Modern Synthetic Theory of Evolution - Vedantu

The Modern Synthetic theory of Evolution is described in terms of genetic changes happening in the populations that lead to the development of new species. BiologyBiologyModernSyntheticTheoryofEvo...ModernSyntheticTheoryofEvolutionBiologyStudyMaterialBiologytop10ImportantTopicsBiologySyllabusBiologyQuestionPapersBookonlinedemoNCERTSolutionsNCERTSolutionsClass12BiologyNCERTSolutionClass11BiologyNCERTSolutionsforClass10ScienceNCERTSolutionsforClass9ScienceNCERTSolutionsforClass8ScienceNCERTSolutionsforClass7ScienceNCERTSolutionsforClass6ScienceNCERTSolutionsforClass5EVSNCERTSolutionsforClass4EVSNCERTSolutionsforClass3EVSNCERTNotesClass12BiologyNotesClass11BiologyNotesClass10ScienceNotesClass9ScienceNotesClass8ScienceNotesClass7ScienceNotesClass6ScienceNotesNCERTImportantQuestionImportantQuestionsforClass12ScienceImportantQuestionsforClass11ScienceImportantQuestionsforClass10ScienceImportantQuestionsforClass9ScienceImportantQuestionsforClass8ScienceImportantQuestionsforClass7ScienceImportantQuestionsforClass6ScienceDifferenceBetweenWeatherandClimateScientificNamesofAnimalsandPlantsBacterialDiseasesinHumansEnzymesMCQsMCQsonGreenhouseEffectDeficiencyDiseasesConservationofBiodiversityDifferenceBetweenCyclicandNonCyclicPhotophosphorylationConservationofForestandWildlifeDifferenceBetweenNationalParkandWildlifeSanctuaryCBSEClass12BiologySyllabusCBSEClass11BiologySyllabusCBSEClass10ScienceSyllabusCBSEClass9ScienceSyllabusCBSEClass8ScienceSyllabusCBSEClass7ScienceSyllabusCBSEClass6ScienceSyllabusCBSEClass5EVSSyllabusCBSEClass4EVSSyllabusCBSEClass3EVSSyllabusISCClass12BiologySyllabusISCClass11BiologySyllabusICSEClass10BiologySyllabusICSEClass9BiologySyllabusICSEClass8BiologySyllabusICSEClass7BiologySyllabusICSEClass6BiologySyllabusCBSEClass12BiologyQuestionPapersCBSEClass12BiologyQuestionPaper2020CBSEClass12BiologyQuestionPaper2019CBSEClass12BiologyQuestionPaper2018CBSEClass12BiologyQuestionPaper2017CBSEClass12BiologyQuestionPaper2016CBSEClass12BiologyQuestionPaper2015CBSEClass12BiologyQuestionPaper2014CBSEClass12BiologyQuestionPaper2013CBSEClass10ScienceQuestionPapersCBSEClass10ScienceQuestionPaper2020CBSEClass10ScienceQuestionPaper2019CBSEClass10ScienceQuestionPaper2018CBSEClass10ScienceQuestionPaper2017CBSEClass10ScienceQuestionPaper2016CBSEClass10ScienceQuestionPaper2015CBSEClass10ScienceQuestionPaper2014CBSEClass10ScienceQuestionPaper2013CBSEClass10ScienceQuestionPaper2012CBSEClass10ScienceQuestionPaper2011CBSEClass10ScienceQuestionPaper2010CBSEClass10ScienceQuestionPaper2009CBSEClass10ScienceQuestionPaper2008CBSEClass10ScienceQuestionPaper2007ICSEClass10BiologyQuestionPapersICSEClass10BiologyQuestionPaper2020ICSEClass10BiologyQuestionPaper2019ICSEClass10BiologyQuestionPaper2018ISCClass12BiologyQuestionPapersISCClass12BiologyQuestionPaper2020ISCClass12BiologyQuestionPaper2019ISCClass12BiologyQuestionPaper2018Darwin'sTheoryofEvolutionbyNaturalSelectionTheModernSynthetictheoryofEvolutionisdescribedintermsofgeneticchangeshappeninginthepopulationsthatleadtothedevelopmentofnewspecies.Italsoclarifiesaboutthegeneticpopulation,genepool,andthegeneregularity.Theideasunderthissynthetictheoryofevolutioncontaintherecombinationorvariation,mutationheredity,naturalselectionandIsolation.FactorsofModernSyntheticTheoryofEvolutionRecombinationorVariationRecombinationiswhenthenewlyproducedgenotypesarederivedfromtheexistinggenes.Thegenecombinationshavingsimilarindividualswithtwotypesofalleles,mixingofthechromosomesinthecourseofsexualreproductionoftwoparentscreatenewindividuals,anexchangeofthechromosomalpairsofallelesthathappensduringmeiosis,knownascrossingover,yieldthenewformofgenecombinations.Chromosomalmutationslikeinversion,deletion,duplication,translocation,polyploidyallareresultingintherecombinationofgenes.Naturalselectionistypicallythemostpowerfulmechanismcausingevolutiontohappen.However,itonlychoosesamongthealreadyexistingvariationsinapopulation.Itdoesnotyieldnewgeneticvariationsbutitisalsoresponsibleformakinggeneticcombinations,whichwerenotfoundinearliergenerations.Spermandovaarebasicallydifferentfromsomaticcellsinthenumberofchromosomesthattheyhave.Bothmaleandfemalesexcellsusuallygetonlyhalfthenumberofparentchromosomes(23outof46inhumans).MutationThechangesthattakeplaceinthegeneisbecauseofthephenotypiceffectdifferentialasthemutation.Thiscreatesseveralnumbersofchangesthatmightbeharmful.Variousmutantformsofgenesarefallingtothenormalgenesinahomozygouscondition.Thesechangesarereasonvariationsinoffspring.Mutationscanhaveavarietyofeffects.Theycanoftenbeharmful.Othershavelittleeffect.Althoughveryhard,thechangeinDNAarrangementmayeventurnouttobeusefultotheorganism.Amutationthathappensinbodycellsthatarenotpassedthroughtosubsequentgenerationsiscalledasomaticmutation.Mutationstakeplaceinagameteorinacellandthatgivesrisetoothergametesbeingspecialduetotheimpactthenextgenerationmaynotharmtheadultatall.Suchchangesarenamedgerm-linemutationsbecausetheyoccurinacellusedinreproduction,givingthealterationachancetobecomemoreinovertime.Ifthemutationhasaharmfuleffectonthephenotypeoftheoffspring,themutationismentionedasageneticdisorder.Oneaftertheother,ifthemutationhasapositiveeffectonthefitnessoftheoffspring,itisknownasadaptation.Thus,allmutationsthatdisturbthefitnessoffuturegenerationsareagentsofevolution.Mutationsarevitalforevolution.Everygeneticaspectineveryorganismwas,primarily,theresultofamutation.Thenewgeneticvariantspreadswiththehelpofreproduction,anddifferentialreproductionisadefiningfactorofevolution.Itiseasytounderstandhowamutationthatletsanorganismtofeed,nurtureorreproducemoreefficientlycouldcausethemutantalleletobecomemoreabundantastimepassesby.Soonthepopulationmaybequiteecologicallyandphysiologicallydifferentfromtheoriginalpopulationthatisshortofadaptation.Evenharmfulmutationscancauseevolutionarychange,particularlyinsmallpopulations,byeliminatingindividualsthatmightbecarryingadaptiveallelesatothergenes. HeredityInhumans,eyecolorisanexampleofahereditarycharacteristic:anindividualcaninheritthe"brown-eyetrait"frommotherandfather.Inheritedcharactersareregulatedbygenesandthecompletegroupofgeneswithinanorganism'sgenomeisknownasitsgenotype.Thecompletegroupofobservablecharactersofthestructureandbehaviorofanorganismisknownbyitsphenotype.Thesetraitsarisefromtheinteractionofitsgenotypewiththesurroundings.Asaresult,manyfeaturesofanorganism'sphenotypearenothereditary.Forinstance,suntannedskincomesfromtheinteractionbetweenanindividual'sphenotypeandsunlightthus,suntansarenotpassedontotheiroffspring.However,someindividualstanmoreeasilythanothers,duetodifferencesintheirgenotype.Astrikingexampleisindividualswiththeinheritedcharacteristicofalbinism,whodonottanatallandarehighlysensitivetosunburn.Heritablecharactersarewell-knowntobepassedfromonegenerationtothenextwiththehelpofDNA,amoleculethatencodesgeneticinformation.DNAisalongpolymerthatincludesfourtypesofbases,whichareexchangeable.ThesequenceofbasesalongaspecificDNAmoleculestatesthatthegeneticinformation:thisiscomparabletoaseriesoflettersspellingoutapassageoftext.Beforeacelldividesviamitosis,theDNAiscopied,sothateachoftheresultingtwocellswillgettheDNAsequence.ApartofaDNAmoleculethatspecifiesasinglefunctionalunitisknownasgenedifferentgeneshaveadifferentseriesofbases.Withincells,thelongstrandsofDNAformcondensedstructuresso-calledchromosomes.Organismsgetgeneticmaterialfromtheirmotherandfatherintheformofhomologouschromosomes,havingauniquecombinationofDNAsequencesthatcodeforgenes.TheexactlocationofaDNAsequencewithinachromosomeiscalledalocus.Thedifferentformsofthissequencearecalledalleles.DNAsequencescanchangethroughmutations,makingnewalleles.Ifamutationtakesplacewithinagene,thenewallelecanaffectthecharacteristicthatthegeneregulates,alteringthephenotypeoftheorganism`NaturalSelectionNaturalselectionmakesachangeinthefrequencyofthegenesfromonegenerationtotheotherselectingthedifferentialtypeofthereproduction.Thenaturalselectionmethodformsanadaptiverelationbetweentheenvironmentandthepopulationoverseveralcombinationsofgenes.In1859,CharlesDarwinsetouthisphilosophyofevolutionbynaturalselectionasadescriptionofadaptationandspeciation.Hewell-definednaturalselectionasthe"principlebywhichevenaslightvariationoftrait,ifuseful,isconserved".Theideawassimplebutpowerful:personsbestadaptedtotheirsurroundingsaremorelikelytoliveandreproduce.Aslongasthereissomedifferencebetweenthemandthatdifferenceisheritable,therewillbeacertainselectionofindividualswiththemosthelpfulvariations.Ifthedifferencesaregenetic,thenadegreeofdifferencereproductiveachievementwillleadtoaprogressiveevolutionofspecificpopulationsofaspecies,andpopulationsthatgrowtobesufficientlydifferentfinallybecomedifferentspeciesBasedonthesesimpleremarks,Darwinconcludedthefollowing: Inapopulation,someindividualswillhavegenetictraitsthathelpthemliveandreproduce(giventheconditionsoftheenvironment,suchasthepredatorsandfoodsourcespresent).Theindividualswithhelpfulcharacterswillleavemoreoffspringinthenextgenerationthantheirpeerssincethecharactersmakethemmoreeffectiveatsurvivingandreproducing.Becausethehelpfulcharactersaretransmissible,andbecauseorganismswiththesetraitsleavemoreoffspring,thecharacterswilltendtobecomemorecommon(presentinalargerfractionofthepopulation)inthecominggeneration.Darwin'smodelofevolutionbynaturalselectionpermittedhimtoclarifythepatternshehadseenduringhisjourneys.Forexample,iftheGalápagosclasssharedacommonancestor,itmadesensethattheyshouldresembleoneanother.Ifgroupsofbirdshadbeenisolatedonotherislandsforseveralgenerations,still,everygroupwouldhavebeenvisibletoadifferentenvironmentinwhichdifferenttransmissiblecharacterscanbepreferred,likedifferentshapeandsizeofmouthsforusingdifferentfoodsources.Thesecharacteristicscouldhaveledtothedevelopmentofdistinctspeciesoneachisland. IsolationItisoneofthevitalaspectsresponsibleforthesynthetictheoryofevolution.Theisolationhelpsinavoidingtheinterbreedingoforganismswhichisagenerativeformofisolation.TypesofIsolationGeographicalIsolationWhenthepopulationsareseparatedbyageographicalbarrier,suchassea,river,mountain,desertsandformarineanimal’sland,theyarelargelyprohibitedfrominterbreeding.Suchpopulationsarecalledallopatricandareforcedtoevolvefreelyandaccumulategeneticdifferences.Geographicalisolationcanbedifferentfordifferentspecies.Forinstance,asmallstreammightbeaneffectivehurdleforlandinsectsandsmallmammalsbutforbirdsevenmountainsandoceansmaynotbebarriers.ReproductiveIsolationThemechanismsofreproductiveisolationareagroupofevolutionarymechanisms,behaviorsandphysiologicalprocessescriticalforspeciation.Theystopmembersofdifferentspeciesfromproducingoffspring,orguaranteethatanyoffspringaresterile.ThesehurdlesmaintaintheintegrityofaspeciesbyreducinggeneflowbetweenrelatedspeciesTemporalorHabitatIsolationAnyofthefactorsthatstoppotentiallyfertilebeingsfrommeetingwillreproductivelyisolatetheassociatesofdistinctspecies.Thekindsofhurdlesthatcancausethisisolationcontain:differenthabitats,physicalhurdles,andadifferenceinthetimeofsexualmaturityorfloweringBehavioralIsolationThedifferentmatingritualsofanimalspeciesgeneratetremendouslypowerfulreproductiveblocks,termedbehaviorisolation,thatisolateapparentlysimilartothespeciesinthemajorityofthegroupsoftheanimalkingdom.Indioeciousspecies,malesandfemalesrequiretosearchforapartner,beinvicinitytoeachother,carryoutthematingritualsandreleasetheirgametesintotheenvironmentinordertobreedMechanicalIsolationMatingpairscannotbeabletopairsuccessfullyiftheirgenitalsarenotcompatible.Insects'rigidcoveringsactinamanneranalogoustoalockandkey,astheywillonlyletmatingbetweenindividualswithmatchingstructures,thatis,malesandfemalesoftheidenticalspecies.Alltheabovepointsexplainthemodernsynthetictheoryofevolution.Wanttoreadoffline?downloadfullPDFhereDownloadfullPDFIsthispagehelpful?FAQsonModernSyntheticTheoryofEvolution1.Whatisthemodernsynthetictheoryofevolution?TheModernSyntheticTheoryofEvolutiontheoryisamodifiedformofDarwin’stheoryofNaturalSelection.ItisknownasNeo-Darwinism.Neo-DarwinismtheoryisthesynthesisofDarwin’stheoryandmoderngenetics.ThisModernSyntheticTheoryofEvolutionstatesthatthevariationswhichhappenatthegenelevelareonlyinherited(mutation)andaccountableforevolutionandnotallthevariationasheldbyDarwin.ThemodernconceptofevolutionisthesynthesisofDarwin’sandHugodeVries’Theories,henceitiscalledModernSyntheticTheoryofEvolution.2.WhichfactorsdoaffecttheModernSyntheticTheoryofEvolution?TheModernSyntheticTheoryofEvolution(alsocalledModernSynthesis)consolidatestheideaofDarwiniandevelopmentwithMendelianhereditaryqualities.ThefollowingaresomeofthefactorsthataffecttheModernSyntheticTheoryofEvolution.Thesefactorsare:NaturalselectionGeneMutationChromosomestructureandnumberchangeGeneRecombinationNaturalselectionReproductiveisolationMigrationHybridizationGeneticdriftGeneflowRelatedarticlesDifferenceBetweenHypothesisAndTheoryBiology•Class12DifferenceBetweenNaturalSelectionandAdaptationBiology•Class12SexualSelectionBiology•Class12TypesofSelectionsinScientificEvolutionTheoryBiology•Class12DifferenceBetweenDarwinismandNeoDarwinismBiology•Class12RecentlyUpdatedPagesAeroponics-Structure,Function,AdvantagesandDisadvantagesViewpageTestCross-DefinitionandExamplesViewpageMustard:ScientificNameofMustard,ClassificationandEconomicImportanceViewpageUreaCycle-Steps,SignificanceandImportanceViewpageTheCat-Types,Taxonomy,BreedsandFactsViewpageHypotonicSolution-Overview,Introduction,SolutionandExamplesViewpageRecentlyUpdatedPagesAeroponics-Structure,Function,AdvantagesandDisadvantagesViewpageTestCross-DefinitionandExamplesViewpageMustard:ScientificNameofMustard,ClassificationandEconomicImportanceViewpageUreaCycle-Steps,SignificanceandImportanceViewpageTheCat-Types,Taxonomy,BreedsandFactsViewpageHypotonicSolution-Overview,Introduction,SolutionandExamplesViewpageLearnthroughvideosClass12passClass12Class11Class10Class9Class8Class7Class6Class1-5LKG-UKGMoreforclass10NCERTSolutionsRevisionNotesSamplequestionpapersNCERTBooksTrendingpagesPermanentTissueViewpageNucleus-WhatisNucleusViewpageSenseOrgansViewpageBinomialNomenclatureViewpageLivingandNon-LivingThingsViewpageFoodSourceViewpageDifferenceBetweenRabiandKharifCropsViewpageDoubleCirculationViewpageComponentsofFoodViewpageStudymaterialsLiveclassesExploreSyllabusExplore