Lecture 12: EvolutionBiological Change Over TimeMicroevolutionary ProcessesMicroevolutionPowerPoint PresentationGenotypes, Phenotypes and Environmental EffectsGenetic Equilibrium Allele frequencies at a locus are not changingWhat happens when the rules are broken?Rule #1 No MutationVariation in the gene pool?Rule #2 No ImmigrationGene FlowRule #3 Survival or Reproductive AdvantagePillars of Natural SelectionBasics of Natural Selection Capacity and CompetitionSlide 16Results of Natural SelectionDirectional SelectionStabilizing SelectionDisruptive SelectionResistanceExample: Pesticide ResistanceSlide 23Slide 24Slide 25Slide 26Slide 27Insects Evolve at a High RateSexual SelectionBalanced PolymorphismSickle-Cell Trait: Heterozygote AdvantageRule #4 Large PopulationGenetic DriftSlide 35Large Population SimulationBottleneck SimulationRule #5 Random MatingInbreedingSlide 40Macroevolution and SpeciationBiological Species ConceptMorphology & SpeciesVariable MorphologyIsolation and DivergenceReproductive Isolation Can’t allow gene flowSpeciationAllopatric EffectExtensive Divergence Prevents InbreedingHawaiian IslandsHawaiian HoneycreepersSlide 52Speciation without a BarrierSpeciation by PolyploidyPossible Evolution of WheatParapatric SpeciationAre We All Related?Patterns of Change in a LineageEvolutionary TreesGradual ModelPunctuation ModelAdaptive RadiationSlide 63ExtinctionWho Survives?Critics of EvolutionJones vs. Smith Returning a cracked kettleSlide 68Slide 69Mechanism of EvolutionSlide 71Factors that cause changeSlide 73Lecture 12: EvolutionLecture 12: EvolutionKey terms: Key terms: Reading:Reading:Ch16: MicroevolutionCh16: MicroevolutionCh17:SpeciationCh17:SpeciationCh18:MacroevolutionCh18:MacroevolutionBiological Change Over Biological Change Over TimeTimeMicroevolutionMicroevolutionChanges with in Changes with in speciesspeciesWell defined Well defined mechanismmechanismEasily observedEasily observedBased on Based on selectionselectionMacroevolutionMacroevolutionChange from one Change from one species to anotherspecies to anotherUndefined Undefined mechanismmechanismInterpretation of:Interpretation of:–CladisticsCladistics–Fossil recordFossil record–Geological dataGeological dataMicroevolutionary Microevolutionary ProcessesProcessesDrive a population away from Drive a population away from genetic equilibriumgenetic equilibriumSmall-scale changes in allele Small-scale changes in allele frequencies brought about by:frequencies brought about by:–Natural selectionNatural selection–Gene flowGene flow–Genetic driftGenetic driftMicroevolutionMicroevolutionGeneticsGeneticsMicroevolution Microevolution changes a population changes a population not individualsnot individualsTraits in a population Traits in a population vary among vary among individualsindividualsMicroevolution is Microevolution is change in frequency change in frequency of traitsof traitsNatural SelectionNatural SelectionReproductive success Reproductive success for winning for winning phenotypesphenotypesActs directly on Acts directly on phenotypes and phenotypes and indirectly on genotypesindirectly on genotypesThe first changed The first changed individual has no individual has no advantageadvantageThe Gene PoolThe Gene PoolAll of the genes in the All of the genes in the population population Genetic resource that Genetic resource that is shared (in theory) is shared (in theory) by all members of by all members of populationpopulationPhenotype VariationPhenotype VariationTwo copies of each gene (2 Two copies of each gene (2 alleles)alleles)Inherit different allele Inherit different allele combinationscombinationsDifferent combinations= Different combinations= different phenotypesdifferent phenotypesInherit genotype, NOT Inherit genotype, NOT phenotypesphenotypesVariation is inheritedVariation is inheritedFig. 10.18, p. 166Genotypes, Phenotypes Genotypes, Phenotypes and Environmental Effectsand Environmental EffectsHimalayan rabbit experimentHimalayan rabbit experiment1.1.Pluck harePluck hare2.2.Grow hair with cold packGrow hair with cold packRabbits share genotype but phenotype Rabbits share genotype but phenotype is dependent on environmental is dependent on environmental conditionsconditionsGenetic EquilibriumGenetic Equilibrium Allele frequencies at a locus are not Allele frequencies at a locus are not changingchanging 5 Rules for Equilibrium5 Rules for Equilibrium1.1.No mutationNo mutation2.2.No immigration/ No immigration/ emigrationemigration3.3.Gene doesn’t affect Gene doesn’t affect survival or reproductionsurvival or reproduction4.4.Large populationLarge population5.5.Random matingRandom matingInterpreteInterpreteddNo VariationNo VariationNo VariationNo VariationNo selectionNo selectionNo selectionNo selectionNo selectionNo selectionWhat happens when What happens when the rules are broken?the rules are broken?Rule #1 No MutationRule #1 No MutationBiological information changesBiological information changesEach gene has own mutation Each gene has own mutation raterate–What determines rates?What determines rates?Effect of mutations on selectionEffect of mutations on selection–LethalLethal–Neutral Neutral –Advantageous AdvantageousVariation in the gene Variation in the gene pool? pool? 1.1.RecombinationRecombination•Crossing over at meiosis ICrossing over at meiosis I2.2.Independent assortmentIndependent assortment•Meiosis II (haploid germ cells)Meiosis II (haploid germ cells)3.3.FertilizationFertilization•Haploid + haploid = diploidHaploid + haploid = diploid4.4.Changes in chromosome Changes in chromosome number or structurenumber or structure5.5.Mutations Mutations Reorganizing InformationChanging InformationRule #2 No Rule #2 No ImmigrationImmigrationImmigration from a separate, Immigration from a separate, segregated populationssegregated populations–New variationNew variationAllelesAllelesMutationsMutationsEffects of immigrationEffects of immigration–Shifts allele frequencyShifts allele frequency–Introduces new mutations through Introduces new mutations through breedingbreedingGene FlowGene FlowPhysical flow of alleles into a Physical flow of alleles into a populationpopulationTends to keep the gene pools of Tends to keep the gene pools of populations similarpopulations similarCounters the differences Counters the differences between two populations that between two
View Full Document