Maintenanceofvariation变异的维持

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1、GeneticVariation-ThefuelofnaturalselectionCampbelletal,chapter23PopulationsarepolymorphicNaturevs.NurtureSourceofvariationMaintenanceofvariationPopulationsarepolymorphicNaturevs.NurtureSourceofvariationMaintenanceofvariationPolymorphicpopulationsExampl

2、e:DarwinfinchesonGalapagosPolymorphicpopulationsExample:LazulibuntingPolymorphicpopulationsExample:SwallowtailbutterflyPopulationsarepolymorphicNaturevs.NurtureSourceofvariationMaintenanceofvariationNaturevs.NurturePhenotypicExpressionProteinGenome(blu

3、eprint)NatureEnvironmentNurtureIfoundthegenethatmakesusbelievealltraitsarebasedongenesNaturevs.NurtureGeneChromosomeGenomeGenepoolNaturevs.NurtureDiploidyThereare2copiesofeachgeneFatherMotherOffspring2identicalcopies=homozygotFatherMotherOffspring2diff

4、erentcopies=heterozygotNaturevs.NurtureGenotypeismorevariablethanphenotypeOnlygeneticvariationcountsforevolutionNaturevs.NurtureHowtoseparatethetwo?Example:AltitudinalgradientCommonGardenExp.GeneEnvironmentMixtureofbothPopulationsarepolymorphicNaturevs

5、.NurtureSourceofvariationMutationRecombinationMaintenanceofvariationSourceofGeneticVariation1.MutationChangein:DNAsequenceChromosomestructureNumberofChromosomesDueto:CopyingErrorsEnvironmentalfactorsSourceofGeneticVariation2.RecombinationReshufflingofc

6、hromosomesduringreproductionCrossingoverABCABCABCABCPopulationsarepolymorphicNaturevs.NurtureSourceofvariationMaintenanceofvariationSelectionHeterosisMaintenanceofVariation1.StabilisingselectionFavoursmeanovertailLossofvariationMaintenanceofVariation1.

7、StabilisingselectionExample:DarwinFinchesBillsizeForagingefficiencyMaintenanceofVariation2.DirectionalselectionOnetailisfavouredovertheotherTraitischangingovertimeMaintenanceofVariation2.DirectionalselectionExample:Heliconiusbutterflyonpassionflowervin

8、esPlant:ToxinInsect:EnzymesPlant:FalseeggsLeadstoanarmsracebetweenplantandinsectMaintenanceofVariation2.DirectionalselectionThearmsraceidealeadtoamoregeneralhypothesis:RedQueenHypothesis‘Ittakesyoualltherunningtostayinplace’Maintenanceo