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CLASS4-16March:GENE

1. Historyoftheconcept2. Geneasinformation3. Genesanddevelopment4. Genesandevolution

Bibliography:sentorcited

FORMATERIAL,SENDEMAILTO:[email protected]

Enrolment:GabinetedeEstudosPos-graduados 1

mailto:[email protected]

1.1Prehistory

Onlyinthenineteenthcenturyhereditybecameamajorproblemtobedealtwithinbiology:why?

Whatwasknownfrombreedingexperimentsisthatthereweretwokindsofvariations:fluctuating/quantitativechanges(deviationfromnormaltrait)anddiscontinuous/qualitativeones(appearanceofqualitativelynewtraits).Alltherestwasamatterofdebate(cytologyorcellbiologywasdeveloping).

Twomainsetsofproblems1. Natureoftheunitsofheredity:localisationinthebody;material

constitution(whatkindofstuffandwhatkindofstructure);2. Mechanismoftransmissionfromonegenerationtotheother. 2

1.2Pre-history:transmissionview

Natureoftheunitsofheredity:localisationinthebody;materialconstitution(whatkindofstuffandwhatkindofstructure);

“BIOLOGYhasevidentlyborrowedtheterms‘heredity’and‘inheritance’fromeverydaylanguage,inwhichthemeaningofthesewordsisthe‘transmission’ofmoneyorthings,rightsorduties—orevenideasandknowledge…Hippocrates….suggestedthatthedifferentpartsofthebodymayproducesubstanceswhichjoininthesexualorgans,wherereproductivematterisformed.Darwin’shypothesisof‘pangenesis’isinthispointveryconsistentwiththeHippocraticview…AlsotheLamarckianviewastotheheredityof‘acquiredcharacters’isinaccordancewiththoseoldconceptions.”JohannsenW.TheGenotypeConceptionofHeredity.TheAmericanNaturalist1911;45:129-159.p.989

WhatisJohannsensuggestingasanalternativeview?3

1.3Pre-history:Darwin’spangenesis


Pangenesis

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1.4Pre-history:Darwin’spangenesis


ReactiontoDarwin’spangenesishypothesis:

-FrancisGalton:gemmulesarenotcirculatingthroughbloodstream(experimentswith88rabbitswith“noalterationofbreed”asaresult);-DeVries:unitsofhereditystayinthecells;-AugustWeismann:transmissionfromsomatictissuetogerminaltissuedoesnothappen;

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1.5Prehistory:whatkindofstuff


-HerbertSpencer:unitsofheredityareentitieswithadimensionbetweenmoleculesandcells;-AugustWeismann:localisationinthenucleusofthecell,specificallyinthechromosomes;chromatinparticlesarebearersofspecialorganisingfunctionsindevelopment:

-RediscoveryofGregorMendel’swork

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1.6Prehistory:Mendelism

Mendel:

FavouritetheoryofinheritanceatthetimeofMendel:blendinginheritance(vsparticulate;i.e.,theideathatcharactersfromparentsareinheritedinamixedformbyoffspring;theproblemofthisviewwashowtoexplaintheappearanceofqualitativelynewvariantsnotpresentinpreviousgenerations)+inheritanceofacquiredtraits(e.g.,transmissionmodelofinheritance:personalqualitiesofindividualorganismcausethequalitiesofitsoffspring).

Peaplantshavemanydichotomoustraits(notcompatiblewithblendinginheritance).

Startwithtruebreedinglines(whicharegeneticallypureormonistic,withjustonetypeofallelepertrait);createmono-hybridcrossbycross-fertilisingtwogardenpeaplantswithdichotomoustraitsandseewhathappens. 7


ParentalGeneration:Purple&WhiteflowersFilialGeneration1:PPPP(disappearanceoftrait….explainedbydominance)FilialGeneration2:PPPW(reappearanceinthesameproportion…explainedbyreappearanceofrecessivetrait)

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Mendel:

Homozygous(2allelesofthesametype)vsheterozygousorganisms;

PP–purpleG/PmapPp–purpleG/Pmappp–whiteG/Pmap

1TO2TO1RATIO

LAWOFSEGREGATION:allelepairsseparateduringgameteformation,andrandomlyuniteatfertilisation.

LAWOFINDEPENDENTASSORTMENT:individualhereditaryfactorsassortindependentlyduringgameteproduction,givingdifferenttraitsanequalopportunityofoccurringinnextgeneration.

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RediscoveryofMendel’sworkin1900byHugodeVries,CarlCorrens,andErichTschermak.Newparadigmofinheritance:

1.Heritablefactor(differentversionsofthegene,e.g.,allele)responsibleforappearanceoftrait;2.Indiploidorganisms(i.e.,havingtwohomologouschromosomesineachcell)thereare2alleles/particles/heritablefactorsforeachtrait;3.Oneallelecouldbedominantandtheotherrecessive;4.Whengametesareformedbyparentsinpreparationforsexualreproduction,thegametesgetonlyoneofthetwoforms;hence50%chance;5.Allelesaretheheritablefactors,notthepersonalqualities(i.e.,themorphological,physiologicalandbehaviouralmanifestationsoftheheritablefactors,thatis,thephenotypes)oforganisms;6.Allelesareparticulate,discreteobjects(vsblendinginheritance). 10

1.10Pre-history:genotypeconception

“Thepersonalqualitiesofanyindividualorganismdonotatallcausethequalitiesofitsoffspring;butthequalitiesofbothancestoranddescendantareinquitethesamemannerdeterminedbythenatureofthe‘sexualsubstances’—i.e.,thegametes—fromwhichtheyhavedeveloped.Personalqualitiesarethenthereactionsofthegametesjoiningtoformazygote;butthenatureofthegametesisnotdeterminedbythepersonalqualitiesoftheparentsorancestorsinquestion.Thisisthemodernviewofheredity.”

Genotypeconceptionofheredity:“…Ihaveproposedtheterms“gene”and“genotype”andsomefurtherterms,as“phenotype”…tobeusedinthescienceofgenetics.The“gene”isnothingbutaveryapplicablelittleword,easilycombinedwithothers,andhenceitmaybeusefulasanexpressionforthe“unit-factors,”“elements”or“allelomorphs”inthegametes,demonstratedbymodernMendelianresearches.A“genotype”isthesumtotalofallthe“genes”inagameteorinazygote.…….phenotypesarerealthings…”

JohannsenW.TheGenotypeConceptionofHeredity.TheAmericanNaturalist1911;45:129-159.pp.990+991 11

1.11Genotypeconception:issues

Twomainsetsofproblems:Natureoftheunitsofheredity:localisationinthebody;materialconstitution(whatkindofstuffandwhatkindofstructure);Mechanismoftransmissionfromonegenerationtotheother.

3basicdistinctionsconcerningnatureofgenes:1. germvssoma(Weismann);2. discretevscontinuousgeneticfactors(Mendel);3. genesvsphenotypes(Johannsen).

Pendingissues:• Localizationinthecell;• Mechanismofinheritance;• Deploymentindevelopment.

“Astothenatureofthe‘genes’itisasyetofnovaluetoproposeanyhypothesis;butthatthenotion“gene”coversarealityisevidentfromMendelism….”JohannsenW.TheGenotypeConceptionofHeredity.TheAmericanNaturalist1911;45:129-159.pp.990+991 12

2.1Fromtheoreticalentitiestomaterialones

ThomasHuntMorganandthefruitflyDrosophilamelanogastergroup.

Geneslocatedinalinearorderalongthedifferentchromosomes(like"beadsonastring”,Morgan,T.H.,1926.Thetheoryofthegene,NewHaven:YaleUniversityPress.p.24)

Morgan’sprogrammewasformal,thusagnosticconcerningmaterialnatureofgenesandcomplexityofG-Pmap(i.e.,the“genotype-phenotypemap”;seeRheinberger,Müller-WilleandMeuniersection2).

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Interlude:thegenotype-phenotypemapasabijecsvefuncson—>everygenecausesonephenotypeindevelopment

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1.samegenotypeassociatedwithseveralphenotypes(i.e.,pleiotropy,forinstancerepresentedbyG1influencingdevelopmentofP1,P2,andP3);2.severalgenotypesassociatedwiththesamephenotype(i.e.,polygeniccontrolofdevelopment,representedbyP2beinginfluencedbyG1,G2andG3);3.samegenotypeassociatedwithdifferentphenotypesindifferentenvironments(aformofenvironmentalcontrolofgeneexpression,representedbyG1influencingdevelopmentofP1inenvironmentE1andP4inenvironmentE2);4.differentgenotypesinthesameenvironmentproducingsamephenotype(aformof“environmentaldeterminason”ofphenotype,representedbyG2andG3influencingdevelopmentofP3inenvironmentE3)

Interlude:thegenotype-phenotypemapasacomplexfuncson

2.2Fromtheoreticalentitiestomaterialones

Aimofclassicalgenetics:findingaformalcorrelationbetweenindividualgenes(characterisedasspecificlocionthechromosomes)withcertaincharacters.

Veryimportantfordevelopmentofmathematicalpopulationgenetics:“…RonaldA.Fisher,J.B.S.Haldane,andSewallWrightcouldmakeuseoftheclassicalgenewithequalrigorandprecisiontoelaboratetestablemathematicalmodelsdescribingtheeffectsofevolutionaryfactorslikeselectionandmutationonthegeneticcompositionofpopulations(Provine1971).Asaconsequence,evolutionbecamere-definedasachangeofgenefrequenciesinthegenepoolofapopulation…“(seeRheinberger,Müller-WilleandMeuniersection2). 16

2.3Genesinpopulationgenetics

“ScottGilbert(2000)hassingledoutsixaspectsofthenotionofthegeneasithadbeenusedinpopulationgeneticsuptothemodernevolutionarysynthesis.First,itwasanabstraction,anentitythathadtofulfillformalrequirements,butthatdidnotneedtobeandindeedwasnotmateriallyspecified.Second,theevolutionarygenehadtoresultinorhadtobecorrelatedwithsomephenotypicdifferencethatcouldbe“seen”ortargetedbyselection.Third,andbythesametoken,thegeneoftheevolutionarysynthesiswastheentitythatwasultimatelyresponsibleforselectiontooccurandlastacrossgenerations.Fourth,thegeneoftheevolutionarysynthesiswaslargelyequatedwithwhatmolecularbiologistscametocall“structuralgenes.”Fifth,itwasageneexpressedinanorganismcompetingforreproductiveadvantage.Andfinally,itwasseenasalargelyindependentunit.”(seeRheinberger,Müller-WilleandMeuniersection4) 17

2.4Genesasautocatalyticandheterocatalytic

HermanJ.Muller:genesasmaterialparticles:

“Mullersawgenesasfundamentallyendowedwithtwoproperties:thatofautocatalysisandthatofheterocatalysis.Theirautocatalyticfunctionallowedthemtoreproduceasunitsoftransmissionandthustoconnectthegenotypeofonegenerationtothatofthenext.Theirconcomitantcapabilityofreproducingmutationsfaithfullyoncetheyhadoccurredgaverise,onthisaccount,tothepossibilityofevolution.Theirheterocatalyticcapabilitiesconnectedthemtothephenotype,asunitsoffunctioninvolvedintheexpressionofaparticularcharacter.Withhisownexperimentalwork,Mulleraddedasignificantargumentforthematerialityofthegene,pertainingtothethirdaspectofthegeneasaunitofmutation.In1927,hereportedontheinductionofMendelianmutationsinDrosophilabyusingX-rays.”(Rheinberger,Müller-WilleandMeuniersection2). 18

2.5Geneasautocatalyticentities

Muller:genesasautocatalyticentitiesableofself-replicationthusexplainingthemechanismofinheritance.

GenesareDNAmolecules,notproteins:OswaldAvery,ColinMacLeod,andMaclynMcCarty1944

DNAstructureasadoublehelix:FrancisCrickandJamesD.Watson1953

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FrederickGriffith’sexperiment(1928):

TypeII-R(nonvirulent)strainsofbacteria—>nodeadmice

TypeIII-S(virulent)strain—>deadmice

KillbyheatbacteriaoftypeIII-Sstrain—>nodeadmice

Mixheat-killedtypeIII-SstrainwithtypeII-Rstrain—>deadmice

WhatmolecularagentisresponsibleforTRANSFORMATIONoftypeII-R(nonvirulent)strainbacteriaintotypeIII-S(virulent)ones?Proteinsorsomeothermolecularagent?

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Averyetal.experiment1944

OnlyintheculturetreatedwithDNasedidtheSstrainbacteriafailtogrow;noDNA=notransformason—>genes=DNAstuff

cf.hzps://ib.bioninja.com.au/higher-level/topic-7-nucleic-acids/71-dna-structure-and-replic/dna-experiments.html

https://ib.bioninja.com.au/higher-level/topic-7-nucleic-acids/71-dna-structure-and-replic/dna-experiments.html


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DNAasgeneticmaterial:butwhataboutitsstructure?DNAasdoublehelix:FrancisCrickandJamesD.Watson1953(slide2.8).

Andhowcanithaveautocatalyticproperties?MatthewMeselsonandFranklinStahlin1958:DNAreplicatessemi-conservatively(cf.https://www.nature.com/scitable/content/the-meselson-stahl-experiment-18551/). 23

https://www.nature.com/scitable/content/the-meselson-stahl-experiment-18551/


Muller:genesasautocatalyticentitiesableofself-replicationthusexplainingthemechanismofinheritance.

GenesareDNAmolecules,notproteins:OswaldAvery,ColinMacLeod,andMaclynMcCarty1944

DNAasdoublehelix:FrancisCrickandJamesD.Watson1953

DNAreplicatingsemi-conservatively:MeselsonandStahl1958

“…thestructureoftheDNAdoublehelixhadallthecharacteristicsthatweretobeexpectedfromamoleculeservingasanautocatalytichereditaryentity…“(Rheinberger,Müller-WilleandMeuniersection3).

Butaregenestrulyself-replicating? 24

3.1Themoleculargeneanddevelopment

Genesasheterocatalyticentities(slide2.4)causallyassociatedwithparticularphenotypes:-onetoonemapping(Morgan’sschool);-onegenexforoneenzyme(GeorgeBeadleandEdwardTatum);-genesareinformationalunitsthatdeterminedevelopmentaloutcomes.

WatsonandCrickpopularisedinformationtalkingenetics.TheyhypothesisedthatgenesmightbeencodedintheDNAmolecule,morepreciselyinthenucleotides:

“…inalongmolecule,manydifferentpermutationsarepossible,anditthereforeseemslikelythattheprecisesequenceofthebasesisthecodewhichcarriesthegeneticalinformation.”(Watson,J.D.&Crick,F.H.(1953).MolecularStructureofNucleicAcids:astructurefordeoxyribosenucleicacid.Nature,171(4356):737–738.,p.964)

Sequencehypothesis:“…thesequenceofbasesdeterminesthesequenceofaminoacidsoftheproteinbeingsynthesized”.(Crick,F.(1958)OnProteinSynthesis.TheSymposiaoftheSocietyforExperimentalBiology,12,138-163.,p.158)

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3.2Themoleculargeneasinformation

Theontologicalfoundationoftheinformationalinterpretationisadoublereification:

1. ofgeneticinformationasanon-physicalentity;

2. ofinformationalspecificityasanon-physicalformofspecificity.

Williams(1966)proposedacyberneticconceptionofthegenethatmakesitindependentofitsmolecularsubstrate:

“AgeneisnotaDNAmolecule;itisthetranscribableinformationcodedbyamolecule....thegeneisapacketofinformation,notanobject.”(Williams,G.C.(1992).NaturalSelection:Domains,Levels,andChallenges.OxfordUniversityPress,p.11)

“...heredityisconcernedwiththetransmissionofinformation,notjustofmatterorenergy.”(J.Maynard-Smith2001.Theconceptofinformationinbiology.PhilosophyofScience,67:177-194p.182)


“If[eyeless]isactivatedinadevelopingleg,thenaneyedevelopsatthesite....Thissuggeststhatthegeneissendingasignal,'makeaneyehere'...”

J.Maynard-Smith2001p.188

InductionofectopiceyestructuresinDrosophila.


Theontologicalfoundationoftheinformationalinterpretationisadoublereification:

1. ofgeneticinformationasanon-physicalentity(Williams1966,1992).

2. ofinformationalspecificityasanon-physicalformofspecificity;

Informationalspecificityisontologicallydifferentfrombiochemicalspecificity.Crick’sinformationalspecificitywasreifiedasapeculiarkindofrelationshipbetweenDNAsequenceanddevelopmentaloutcome:

“Thespecificityofthegene-geneproduct(nucleicacidorprotein)relationshipwasinformationalandthusdifferentfromspecificityateveryotherlevelofbiologicalorganization,whichremainedphysical(orstereospecific).”(Sarkar2005,p.367)


Conformasonalcomplementarityofenzymesandsubstrateisaphysicalrelasonship,butthatofDNAwithitsgene-products(RNAtranscriptsandproteins)ispurely

informasonal.Whatdoesthismean?

3.6Molecularbiologyvsinformationtalk

Maindrawbackisthecreationoftwosuspiciousasymmetries:

1. betweenprocessesliketranscription,translationandproteinfoldingthatcanberepresentedininformationaltermsontheonehand,andallotherdevelopmentalprocessesnotamenabletoastraightforwardinformationalrepresentation;

2. betweentheputativecausalroleofDNAandextragenomicdevelopmentalresourcesindevelopment.

Thefirstasymmetryisunjustifiedbecauseprocessesliketranscription,translationandproteinfoldingturnedouttobeextremelycomplexbiochemicalprocesses,nodifferentinkindfromallotherdevelopmentalones.

Knowledgeabouteukaryotictranslationrevolutionisedbythediscoveryofalternativesplicingin1977:

“Inthecaseoftheegg-layinghormoneofAplysia,totakejustoneexample,oneandthesamestretchofDNAgivesrisetoelevenproteinproductsinvolvedinthereproductivebehaviorofthissnail.”(Rheinberger,Müller-WilleandMeuniersection3)

Proteinfolding(basedonAnfinsen’s“dogma”:theprimarystructureoftheproteinisdeterminedbytheprotein'saminoacidsequence):discoveryoftheroleofchaperonesandfoldingcatalyistsintheprocess.

3.7Proteinbiosynthesis

3.9Contrivancesofprokaryosctranscripson

4.1DNA’scausalroleindevelopment

Maindrawbackisthecreationoftwosuspiciousasymmetries:

1.betweenprocessesliketranscription,translationandproteinfoldingthatcanberepresentedininformationaltermsontheonehand,andallotherdevelopmentalprocessesnotamenabletoastraightforwardinformationalrepresentation;

2.betweentheputativecausalroleofDNAandextragenomicdevelopmentalresourcesindevelopment.

Genesdeterminephenotypicoutcomes(seealsoclass3ondevelopment).

Genespossessaqualitativelydifferentkindofspecificity.

4.2Dogenesdeterminephenotypicoutcomes?

ConradHalWaddingtonproposedaninterpretationofgeneactionthatwasdeterministicdespitethewell-knowncomplexityofthegenotype-environmentrelationship(rememberWoltereck’sexperimentswithdaphniain1909,slide3.10class2).

“…thefactorwhich,inthedevelopmentofvertebrates,decideswhichofthealternativemodesofdevelopmentshallbefollowedistheorganiser,or,morespecifically,theactivechemicalsubstanceoftheorganiserwhichhasbeencalledtheevocator.”(Waddington1939,p.S37)

Theevocator(amolecularagent)playsthecausalroleindevelopmentalprocessesby“deciding”whichdevelopmentalpathistaken.


RememberWaddington’sepigeneticlandscape(slide3.4class2):

1. developmentisaprocessthatcanberepresentedasconsistingofmanydiscretestepsorbifurcationswithnointermediatesbetweenthem;

2. evocators“decide”whichpathistakenbythedevelopingorganismateverybifurcation;

3. inthissense,evocatorsaredeterminantsofdevelopment.


Waddington’sinference:genesidentifiedwithevocators:

“…genes...actinawayformallylike...evocators,inthattheycontrolthechoiceofalternative.”(Waddington1939,p.S37)

Developmentalbiologybecomesthereforetheprovinceofdevelopmentalgenetics.

AsWaddingtonclaimedlater:

“…weknowthatgenesdeterminethespecificnatureofmanychemicalsubstances,celltypes,andorganconfigurations;andwehaveeveryreasontobelievethattheyultimatelycontrolallofthem.”(Waddington1962,p.4)

TheideathatDNAisadevelopmentaldeterminantfinallyfounditsconceptualunderpinning.

(Cf.Sarkar2005+Vecchi2019).

4.5Theswitch-pointmodelofdevelopment

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4.6Genetic“determination”

Giventhattherecannotbeentiredevelopmentaltrajectoriesthataretotallygeneticallyorenvironmentallydetermined,theuseofthelanguageofdeterminationismisleading(West-Eberhard,2003,p.99-100).Thisissufficienttodispelthetraditionalideaofgeneticdetermination(i.e.,thatanadultphenotypeisfullydeterminedbygenomicinputs;cf.genexforphenotypePidea).

Butisthedevelopmentaloutcomebesidescompatiblewiththismodel?

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4.7Developmentalstructuralism

Sometimesgenesseemtodeterminedevelopmentaloutcomes.However,thisviewisnotincompatiblewithotherdevelopmentalapproachesthatconsidergenesassecondary,andsometimesirrelevantindevelopment.

Developmentalstructuralismisonesuchapproach:

“Byfocusingontheelasticandviscousfeaturesofthecytoskeleton,andneglectingtheextremelysmallaccelerations,theseauthorssucceededinprovingthatthecontractionofasinglecellpropagatestotheadjacentcellsandgeneratesaninvaginationintheepithelium.Suchmodelsarephilosophicallyinteresting…becausetheyhelptodispensewithpreformationistmyths:"[...]oncetriggered,themorphogeneticprocessofinvaginationproceedsonitsown,directedsolelybytheglobalbalanceofmechanicalforcesgeneratedlocallybyeachcell,andwithnorequirementforindividuallypreprogrammedsequencesofpatternsofcellshapechange"(Odelletal.1981,p.450).MahnerandBungep.298

4.8Developmentalconstructivism

Developmentalconstructivismendorsesthe“causalparity”thesis:

“….nocausalordeterminativepriorityindevelopmentcanbeassignedeithertothegenes,i.e.,tointernalfactors,ortotheenvironment,i.e.,toexternalfactors.Itisemphasizedthat"phenotypes"arenottransmittedfromonegenerationtothenext,e.g.,incodedforminthegeneticmaterial,butthattheyareconstructedanewineachgenerationthroughorganism-environmentinteractionsduringdevelopment.”MahnerandBungep.299

“Theconstructionistviewofdevelopmentalsocallsforanexpandednotionofinheritance(Oyama1985).Ifphenotypictraitsarenotinanywaytransmittedbutconstructedanewduringdevelopment,thenthequestionariseswhat,ifanything,doorganismsinherit.Ofcourse,organismsinheritgenes,buttheyalsoinheritcytoplasmicfactors(actuallytheentireinitialorganizationofthecell)and,afterall,acertainenvironment(Gray1992).”MahnerandBungep.300

Epigeneticinheritance

4.9Dogenespossessaqualitativelydifferentkindofspecificity?

TheargumentisfrequentlymadethatDNAisahighlyspecificdevelopmentalcause.

But,aspecificphenotypicchangecanbeproducedeitherthroughamutationorthroughachangeintheconcentrationofageneproductcausedbyenvironmentalfactors.Thesetwokindsofchangesarebiochemicallyequivalent(ZuckerkandlandVillet1988).

4.10DNAasapeculiarresource

ContemporarygenomicsandmolecularbiologymakeclearthatknowledgeofDNAsequenceisinsufficienttopredictaccuratelyproteinstructureand–evenmoreso-anyhigherlevelphenotypicoutcome(eventhoughexceptionsexist,e.g.,eyelessgene).

DNAisadevelopmentalresource,notadeterminant(Sarkar2005).

Givenallthis,canwestilldefendtheideathatDNAhasacentralroleindevelopment?Orshouldtheso-called“paritythesis”beendorsed?

Backin1926,HermannJosephMullerexplainedthecentralityofgenesinthismanner:

"…inallprobabilityallspecific,generic,andphyleticdifferences,ofeveryorder,betweenthehighestandlowestorganisms,themostdiversemetaphytaandmetazoa,areultimatelyreferabletochangesin...genes.”(Muller1962,p.195)

Thepeculiarityofthisclaimliesinthefactthatitwasmadein1926.Backthen,nobodyknewwhatgenesaremadeofandnobodyhadaclueabouthowcontrivedtherelationshipbetweengenesandphenotypeis.ButMullerwashypothesizingthatphenotypiccomplexityisdependentongeneticcomplexity.Washeright?

4.11DNAasapeculiarresource

Summingup

Thecomplexhistoryofgeneticsispavedwithmanyexperimentalandtheoreticaladvances:fromtheemergenceoftheMendelianparadigmofinheritancetothegenotype-conceptionofheredity,fromthemolecularizationofthegenetotheadvancesofcomparativegenomics.

Theclaimthatgenesareinformationismetaphorical:thecausalroleofgenescannotbeuncoveredwithoutabiochemicalunderstandingofgeneexpression.

Genesarenotdevelopmentaldeterminantsbuttheyarehighlyspecificcausesnotonaparwithotherdevelopmentalones.

Thecausalroleofgenesinevolutionhasyettobeunderstood:ifphenome(i.e.,thesetofphenolypesanorganismcanmanifest)complexitydependsongenome(i.e.,thesetofgenomicresourcesanorganismpossesses)complexity,thengenesarecentralinevolution.

Toclaimthatgene-basedmodelsofdevelopmentandevolutionmighteventuallydisappearbecausethegenemightnotturnouttobeaprimitiveontologicalcategoryofbiology(endofRheinberger,Müller-WilleandMeunieressay)isinmypersonalopinionaveryquestionableconclusion.

CLASS5-23March:EVOLUTION1.Vecchi,D.(2018).Biodiversiade:Oqueéeporqueéimportante.Chapter2.(IwillsendalsotheEnglishversion)

2.Sober:chapter1

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