overview of therelative frequencyand range of a set ofvalues.Mathematically, adistribution is a tallyor a histogram with asmooth line to showthe overall pattern ofthe values.Adapted from Holt Biology 2008Adapted from Holt Biology 2008
Bell curveA symmetrical frequency curveAdapted from Holt Biology 2008Adapted from Holt Biology 2008
Gene poolThe particularcombination ofalleles in apopulation at anyone point in time.Adapted from Holt Biology 2008Adapted from Holt Biology 2008
Chapter 17Section 1:Genetic VariationNotesAdapted from Holt Biology 2008Adapted from Holt Biology 2008
PopulationGeneticsAdapted from Holt Biology 2008Adapted from Holt Biology 2008
Population Genetics, continuedMicroevolution canbe studied byobserving changes inthe numbers andtypes of alleles inpopulations, calledpopulation genetics.Adapted from Holt Biology 2008Adapted from Holt Biology 2008
The fields of ecology,genetics, andevolutionary theoryare brought togetherto understand howgenetic changes inpopulations result inchanges to speciesover timeAdapted from Holt Biology 2008Adapted from Holt Biology 2008
Population Genetics, continuedThe link frommicroevolution tomacroevolution —speciation — can bestudied in detail.Adapted from Holt Biology 2008Adapted from Holt Biology 2008
YOUR TURNThink, Write, Share & Re-writeWhat do we now know aboutheredity that Darwin did notknow?Adapted from Holt Biology 2008
PhenotypicVariationAdapted from Holt Biology 2008Adapted from Holt Biology 2008
Phenotypic VariationThe variety ofphenotypes thatexists for a givencharacteristicdepend on howmany genes affectit.Adapted from Holt Biology 2008Adapted from Holt Biology 2008
YOUR TURNThink, Write, Share & Re-writeWhat kinds of variation can beseen in this classroom?Adapted from Holt Biology 2008
Phenotypic VariationPolygenic charactersare influenced byseveral genes.Examples includehuman eye color,skin color, andheight.Adapted from Holt Biology 2008Adapted from Holt Biology 2008
Biologists study polygenic phenotypes bymeasuring each individual in thepopulation and then analyzing thedistribution of the measurements.Adapted from Holt Biology 2008Adapted from Holt Biology 2008
Phenotypic Variation, continuedA normal distribution, or bell curve, is onethat tends to cluster around an averagevalue in the center of the range.Adapted from Holt Biology 2008Adapted from Holt Biology 2008
YOUR TURNThink, Write, Share & Re-writeWhy do polygenic characters varyso much?Adapted from Holt Biology 2008
4MeasuringVariation andChangeAdapted from Holt Biology 2008Adapted from Holt Biology 2008
Measuring Variation and ChangeThe particularcombination ofalleles in apopulation at anyone point in timemakes up a genepool.Adapted from Holt Biology 2008Adapted from Holt Biology 2008
Measuring Variation and ChangeGenetic variation and change aremeasured in terms of the frequency ofalleles in the gene pool of a population.Adapted from Holt Biology 2008Adapted from Holt Biology 2008
A frequency is theproportion or ratioof a group that is ofone type. To studygenetic change, thefrequency of eachallele in apopulation can betracked over time.Adapted from Holt Biology 2008Adapted from Holt Biology 2008
5Sources of Genetic VariationEvolution cannotproceed if there is novariation. The majorsource of new allelesin naturalpopulations ismutation in germcells.Adapted from Holt Biology 2008
Sources of Genetic VariationMutation generatesnew alleles at a slowrate.Only mutations ingerm cells (egg andsperm) are passedon to offspring.Adapted from Holt Biology 2008Adapted from Holt Biology 2008
YOUR TURNThink, Write, Share & Re-writeWhy do polygenic characters varyso much?Adapted from Holt Biology 2008
SummaryMicroevolution can bestudied by observingchanges in thenumbers and types ofalleles in populations.Adapted from Holt Biology 2008Adapted from Holt Biology 2008
Biologists study polygenic phenotypes bymeasuring each individual in thepopulation and then analyzing thedistribution of the measurements.Adapted from Holt Biology 2008Adapted from Holt Biology 2008
SummaryGenetic variationand change aremeasured in termsof the frequency ofalleles in the genepool of apopulation.Adapted from Holt Biology 2008Adapted from Holt Biology 2008
SummaryThe major sourceof new alleles innaturalpopulations ismutation in germcells.Adapted from Holt Biology 2008Adapted from Holt Biology 2008
Chapter 17 Section 2:Genetic ChangeAdapted from Holt Biology 2008
Chapter 17 Section 2:Genetic ChangeKey VocabularyTermsAdapted from Holt Biology 2008
Genetic EquilibriumA state in which theallele frequencies ofa population remainin the same ratiosfrom one generationto the nextAdapted from Holt Biology 2008
Hardy-Weinberg PrinciplePredicts that thefrequencies ofalleles andgenotypes in apopulation won’tchange unless atleast 1of 5 forcesacts upon thepopulation.gene flow, nonrandommating, genetic drift,mutation, and naturalselectionAdapted from Holt Biology 2008
Gene flowOccurs when genes are added to orremoved from a populationAdapted from Holt Biology 2008
InbreedingWhich individuals either self-fertilize ormate with others like themselvesAdapted from Holt Biology 2008
Nonrandom matingMating that has not occurred due tochanceAdapted from Holt Biology 2008
YOUR TURNThink, Write, Share & Re-writeWhat can cause gene flow?Adapted from Holt Biology 2008
Directional selectionIn directionalselection, the“peak” of a normaldistribution movesin one directionalong its rangeAdapted from Holt Biology 2008
Stabilizing selectionIn stabilizingselection, the bellcurve shapebecomesnarrower.Adapted from Holt Biology 2008
Disruptive selectionIn disruptive selection, the bell curve is“disrupted” and pushed apart into twopeaks.Adapted from Holt Biology 2008
Chapter 17Section 2:Genetic ChangeNotesAdapted from Holt Biology 2008
Equilibrium andChangeAdapted from Holt Biology 2008
Equilibrium and ChangeA population inwhich no geneticchange occurredwould be in a stateof geneticequilibrium.Adapted from Holt Biology 2008
Measuring ChangeGenetic change in apopulation can bemeasured as achange in genotypefrequency or allelefrequency.Adapted from Holt Biology 2008
Measuring ChangeA change in onedoesn’t necessarilymean a change inthe other.Adapted from Holt Biology 2008
The Hardy-Weinberg principlePredicts that the frequencies of alleles andgenotypes in a population will not changeunless at least one of five forces acts upon thepopulation.Adapted from Holt Biology 2008
The Hardy-Weinberg principleThe forces that can act against geneticequilibrium are gene flow, nonrandommating, genetic drift, mutation, and naturalselection.Adapted from Holt Biology 2008
Forces of Genetic ChangeGene FlowOccurs when genes are added to orremoved from a population.Adapted from Holt Biology 2008
Forces of Genetic ChangeGene FlowGene flow can becaused by migration,the movement ofindividuals from onepopulation toanotherAdapted from Holt Biology 2008
Forces of Genetic ChangeNonrandom MatingIn sexually reproducing populations, anylimits or preferences of mate choice willcause nonrandom mating.Adapted from Holt Biology 2008
Forces of Genetic ChangeGenetic DriftChance events can cause rare alleles to belost from one generation to the next,especially when populations are small.Adapted from Holt Biology 2008
Forces of Genetic ChangeGenetic DriftSuch random effects on allele frequenciesare called genetic drift.Adapted from Holt Biology 2008
Forces of Genetic ChangeMutationCan add a new allele to a population.Adapted from Holt Biology 2008
Forces of Genetic ChangeNaturalSelectionNatural selectionacts to eliminateindividuals withcertain traitsfrom apopulation.Adapted from Holt Biology 2008
Forces of Genetic ChangeNatural SelectionAs individuals areeliminated, the allelesfor those traits maybecome less frequentin the population.Adapted from Holt Biology 2008
Forces of Genetic ChangeNatural SelectionThus, both allele and genotype frequenciesmay change.Adapted from Holt Biology 2008
Chapter 17 Section 2:Genetic ChangeSexualReproduction andevolutionAdapted from Holt Biology 2008
Sexual Reproduction andEvolutionSexualreproductioncreates chances torecombine allelesand thus increasevariation in apopulation.Adapted from Holt Biology 2008
Sexual Reproduction andEvolutionSexual reproduction creates the possibilitythat mating patterns or behaviors caninfluence the gene pool.Adapted from Holt Biology 2008
Sexual Reproduction andEvolutionFor example, inanimals, femalessometimes selectmates based on themale’s size, color,ability to gather food,or othercharacteristics.Adapted from Holt Biology 2008
Sexual Reproduction andEvolutionThis kind of behavioris called sexualselection and is anexample ofnonrandom mating.Adapted from Holt Biology 2008
Sexual Reproduction andEvolutionAnother example ofnonrandom mating isinbreeding, in whichindividuals eitherself-fertilize or matewith others likethemselves.Adapted from Holt Biology 2008
Sexual Reproduction andEvolutionInbreeding is morelikely to occur if apopulation is small.In a smallpopulation, allmembers are likelyto be closelyrelated.Adapted from Holt Biology 2008
YOUR TURNThink, Write, Share & Re-writeWhat is the genetic effect ofinbreeding?Adapted from Holt Biology 2008
Chapter 17 Section 2:Genetic ChangePopulation Size andEvolutionAdapted from Holt Biology 2008
Population Size and EvolutionPopulation size strongly affects theprobability of genetic change in apopulation.Adapted from Holt Biology 2008
Population Size and EvolutionAllele frequencies are more likely toremain stable in large populations thanin small populations.Adapted from Holt Biology 2008
Population Size and EvolutionGenetic drift is a strong force in smallpopulations and occurs when aparticular allele disappears.Adapted from Holt Biology 2008
Chapter 17 Section 2:Genetic ChangeNatural Selection& EvolutionAdapted from Holt Biology 2008
Natural selection is a result ofthe following facts: All populations have genetic variation. Individuals tend to produce moreoffspring than the environment cansupport. Populations depend upon thereproduction of individuals.Adapted from Holt Biology 2008
How Selection ActsNatural selectioncauses evolutionin populations byacting onindividuals.Adapted from Holt Biology 2008
Genetic Results of SelectionThe result of natural selection is thateach allele’s frequency may increase ordecrease depending on the allele’seffects on survival and reproduction.Adapted from Holt Biology 2008
Why Selection is LimitedThe key lessonthat scientists havelearned aboutevolution bynatural selection isthat theenvironment doesthe selecting.Adapted from Holt Biology 2008
Natural selection is indirectIt acts on genotypes by removingunsuccessful phenotypes from apopulation.Adapted from Holt Biology 2008
The Role of MutationOnly characteristics thatare expressed can betargets of naturalselection. If a mutationresults in rare recessivealleles, for example,selection cannotoperate against it.Adapted from Holt Biology 2008
The Role of MutationFor this reason,geneticdisorders (suchas cystic fibrosisin humans) canpersist inpopulations.Adapted from Holt Biology 2008
YOUR TURNThink, Write, Share & Re-writeHow can unfavorable allelespersist?Adapted from Holt Biology 2008
Patterns ofNatural SelectionAdapted from Holt Biology 2008
Patterns of Natural SelectionThree majorpatterns arepossible in the waythat naturalselection affects thedistribution ofpolygeniccharacters overtime.Adapted from Holt Biology 2008
These patterns are:– Directional selection– Stabilizing selection, &– Disruptive selection.Adapted from Holt Biology 2008
Directional SelectionIn directionalselection, the“peak” of anormaldistributionmoves in onedirection along itsrange.Adapted from Holt Biology 2008
Directional SelectionIn this case,selection acts toeliminate anextreme from arange ofphenotypes,making them lesscommon.Adapted from Holt Biology 2008
Stabilizing SelectionIn stabilizingselection, the bellcurve shapebecomes narrower.In this case,selection eliminatesindividuals that havealleles for anyextreme type.Adapted from Holt Biology 2008
Stabilizing SelectionStabilizingselection isvery commonin nature.Adapted from Holt Biology 2008
Disruptive SelectionIn disruptive selection, the bell curve is“disrupted” and pushed apart into twopeaks.Adapted from Holt Biology 2008
Disruptive SelectionIn this case,selection acts toeliminateindividuals withaverage phenotypevalues.Adapted from Holt Biology 2008
Kinds of SelectionAdapted from Holt Biology 2008
Natural Selection of Anole LizardSpeciesAdapted from Holt Biology 2008
YOUR TURNThink, Write, Share & Re-writeWhich form of selection increasesthe range of variation in adistribution?Adapted from Holt Biology 2008
SummaryThe Hardy-Weinberg principle predicts thatthe frequencies of alleles and genotypes in apopulation will not change unless at leastone of five forces acts upon the population.Adapted from Holt Biology 2008
SummaryThe forces that can act against geneticequilibrium are gene flow, nonrandommating, genetic drift, mutation, andnatural selection.Adapted from Holt Biology 2008
SummarySexualreproductioncreates thepossibility thatmating patternsor behaviors caninfluence thegene pool of apopulation.Adapted from Holt Biology 2008
SummaryAllele frequencies are more likely toremain stable in large populations thanin small populations.Adapted from Holt Biology 2008
SummaryNatural selection acts only to changethe relative frequency of alleles thatexist in a population. Natural selectionacts on genotypes by removingunsuccessful phenotypes from apopulation.Adapted from Holt Biology 2008
SummaryThree major patterns are possible inthe way that natural selection affects adistribution of polygenic charactersover time. These patterns aredirectional selection, stabilizingselection, and disruptive selection.Adapted from Holt Biology 2008
Chapter 17 Section 3:Population Genetics andSpeciationAdapted from Holt Biology 2008
Chapter 17 Section 3:Population Genetics andSpeciationKey VocabularyTermsAdapted from Holt Biology 2008
Reproductive IsolationA state in which aparticular set ofpopulations can nolonger interbreed toproduce futuregenerations ofoffspringAdapted from Holt Biology 2008
A taxonomicclassification belowspecies that groupsorganisms that live indifferent geographicalareas, differmorphologically fromother populations ofthe species, but caninterbreed with otherpopulations of thespeciesSubspeciesAdapted from Holt Biology 2008
Chapter 17 Section 3:Population Genetics and SpeciationNotesAdapted from Holt Biology 2008
Defining SpeciesScientists may usemore than onedefinition forspecies. Thedefinition useddepends on theorganisms and fieldof science beingstudied.Adapted from Holt Biology 2008
Defining SpeciesA species isgenerally definedas a group ofnaturalpopulations thatcan interbreedand usuallyproduce fertileoffspring.Adapted from Holt Biology 2008
Defining SpeciesThis definition isbased on thebiological speciesconcept.Adapted from Holt Biology 2008
Defining SpeciesOther definitions for species may be usedfor fossils or for organisms that reproduceasexually.Adapted from Holt Biology 2008
Defining SpeciesInstead of, or in addition to, the biologicalspecies concept, species may be definedbased on: their physical features, their ecological roles, or their genetic relatedness.Adapted from Holt Biology 2008
YOUR TURNThink, Write, Share & Re-writeWhy is a species hard to define?Adapted from Holt Biology 2008
Forming New SpeciesAdapted from Holt Biology 2008
Forming New SpeciesEach population of a single specieslives in a different place.Adapted from Holt Biology 2008
Forming New SpeciesIn each place, naturalselection acts uponeach population andtends to result inoffspring that arebetter adapted toeach specificenvironment.Adapted from Holt Biology 2008
Forming New SpeciesIf the environmentsdiffer, theadaptations maydiffer. This is calleddivergence and canlead to theformation of newspecies.Adapted from Holt Biology 2008
Forming New SpeciesSpeciation is the process of formingnew species by evolution frompreexisting species.Adapted from Holt Biology 2008
Speciation has occurred when the neteffects of evolutionary forces result in apopulation that has unique features and isreproductively isolated.Adapted from Holt Biology 2008
Reproductive IsolationReproductiveisolation is a statein which twopopulations can nolonger interbreedto produce futureoffspring.Adapted from Holt Biology 2008
Forming New SpeciesFrom this point on, the groups may besubject to different forces, so they willtend to diverge over time.Adapted from Holt Biology 2008
Forming New SpeciesThrough divergenceover time,populations of thesame species maydiffer enough to beconsideredsubspecies.Adapted from Holt Biology 2008
Forming New SpeciesSubspecies are simplypopulations that havetaken a step towardspeciation bydiverging in somedetectable way. Thismay only be apparentafter the passage oftime.Adapted from Holt Biology 2008
Mechanisms of IsolationAny of the following mechanisms maycontribute to the reproductive isolation ofpopulations: Geography Ecological Niche Mating Behavior and Timing Polyploidy HybridizationAdapted from Holt Biology 2008
YOUR TURNThink, Write, Share & Re-writeWhat mechanisms can isolatespecies?Adapted from Holt Biology 2008
Extinction:The End of SpeciesAdapted from Holt Biology 2008
Extinction: The End of SpeciesExtinction occurswhen a speciesfails to produceany moredescendants.Extinction, likespeciation, canonly be detectedafter it is complete.Adapted from Holt Biology 2008
Extinction: The End of SpeciesMore than 99%of all of thespecies thathave ever livedon earth havebecomeextinct.Adapted from Holt Biology 2008
Extinction: The End of SpeciesMany cases of extinction are the result ofenvironmental change.Adapted from Holt Biology 2008
Extinction: The End of SpeciesIf a species cannotadapt fast enoughto changes, thespecies may bedriven toextinction.Adapted from Holt Biology 2008
YOUR TURNThink, Write, Share & Re-writeWhen do we know that extinctionhas happened?Adapted from Holt Biology 2008
SummaryToday, scientists may use more than onedefinition for species. The definition useddepends on the organisms and field ofscience being studied.Adapted from Holt Biology 2008
SummarySpeciation has occurred when the neteffects of evolutionary forces result in apopulation that has unique features and isreproductively isolated.Adapted from Holt Biology 2008
SummaryThe species thatexist at anytime are the netresult of bothspeciation andextinction.Adapted from Holt Biology 2008
Gene pool The particular combination of alleles in a population at any one point in time. Adapted from Holt Biology 2008 . Adapted from Holt Biology 2008 Adapted from Holt Biology 2008 Chapter 17 Section 1: Genetic Variation Notes . Adapted from Holt Biology 2008 Adapted from Holt Biology
Part One: Heir of Ash Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapter 18 Chapter 19 Chapter 20 Chapter 21 Chapter 22 Chapter 23 Chapter 24 Chapter 25 Chapter 26 Chapter 27 Chapter 28 Chapter 29 Chapter 30 .
TO KILL A MOCKINGBIRD. Contents Dedication Epigraph Part One Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Part Two Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapter 18. Chapter 19 Chapter 20 Chapter 21 Chapter 22 Chapter 23 Chapter 24 Chapter 25 Chapter 26
DEDICATION PART ONE Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 PART TWO Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapter 18 Chapter 19 Chapter 20 Chapter 21 Chapter 22 Chapter 23 .
The Genetic Code and DNA The genetic code is found in a acid called DNA. DNA stands for . DNA is the genetic material that is passed from parent to and affects the of the offspring. The Discovery of the Genetic Code FRIEDRICH MIESCHER Friedrich Miescher discovered in white blood . The Discovery of the Genetic Code MAURICE WILKINS
About the husband’s secret. Dedication Epigraph Pandora Monday Chapter One Chapter Two Chapter Three Chapter Four Chapter Five Tuesday Chapter Six Chapter Seven. Chapter Eight Chapter Nine Chapter Ten Chapter Eleven Chapter Twelve Chapter Thirteen Chapter Fourteen Chapter Fifteen Chapter Sixteen Chapter Seventeen Chapter Eighteen
18.4 35 18.5 35 I Solutions to Applying the Concepts Questions II Answers to End-of-chapter Conceptual Questions Chapter 1 37 Chapter 2 38 Chapter 3 39 Chapter 4 40 Chapter 5 43 Chapter 6 45 Chapter 7 46 Chapter 8 47 Chapter 9 50 Chapter 10 52 Chapter 11 55 Chapter 12 56 Chapter 13 57 Chapter 14 61 Chapter 15 62 Chapter 16 63 Chapter 17 65 .
HUNTER. Special thanks to Kate Cary. Contents Cover Title Page Prologue Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapter
Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapter 18 Chapter 19 Chapter 20 . Within was a room as familiar to her as her home back in Oparium. A large desk was situated i
