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FOSSILSandFOSSILIZATION part2–TaxonomyandLifeForms:ArchaeaandBacteria AlessandroGrippo,Ph.D. Dinosaurfootprint,StGeorgeDiscoveryCenter,StGeorge,Utah ©AlessandroGrippo TaxonomicGroups • Taxonomy – ThestudyofthecomposiAonof,andrelaAonship betweendifferentgroupsoforganisms – Inotherwords,taxonomydealswithwhatbelongsto agroup(ortaxon)andhowtaxonomicgroupsare relatedtoeachother • Taxonomicgroups,ortaxa – Alllifeformsbelongtodifferentcategories,or taxonomicgroups,basedontheircharacterisAcs LifeonEarthisdividedinthreeDomains • Archaea – Prokaryotes • Bacteria – Prokaryotes • Eukarya – Eukaryotes • AlllifeformsareformedbycellscontainingDNA • ProkaryoAccellslackinternalorganizaAon • EukaryoAccellspresentinternalstructuring Taxavs.Clades • Domainsaredividedinsmallergroupings,orclades • Whatisthedifferencebetweenataxonandaclade? – Ataxonisanygroupofspecies – AcladeisamonophyleActaxon,thatisataxonthat containsonlyalldescendantsofacommonshared ancestorandthecommonancestor OnlyTaxon1isaClade Taxonomy • AllProkaryotes(ArchaeaandBacteria)are unicellular • SomeEukaryotesareunicellular,othersare (likeus)pluricellular • Alltaxaareorganizedinahierarchy,from DomaintoSpecies TaxonomicHierarchy • TheDomainisthehighest-ranktaxon(or taxonomicgroup) – WithinaDomainistheKingdom – WithinaKingdomisthePhylum,andsoon: – WithinaPhylumistheClass,followedbytheOrder, theFamily,theGenusand,last,theSpecies. • ASpeciesisagroupofindividualsthatcan interbreed AnexampleofTaxonomicHierarchy • Theseareallthetaxonomicgroupsamountainlionwouldbelongto: • NamesofTaxaarecapitalized,exceptforSpecies • GenusandSpeciesareitalicized • Thenameofthespeciesisalwaysassociatedwiththatofthegenus – Felisconcolor – Homosapiens theTreeofLife • evidenceformmorphology,biochemistryandgene sequencingstronglysuggeststhat ALLEARTHORGANISMSAREGENETICALLYRELATED • ThegenealogicalrelaAonshipsbetweenalllivingthings canberepresentedbytheTreeofLife • TheTreeofLiferepresentsthePhylogenyoforganisms (thatis,thehistoryoftheirlineageastheychange throughAme) theTreeofLife DomainsArchaeaandBacteria • CollecAvelyknownas“bacteria” • Prokaryotes • Unicellular • Mostlyverysmallinsize – between500nmand2µm – 1000nm=1µm;1000µm=1mm;1000mm=1m “bacteria”(ArchaeaandBacteria) • beingsosmall,bacteriahavenophysical spacewithintheircellstohostamore organizedstructure,typicalofEukaryotes • Simplicityofbacterialcellfavorsbasiclife processesandfuncAons • Easierforbacteriatothrivein“extreme” environments(precludedtouseukaryotes) ArchaeaandBacteria • Archaea(or Archaebacteria)can surviveinextreme environments • Bacteria(or Eubacteria,“True” bacteria)arepresent almosteverywhere, includingourbody Archaea:LifeinExtremeEnvironments • ExtremecondiAonsprevailedonEarthatthe verybeginningofitsexistence • Precambrianlifeisvirtuallyonlybacterial (eukaryotesshowupverylateduringthe Proterozoic) • Notmanyfossilsle`:studyofsignaturesle`in rocksbybacteria Archaea:LifeinExtremeEnvironments • Bacteriaestablishthebroadestlimitsforlife • BacteriacansurviveincondiAonswewould otherwisedefineas“impossible” Archaea:LifeinExtremeEnvironments – Temperature • hothydrothermalvents(mid-oceanridges) • hotspots(hotpoolsatYellowstoneNaAonalPark) • polarice(andiceingeneral) – Pressure • interstellarspace • deepoceantrenches • afewkilometersunderground Archaea:LifeinExtremeEnvironments – Waterchemistry • acidicwaters • alkalinewaters – ExtremedesiccaAon • waterbasinswithhighsalinity • dryenvironments,includingsaltpanslikeinDeathValley – RadioacAvity • somebacteriawouldsurvivesterilizingamountsofradiaAon • bacteriafoundwithinthewatercoreofnuclearreactors ExtremeEnvironments: fourexamplesfromourownCalifornia Alkalinewaters:MonoLake Saltwaterstosaltdeposits:DeathValley HotSpringswater:Bridgeport Iceandcoldwaters:ConvictLake Bacteria • Bacteriainclude: – decomposers – photosynthesizers – agentsofdisease – polluters Bacteria:cyanobacteria • PhotosyntheAcbacteria – someAmescalledbluealgaebecausetheymake photosynthesis(buttheyarenotalgae!) • Le`animportantfossilrecord(sincethePrecambrian) instromatolites • Somestromatolitesaredatedtomorethan3billion yearsago • Canbesphericalorfilamentous(threadlike) sphericalcyanobacteria filamentouscyanobacteria • Nostoc – TheseCyanobacterialiveinclusters withinagelaAnoussphere,usually ahachedtoasurface.Theindividual Cyanobacteriaarethesmall,filamentous cellsinsidethatformlongstrands.Some ofthecellsarelarger. • Anabaena – Planktonic,solitary fromCyanobacteriatoStromatolites • Somefilamentouscyanobacteriafloatas greenishscumonlake,streams,orocean waters • Othersform“algal”matsontheseafloorthat cantrapsedimenttoproducedisAncAve3-D structures(stromatolites) ModernStromatolitesfromSharkBay,Australia Stromatolites infour“simple”steps ① AccreUonaryorganosedimentarystructures thestructurebuildup(accretes),andformsastructurethroughinteracAonof biologicalandphysicalprocesses ② commonlythin-layered,megascopic,andcalcareous madeofthin,stackedlaminae,visibletothenakedeye,parAallycomposedof calciumcarbonateminerals ③ producedbytheacUvityofmat-buildingcommuniUesofmucilagesecreUngmicroorganisms microscopicorganismslivingtogethergeneratemats,orlayersbysecreAngsAcky gelaAn-likeslime ④ mainlyfilamentousphotoautotrophicprokaryotessuchas cyanobacteria mostorganismsaredevelopingthreads(andnotspheres),arephotosyntheAc,are BacteriaandArchaea,andmostoftheAmesarecyanobacteria Fossil Stromatolites fromGlacierNaAonalPark, Montana Fossils and FossilizaUon endofpart2
