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PAGE 1 WhatisBiodiversity CollectionEditor: NoraBynum PAGE 3 WhatisBiodiversity CollectionEditor: NoraBynum Authors: RobertAhlnger JamesGibbs IanHarrison MelinaLaverty EleanorSterling Online: < http://cnx.org/content/col10639/1.1/ > CONNEXIONS RiceUniversity,Houston,Texas PAGE 4 2008NoraBynum ThisselectionandarrangementofcontentislicensedundertheCreativeCommonsAttributionLicense: http://creativecommons.org/licenses/by/3.0/ PAGE 5 TableofContents 1GlobalProcesses ..................................................................................1 2DenitionofBiodiversity .........................................................................5 3SpatialGradientsinBiodiversity ................................................................7 4IntroductiontotheBiodiversityHierarchy .....................................................9 5WhatisBiodiversity?Acomparisonofspidercommunities .................................11 6SpeciesDiversity .................................................................................25 7Alpha,Beta,andGammaDiversity ............................................................31 8IntroductiontoUtilitarianValuationofBiodiversity .........................................33 9BiodiversityoverTime ..........................................................................35 10ABriefHistoryofLifeonEarth ..............................................................37 11EcosystemDiversity ............................................................................39 12PopulationDiversity ............................................................................41 13BiogeographicDiversity ........................................................................43 14CommunityDiversity ...........................................................................45 15Ecoregions .......................................................................................47 16Extinction .......................................................................................49 17LandscapeDiversity ............................................................................51 18EcologicalValue .................................................................................53 Glossary .............................................................................................55 Bibliography ........................................................................................59 Index ................................................................................................66 Attributions .........................................................................................67 PAGE 6 iv PAGE 7 Chapter1 GlobalProcesses 1 1.1AtmosphereandClimateRegulation Lifeonearthplaysacriticalroleinregulatingtheearth'sphysical,chemical,andgeologicalproperties,from inuencingthechemicalcompositionoftheatmospheretomodifyingclimate. About3.5billionyearsago,earlylifeformsprincipallycyanobacteriahelpedcreateanoxygenated atmospherethroughphotosynthesis,takingupcarbondioxidefromtheatmosphereandreleasingoxygen Schopf1983 [87]; VanValen1971 [104].Overtime,theseorganismsalteredthecompositionoftheatmosphere,increasingoxygenlevels,andpavedthewayfororganismsthatuseoxygenasanenergysource aerobicrespiration,forminganatmospheresimilartothatexistingtoday. Carboncyclesontheplanetbetweentheland,atmosphere,andoceansthroughacombinationofphysical, chemical,geological,andbiologicalprocesses IPCC2001 [73].Onekeywaybiodiversityinuencesthe compositionoftheearth'satmosphereisthroughitsroleincarboncyclingintheoceans,thelargestreservoir forcarbonontheplanet GruberandSarmiento [36],inpress.Inturn,theatmosphericcompositionof carboninuencesclimate.Phytoplanktonormicroscopicmarineplantsplayacentralroleinregulating atmosphericchemistrybytransformingcarbondioxideintoorganicmatterduringphotosynthesis.This carbon-ladenorganicmattersettleseitherdirectlyorindirectlyafterithasbeenconsumedinthedeep ocean,whereitstaysforcenturies,oreventhousandsofyears,actingasthemajorreservoirforcarbon ontheplanet.Inaddition,carbonalsoreachesthedeepoceanthroughanotherbiologicalprocessthe formationofcalciumcarbonate,theprimarycomponentoftheshellsintwogroupsofmarineorganisms coccolithophoridsaphytoplanktonandforaminiferaasinglecelled,shelledorganismthatisabundantin manymarineenvironments.Whentheseorganismsdie,theirshellssinktothebottomordissolveinthe watercolumn.Thismovementofcarbonthroughtheoceansremovesexcesscarbonfromtheatmosphere andregulatestheearth'sclimate. Overthelastcentury,humanshavechangedtheatmosphere'scompositionbyreleasinglargeamountsof carbondioxide.Thisexcesscarbondioxide,alongwithother'greenhouse'gases,isbelievedtobeheating upouratmosphereandchangingtheworld'sclimate,leadingto'globalwarming'.Therehasbeenmuch debateabouthownaturalprocesses,suchasthecyclingofcarbonthroughphytoplanktonintheoceans,will respondtothesechanges.Willphytoplanktonproductivityincreaseandtherebyabsorbtheextracarbon fromtheatmosphere?Recentstudiessuggestthatnaturalprocessesmayslowtherateofincreaseofcarbon dioxideintheatmosphere,butitisdoubtfulthateithertheearth'soceansoritsforestscanabsorbthe entiretyoftheextracarbonreleasedbyhumanactivity Falkowskietal.2000 [25]. 1 Thiscontentisavailableonlineat PAGE 8 2 CHAPTER1.GLOBALPROCESSES 1.2LandUseChangeandClimateRegulation Theenergysourcethatultimatelydrivestheearth'sclimateisthesun.Theamountofsolarradiation absorbedbytheearthdependsprimarilyonthecharacteristicsofthesurface.Althoughthelinkbetween solarabsorption,thermodynamics,andultimatelyclimateisverycomplex,newerstudiesindicatethat vegetationcoverandseasonalvariationinvegetationcoveraectsclimateonbothglobalandlocalscales. Newgenerationsofatmosphericcirculationmodelsareincreasinglyabletoincorporatemorecomplexdata relatedtotheseparameters Sellersetal.1997 [90].Besidesregulatingtheatmosphere'scomposition,the extentanddistributionofdierenttypesofvegetationovertheglobemodiesclimateinthreemainways: aectingthereectanceofsunlight radiationbalance ; regulatingthereleaseofwatervapor evapotranspiration ;and changingwindpatternsandmoistureloss surfaceroughness Theamountofsolarradiationreectedbyasurfaceisknownasits albedo ;surfaceswithlowalbedoreect asmallamountofsunlight,thosewithhighalbedoreectalargeamount.Dierenttypesofvegetationhave dierentalbedos;foreststypicallyhavelowalbedo,whereasdesertshavehighalbedo.Deciduousforestsare agoodexampleoftheseasonalrelationshipbetweenvegetationandradiationbalance.Inthesummer,the leavesindeciduousforestsabsorbsolarradiationthroughphotosynthesis;inwinter,aftertheirleaveshave fallen,deciduousforeststendtoreectmoreradiation.Theseseasonalchangesinvegetationmodifyclimate incomplexways,bychangingevapotranspirationratesandalbedo IPCC2001 [73]. Vegetationabsorbswaterfromthesoilandreleasesitbackintotheatmospherethrough evapotranspiration ,whichisthemajorpathwaybywhichwatermovesfromthesoiltotheatmosphere.Thisreleaseof waterfromvegetationcoolstheairtemperature.IntheAmazonregion,vegetationandclimateistightly coupled;evapotranspirationofplantsisbelievedtocontributeanestimatedftypercentoftheannual rainfall Salati1987 [85].Deforestationinthisregionleadstoacomplexfeedbackmechanism,reducing evapotranspirationrates,whichleadstodecreasedrainfallandincreasedvulnerabilitytore Lauranceand Williamson2001 [56]. DeforestationalsoinuencestheclimateofcloudforestsinthemountainsofCostaRica.TheMonteverde CloudForestharborsarichdiversityoforganisms,manyofwhicharefoundnowhereelseintheworld. However,deforestationinlower-lyinglands,evenregionsover50kilometersway,ischangingthelocalclimate, leavingthe"cloud"forestcloudless Lawtonetal.2001 [57].Aswindspassoverdeforestedlowlands,clouds areliftedhigher,oftenabovethemountaintops,reducingtheabilityforcloudforeststoform.Removing thecloudsfromacloudforestdriestheforest,soitcannolongersupportthesamevegetationorprovide appropriatehabitatformanyofthespeciesoriginallyfoundthere.Similarpatternsmaybeoccurringin other,lessstudiedmontanecloudforestsaroundtheworld. Dierentvegetationtypesandtopographieshavevarying surfaceroughness ,whichchangetheow ofwindsintheloweratmosphereandinturninuencesclimate.Lowersurfaceroughnessalsotendsto reducesurfacemoistureandincreaseevaporation.Farmersapplythisknowledgewhentheyplanttreesto createwindbreaks Johnsonetal.2003 [50].Windbreaksreducewindspeedandchangethemicroclimate, increasesurfaceroughness,reducesoilerosion,andmodifytemperatureandhumidity.Formanyeldcrops, windbreaksincreaseyieldsandproductioneciency.Theyalsominimizestressonlivestockfromcoldwinds. 1.3SoilandWaterConservation Biodiversityisalsoimportantforglobalsoilandwaterprotection.Terrestrialvegetationinforestsandother uplandhabitatsmaintainwaterqualityandquantity,andcontrolssoilerosion. In watersheds wherevegetationhasbeenremoved,oodingprevailsinthewetseasonanddroughtin thedryseason.Soilerosionisalsomoreintenseandrapid,causingadoubleeect:removingnutrient-rich topsoilandleadingtosiltationindownstreamriverineandultimatelyoceanicenvironments.Thissiltation harmsriverineandcoastalsheriesaswellasdamagingcoralreefs TurnerandRabalais1994 [98]; van Katwijketal.1993 [103]. PAGE 9 3 Oneofthemostproductiveecosystemsonearth, wetlands havewaterpresentatornearthesurfaceof thesoilorwithintherootzone,allyearorforaperiodoftimeduringtheyear,andthevegetationthere isadaptedtotheseconditions.Wetlandsareinstrumentalforthemaintenanceofcleanwateranderosion control.Microbesandplantsinwetlandsabsorbnutrientsandintheprocesslterandpurifywaterof pollutantsbeforetheycanentercoastalorotheraquaticecosystems. Wetlandsalsoreduceood,wave,andwinddamage.Theyretardtheowofoodwatersandaccumulate sedimentsthatwouldotherwisebecarrieddownstreamorintocoastalareas.Wetlandsalsoserveasbreeding groundsandnurseriesforshandsupportthousandsofbirdandotheranimalspecies. 1.4NutrientCycling Nutrientcyclingisyetanothercriticalserviceprovidedbybiodiversityparticularlybymicroorganisms. Fungiandothermicroorganismsinsoilhelpbreakdowndeadplantsandanimals,eventuallyconvertingthis organicmatterintonutrientsthatenrichthesoil Pimenteletal.1995 [75]. Nitrogenisessentialforplantgrowth,andaninsucientquantityofitlimitsplantproductioninboth naturalandagriculturalecosystems.Whilenitrogenisabundantintheatmosphere,onlyafeworganisms commonlyknownasnitrogen-xingbacteriacanuseitinthisform.Nitrogen-xingbacteriaextract nitrogenfromtheair,andtransformitintoammonia,thenotherbacteriafurtherbreakdownthisammonia intonitrogenouscompoundsthatcanbeabsorbedandusedbymostplants.Inadditiontotheirrolein decompositionandhencenutrientcycling,microorganismsalsohelpdetoxifywaste,changingwasteproducts intoformslessharmfultohumans. 1.5PollinationandSeedDispersal Anestimated90percentofoweringplantsdependonpollinatorssuchaswasps,birds,bats,andbees, toreproduce.Plantsandtheirpollinatorsareincreasinglythreatenedaroundtheworld Buchmannand Nabhan1995 [13]; KremenandRicketts2000 [54].Pollinationiscriticaltomostmajorcropsandvirtually impossibletoreplace.Forinstance,imaginehowcostlyfruitwouldbeandhowlittlewouldbeavailableif itsnaturalpollinatorsnolongerexistedandeachdevelopingowerhadtobefertilizedbyhand. Manyanimalspeciesareimportantdispersersofplantseeds.Ithasbeenhypothesizedthattheloss ofaseeddispersercouldcauseaplanttobecomeextinct.Atpresent,thereisnoexamplewherethishas occurred.Afamousexamplethathasoftenbeencitedpreviouslyisthecaseofthedodo Raphuscucullatus andthetambalacoque Sideroxylongrandiorum .Thedodo,alargeightlessbirdthatinhabitedtheisland ofMauritiusintheIndianOcean,becameextinctduetooverhuntinginthelateseventeenthcentury.It wasoncethoughtthatthetambalacoque,anowendangeredtree,dependeduponthedodotogerminateits hard-casedseeds Temple1977 [96].Inthe1970s,only13treesremainedanditwasthoughtthetreehad notreproducedfor300years.Theseedsofthetreehaveaveryhardcoat,asanexperimenttheywerefed toaturkey;afterpassingthroughitsgizzardtheseedswereviableandgerminated.Thisexperimentled scientiststobelievethattheextinctionofthedodowascoupledtothetambalacoque'sinabilitytoreproduce. However,thishypothesishasnotstooduptofurtherscrutiny,astherewereseveralotherspeciesincluding threenowextinctspecies,alarge-billedparrot,agianttortoise,andagiantlizardthatwerealsocapable ofcrackingtheseed WitmarandCheke1991 [111]; Catling2001 [16].Thusmanyfactors,includingthe lossofthedodo,couldhavecontributedtothedeclineofthetambalacoque.Forfurtherdetailsofcauses ofextinctionseeHistoricalPerspectivesonExtinctionandtheCurrentBiodiversityCrisis.Unfortunately, declinesand/orextinctionsofspeciesareoftenunobservedandthusitisdiculttoteaseoutthecause oftheendresult,asmultiplefactorsareoftenoperatingsimultaneously.Similarproblemsexisttodayin understandingcurrentpopulationdeclines.Forexample,inagivenspecies,populationdeclinesmaybe causedbylossofhabitat,lossinpreyspeciesorlossofpredators,acombinationofthesefactors,orpossibly someotheryetunidentiedcause,suchasdisease. InthepineforestsofwesternNorthAmerica,corvidsincludingjays,magpies,andcrows,squirrels, PAGE 10 4 CHAPTER1.GLOBALPROCESSES andbearsplayaroleinseeddispersal.TheClark'snutcracker Nucifragacolumbiana isparticularlywell adaptedtodispersalofwhitebarkpine Pinusalbicaulis seeds Lanner1996 [55].Thenutcrackerremoves thewinglessseedsfromthecones,whichotherwisewouldnotopenontheirown.Nutcrackershidethe seedsinclumps.Whentheuneatenseedseventuallygrow,theyareclustered,accountingforthetypical distributionpatternofwhitebarkpineintheforest. Intropicalareas,largemammalsandfrugivorousbirdsplayakeyroleindispersingtheseedsoftreesand maintainingtreediversityoverlargeareas.Forexample,three-wattledbellbirds Procniastricarunculata areimportantdispersersoftreeseedsofmembersoftheLauraceaefamilyinCostaRica.Becausebellbirds returnagainandagaintooneormorefavoriteperches,theytakethefruitanditsseedsawayfromthe parenttree,spreadingLauraceaetreesthroughouttheforest WennyandLevy1998 [107]. PAGE 11 Chapter2 DenitionofBiodiversity 1 Biodiversity,acontractionofthephrase"biologicaldiversity,"isacomplextopic,coveringmanyaspects ofbiologicalvariation.Inpopularusage,theword biodiversity isoftenusedtodescribeallthespecies livinginaparticulararea.Ifweconsiderthisareaatitslargestscale-theentireworld-thenbiodiversity canbesummarizedas"lifeonearth."However,scientistsuseabroaderdenitionofbiodiversity,designed toincludenotonlylivingorganismsandtheircomplexinteractions,butalsointeractionswiththeabiotic non-livingaspectsoftheirenvironment.Denitionsemphasizingoneaspectoranotherofthisbiological variationcanbefoundthroughoutthescienticandlayliteraturesee Gaston,1996:Table1.1 [32].Forthe purposesofthismodule, biodiversity isdenedas: thevarietyoflifeonEarthatallitslevels,fromgenestoecosystems,andtheecologicaland evolutionaryprocessesthatsustainit. Geneticdiversityisthefundamentalcurrencyofdiversity WilliamsandHumphires,1996 [110]thatis responsibleforvariationbetweenindividuals,populationsandspecies.Therefore,itisanimportantaspect ofanydiscussionofbiodiversity.Theinteractionsbetweentheindividualorganisms e.g. ,reproductive behavior,predation,parasitismofapopulationorcommunity,andtheirspecializationsfortheirenvironment includingwaysinwhichtheymightmodifytheenvironmentitselfareimportantfunctionalaspectsof biodiversity.Thesefunctionalaspectscandeterminethediversityofdierentcommunitiesandecosystems. Thereisalsoanimportantspatialcomponenttobiodiversity.Thestructureofcommunitiesandecosystems e.g. thenumberofindividualsandspeciespresentcanvaryindierentpartsoftheworld.Similarly, thefunctionofthesecommunitiesandecosystems i.e. theinteractionsbetweentheorganismspresentcan varyfromoneplacetoanother.Dierentassemblagesofecosystemscancharacterizequitediverselandscapes,coveringlargeareas.Thesespatialpatternsofbiodiversityareaectedbyclimate,geology,and physiography RedfordandRichter,1999 [79]. Thestructural,functional,andspatialaspectsofbiodiversitycanvaryovertime;thereforethereisatemporalcomponenttotheanalysisofbiodiversity.Forexample,therecanbedaily,seasonal,orannualchanges inthespeciesandnumberoforganismspresentinanecosystemandhowtheyinteract.Someecosystems changeinsizeorstructureovertime e.g. forestecosystemsmaychangeinsizeandstructurebecauseof theeectsofnaturalres,wetlandsgraduallysiltupanddecreaseinsize.Biodiversityalsochangesover alonger-term,evolutionary,time-scale.Geologicalprocesses e.g. platetectonics orogenesis ,erosion, changesinsea-levelmarinetransgressionsandregressions,andchangesinclimatecausesignicant,longtermchangestothestructuralandspatialcharacteristicsofglobalbiodiversity.Theprocessesofnatural selectionandspeciesevolution,whichmayoftenbeassociatedwiththegeologicalprocesses,alsoresultin changestolocalandglobaloraandfauna. Manypeopleconsiderhumanstobeapartofnature,andthereforeapartofbiodiversity.Ontheother hand,somepeople e.g. RedfordandRichter,1999 [79]connebiodiversitytonaturalvarietyandvariability, 1 Thiscontentisavailableonlineat PAGE 12 6 CHAPTER2.DEFINITIONOFBIODIVERSITY excludingbioticpatternsandecosystemsthatresultfromhumanactivity,eventhoughitisdiculttoassess the"naturalness"ofanecosystembecausehumaninuenceissopervasiveandvaried Hunter,1996 [40]; Angermeier,2000 [2]; Sandersonetal.,2002 [86].Ifonetakeshumansaspartofnature,thenculturaldiversity ofhumanpopulationsandthewaysthatthesepopulationsuseorotherwiseinteractwithhabitatsandother speciesonEarthareacomponentofbiodiversitytoo.Otherpeoplemakeacompromisebetweentotally includingorexcludinghumanactivitiesasapartofbiodiversity.Thesebiologistsdonotacceptallaspectsof humanactivityandcultureaspartofbiodiversity,buttheydorecognizethattheecologicalandevolutionary diversityofdomesticspecies,andthespeciescompositionandecologyofagriculturalecosystemsarepart ofbiodiversity.ForfurtherdiscussionseethemodulesonHumanevolutionandCulturalDiversity;in preparation. PAGE 13 Chapter3 SpatialGradientsinBiodiversity 1 Generallyspeaking,warmtropicalecosystemsarericherinspeciesthancoldtemperateecosystemsathigh latitudessee GastonandWilliams,1996 [34],forgeneraldiscussion.Asimilarpatternisseenforhigher taxonomicgroupsgenera,families.Varioushypotheses e.g. ,environmentalpatchiness,solarenergy,productivity;see BlackburnandGaston,1996 [11]havebeenraisedtoexplainthesepatterns.Forexample,it isassumedthatwarm,moist,tropicalenvironments,withlongday-lengthsprovideorganismswithmoreresourcesforgrowthandreproductionthanharshenvironmentswithlowenergyresources Hunter,2002 [41]. Whenenvironmentalconditionsfavorthegrowthandreproductionofprimaryproducers e.g. ,aquaticalgae, corals,terrestrialorathenthesemaysupportlargenumbersofsecondaryconsumers,suchassmallherbivores,whichalsosupportamorenumerousanddiversefaunaofpredators.Incontrast,thedevelopment ofprimaryproducersincoldertemperateecosystemsisconstrainedbyseasonalchangesinsunlightand temperature.Consequently,theseecosystemsmaysupportalessdiversebiotaofsecondaryconsumersand predators. Recently, Allenetal.2002 [1]developedamodelfortheeectofambienttemperatureonmetabolism, andhencegenerationtimeandspeciationrates,andusedthismodeltoexplainthelatitudinalgradientin biodiversity.However,theseauthorsalsonotedthattheprinciplesthatunderliethesespatialpatternof biodiversityarestillnotwellunderstood. Speciesandecosystemdiversityisalsoknowntovarywithaltitude Walter [105]and Gastonand Williams:214-215 [34].Mountainousenvironments,alsocalled orobiomes ,aresubdividedvertically intoaltitudinalbelts,suchasmontane,alpineandnival,thathavequitedierent ecosystems .Climatic conditionsathigherelevations e.g. ,lowtemperatures,highariditycancreateenvironmentswhererelatively fewspeciescansurvive.Similarly,inoceansandfreshwatersthereareusuallyfewerspeciesasonemovesto increasingdepthsbelowthesurface.However,intheoceanstheremaybeariseinspeciesrichnesscloseto theseabed,whichisassociatedwithanincreaseinecosystemheterogeneity. Bymappingspatialgradientsinbiodiversitywecanalsoidentifyareasofspecialconservationinterest. Conservationbiologistsareinterestedinareasthathaveahighproportionof endemicspecies i.e. ,species whosedistributionsarenaturallyrestrictedtoalimitedarea.Itisobviouslyimportanttoconservethese areasbecausemuchoftheiroraandfauna,andthereforetheecosystemsso-formed,arefoundnowhere else.Areasofhighendemismarealsooftenassociatedwithhigh speciesrichness see GastonandSpicer, 1998 [33]forreferences. Someconservationbiologistshavefocusedtheirattentiononareasthathavehighlevelsofendemismand hencediversitythatarealsoexperiencingahighrateoflossofecosystems;theseregionsare biodiversity hotspots .Becausebiodiversityhotspotsarecharacterizedbylocalizedconcentrationsofbiodiversityunder threat,theyrepresentprioritiesforconservationaction Sechrestetal.,2002 [89].A terrestrialbiodiversityhotspot isdenedquantitativelyasanareathathasatleast0.5%,or1,500oftheworld'sca.300,000 speciesofgreenplants Viridiplantae ,andthathaslostatleast70%ofitsprimaryvegetation Myerset 1 Thiscontentisavailableonlineat PAGE 14 8 CHAPTER3.SPATIALGRADIENTSINBIODIVERSITY al.,2000 [70]; ConservationInternational,2002 [46]. Marinebiodiversityhotspots arequantitatively denedbasedonmeasurementsofrelativeendemismofmultipletaxaspeciesofcorals,snails,lobsters, sheswithinaregionandtherelativelevelofthreattothatregion Robertsetal.,2002 [81].According tothisapproach,thePhilippinearchipelagoandtheislandsofBioko,SaoTome,PrincipeandAnnobonin theeasternAtlanticGulfofGuineaarerankedastwoofthemostthreatenedmarinebiodiversityhotspot regions. Conservationbiologistsmayalsobeinterestedin biodiversitycoldspots ;theseareareasthathave relativelylowbiologicaldiversitybutalsoincludethreatenedecosystems KareivaandMarvier,2003 [51]. Althoughabiodiversitycoldspotislowinspeciesrichness,itcanalsobeimportanttoconserve,asitmaybe theonlylocationwhereararespeciesisfound.Extremephysicalenvironmentsloworhightemperatures orpressures,orunusualchemicalcompositioninhabitedbyjustoneortwospeciallyadaptedspeciesare coldspotsthatwarrantconservationbecausetheyrepresentuniqueenvironmentsthatarebiologicallyand physicallyinteresting.Forfurtherdiscussiononspatialgradientsinbiodiversityandassociatedconservation practicesseetherelatedmoduleson"Whereistheworld'sbiodiversity?"and"ConservationPlanningata RegionalScale." PAGE 15 Chapter4 IntroductiontotheBiodiversity Hierarchy 1 Toeectivelyconservebiodiversity,weneedtobeabletodenewhatwewanttoconserve,determinewhere itcurrentlyoccurs,identifystrategiestohelpconserveit,andtrackovertimewhetherornotthesestrategies areworking.Therstoftheseitems,deningwhatwewanttoconserve,iscomplicatedbytheremarkable diversityoftheorganismsthemselves.Thisisaproductofthe geneticdiversity oftheorganisms,thatis, variationintheDNAdeoxyribonucleicacidthatmakesupthegenesoftheorganisms. Geneticdiversityamongorganismsexistsatthefollowingdierentlevels: withinasingleindividual; betweendierentindividualsofasinglepopulation; betweendierentpopulationsofasinglespecies populationdiversity ; betweendierentspecies speciesdiversity Itcanbedicult,insomecases,toestablishtheboundariesbetweentheselevelsofdiversity.For example,itmaybediculttointerpretwhethervariationbetweengroupsofindividualsrepresentsdiversity betweendierentspecies,orrepresentsdiversityonlybetweendierentpopulationsofthesamespecies. Nevertheless,ingeneralterms,theselevelsofgeneticdiversityformaconvenienthierarchyfordescribing theoveralldiversityoforganismsonEarth. Similarly,thefunctionalandspatialaspectsofbiodiversitycanalsobediscussedatanumberofdierent levels;forexample,diversitywithinorbetween communities ecosystems landscapes ,biogeographical regions,and ecoregions 1 Thiscontentisavailableonlineat PAGE 16 10 CHAPTER4.INTRODUCTIONTOTHEBIODIVERSITYHIERARCHY PAGE 17 Chapter5 WhatisBiodiversity?Acomparisonof spidercommunities 1 5.1Objectives Toexplorethroughclassicationoflifeformstheconceptofbiologicaldiversityasitoccursatvarious taxonomiclevels. 5.2Procedures Spidersareahighlyspeciesrichgroupofinvertebratesthatexploitawidevarietyofnichesinvirtually alltheearth'sbiomes.Somespeciesofspidersbuildelaboratewebsthatpassivelytraptheirpreywhereas othersareactivepredatorsthatambushorpursuetheirprey.Givenspiders'taxonomicdiversityaswellas thevarietyofecologicalnichesbreadthalongwiththeeaseofcatchingthem,spiderscanrepresentuseful, fairlyeasilymeasuredindicatorsofenvironmentalchangeandcommunityleveldiversity. Thisexercisefocusesonclassifyingandanalyzingspidercommunitiestoexploretheconceptofbiological diversityandexperienceitsapplicationtodecisionmakinginbiologicalconservation.Theexercisecanbe undertakeninthreeparts,dependingonyourinterestlevel. Level -Youwillgainexperienceinclassifyingorganismsbysortingahypotheticalcollectionof spidersfromaforestpatchanddeterminingifthespidercollectionisadequatetoaccuratelyrepresent theoveralldiversityofspiderspresentintheforestpatch. Level -Ifyouwishtoexplorefurther,youcansortspidercollectionsmadeatfourotherforest patchesinthesameregionandcontrastspidercommunitiesintermsoftheirspeciesrichness,species diversity,andcommunitysimilarity.Youwillapplythisinformationtomakedecisionsaboutthe prioritythatshouldbegiventoprotectingeachforestpatchinordertoconservetheregionalpoolof spiderdiversity. Level -Ifyouwishtoexploretheconceptsofbiodiversityyetfurther,youwillnexttakeinto accounttheevolutionaryrelationshipsamongthefamiliesofspiderscollected.Thisphylogenetic perspectivewillaugmentyourdecisionmakingaboutprioritiesforpatchprotectionbyaccounting forevolutionarydistinctivenessinadditiontodiversityanddistinctivenessatthecommunitylevel. Onceyouhaveworkedthroughtheseconceptsandanalysesyouwillhaveamuchenhancedfamiliaritywith thesubtletiesofwhatbiologicaldiversityis. 1 Thiscontentisavailableonlineat PAGE 18 12 CHAPTER5.WHATISBIODIVERSITY?ACOMPARISONOFSPIDER COMMUNITIES 5.3Level1:SortingandClassifyingaSpiderCollectionandAssessingitsComprehensiveness Obtainapapercopyofthespidercollectionforforestpatch"1."Thespiderswerecapturedbyabiologist travelingalongtransectsthroughthepatchandstrikingarandomseriesof100treebranches.Allspiders dislodgedthatfellontoanoutstretchedsheetwerecollectedandpreservedinalcohol.Theyhavesincebeen spreadoutonatrayforyoutoexamine.Thespidercollectionishypotheticalbutthespeciespicturedare actualspidersthatoccurincentralAfricaillustrationsusedarefrom Berland1955 [9]. Thenexttaskisforyoutosortandidentifythespiders.Todothisyouhavetoidentifyallthespecimens inthecollection.Toclassifythespiderslookforexternalcharactersthatallmembersofaparticulargroupof spidershaveincommonbutthatarenotsharedbyothergroupsofspiders.Forexample,leglength,hairiness, relativesizeofbodysegments,orabdomenpatterningandabdomenshapeallmightbeusefulcharacters. Lookforgroupsofmorphologicallyindistinguishablespiders,anddescribebrieythesetofcharactersunique toeachgroup.Theseoperationaltaxonomicunitsthatyoudenewillbeconsideredseparatespecies.To assistyouinclassifyingtheseorganisms,adiagramofkeyexternalmorphologicalcharactersofbeetlesis providedFigure5.1.Notethatmostspideridenticationdependsoncloseexaminationofspidergenitalia. Forthisexercise,however,wewillbeexamininggrossexternalcharacteristicsofmorphologicallydissimilar species. PAGE 19 13 Figure5.1: Basicexternalcharacteristicsofspidersusefulforidentifyingindividualstospecies. Assigneachspeciesaworkingname,preferablysomethingdescriptive.Forexample,youmightcalla particularspecies"spottedabdomen,veryhairy"or"shortlegs,spikyabdomen"Justrememberthatthe moreusefulnameswillbethosethatsignifytoyousomethinguniqueaboutthespecies.Constructatable listingeachspecies,itsdistinguishingcharacteristics,thenameyouhaveappliedtoit,andthenumberof occurrencesofthespeciesinthecollectionFigure5.2. PAGE 20 14 CHAPTER5.WHATISBIODIVERSITY?ACOMPARISONOFSPIDER COMMUNITIES Figure5.2 PAGE 21 15 Last,askwhetherthiscollectionadequatelyrepresentsthetruediversityofspidersintheforestpatch atthetimeofcollection.Weremostofthespeciespresentsampledorweremanylikelymissed?Thisis alwaysanimportantquestiontoasktoensurethatthesamplewasadequateandhencecanbelegitimately contrastedamongsitesto,forexample,assignareasaslowversushighdiversitysites. Todothisyouwillperformasimplebutinformativeanalysisthatisstandardpracticeforconservation biologistswhodobiodiversitysurveys.Thisanalysisinvolvesconstructingaso-called collector'scurve ColwellandCoddington1994 [18].Theseplotthecumulativenumberofspeciesobservedy-axisagainst thecumulativenumberofindividualsclassiedx-axis.Thecollector'scurveisanincreasingfunctionwith aslopethatwilldecreaseasmoreindividualsareclassiedandasfewerspeciesremaintobeidentied Figure5.3.Ifsamplingstopswhilethecollector'scurveisstillrapidlyincreasing,samplingisincomplete andmanyspecieslikelyremainundetected.Alternatively,iftheslopeofthecollector'scurvereacheszero attensout,samplingislikelymorethanadequateasfewtononewspeciesremainundetected. Figure5.3: Anexampleofacollectorscurve.Cumulativesamplesizerepresentsthenumberof individualsclassied.Thecumulativenumberoftaxasampledreferstothenumberofnewspecies detected. Toconstructthecollector'scurveforthisspidercollection,chooseaspecimenwithinthecollectionat random.Thiswillbeyourrstdatapoint,suchthat X =1 and Y =1 becauseafterexaminingthe rstindividualyouhavealsoidentiedonenewspecies!Nextmoveconsistentlyinanydirectiontoanew specimenandrecordwhetheritisamemberofanewspecies.Inthisnextstep, X =2 ,but Y mayremain as1ifthenextindividualisnotofanewspeciesoritmaychangeto2iftheindividualrepresentsanew speciesdierentfromindividual1.Repeatthisprocessuntilyouhaveproceededthroughall50specimens andconstructthecollector'scurvefromthedataobtainedjustplot Y versus X .Doesthecurveatten out?Ifso,afterhowmanyindividualspidershavebeencollected?Ifnot,isthecurvestillincreasing?What PAGE 22 16 CHAPTER5.WHATISBIODIVERSITY?ACOMPARISONOFSPIDER COMMUNITIES canyouconcludefromtheshapeofyourcollector'scurveastowhetherthesampleofspidersisanadequate characterizationofspiderdiversityatthesite? 5.4Level2:Contrastingspiderdiversityamongsitestoprovidea basisforprioritizingconservationeorts Inthispartoftheexerciseyouareprovidedwithspidercollectionsfrom4otherforestpatches.Theforest patcheshaveresultedfromfragmentationofaoncemuchlarger,continuousforest.Youwillusethespider diversityinformationtoprioritizeeortsforthevedierentforestpatchesincludingthedatafromthe rstpatchwhichyouhavealreadyclassied.Herearetheadditionalspidercollections:SeeFigure5.4, Figure5.5,Figure5.6,andFigure5.7 PAGE 23 17 Figure5.4 PAGE 24 18 CHAPTER5.WHATISBIODIVERSITY?ACOMPARISONOFSPIDER COMMUNITIES Figure5.5 PAGE 25 19 Figure5.6 PAGE 26 20 CHAPTER5.WHATISBIODIVERSITY?ACOMPARISONOFSPIDER COMMUNITIES Figure5.7 Again,tallyhowmanyindividualsbelongingtoeachspeciesoccurineachsite'sspidercollectionuse yourclassicationofspiderscompletedforSite1Figure5.2duringLevel1oftheexercise.Specically, PAGE 27 21 constructatableofspeciesrowsbysitecolumns.Inthetable'scellsputthenumberofindividuals ofeachspeciesyoufoundinthecollectionfromtheisland.Youcanthenanalyzethesedatatogenerate dierentmeasuresofcommunitycharacteristicstohelpyoutodecidehowtoprioritizeprotectionofthe forestpatches.Recallthatyouneedtorankthepatchesintermsofwhereprotectioneortsshouldbe applied,andyouneedtoprovidearationaleforyourranking. Youwillnditmostusefultobaseyourdecisionsonthreecommunitycharacteristics:speciesrichness andspeciesdiversitywithineachforestpatch,andthesimilarityofspidercommunitiesbetweenpatches. Speciesrichnessissimplythetallyofdierentspiderspeciesthatwerecollectedinaforestpatch.Species diversityisamorecomplexconcept.WewilluseastandardindexcalledSimpsonReciprocalIndex, 1 D where D iscalculatedasfollows: D = X )]TJ/F11 9.9626 Tf 4.566 -8.07 Td [(p i 2 where p i =thefractionalabundanceofthe i th speciesonanisland.Forexample,ifyouhadasampleof twospecieswithveindividualseach, D = 1 0 : 5 2 +0 : 5 2 =2 .Thehigherthevalue,thegreaterthediversity. Themaximumvalueisthenumberofspeciesinthesample,whichoccurswhenallspeciescontainanequal numberofindividuals.Becausethisindexnotonlyreectsthenumberofspeciespresentbutalsotherelative distributionofindividualsamongspecieswithinacommunityitcanreecthowbalancedcommunitiesare intermsofhowindividualsaredistributedacrossspecies.Asaresult,twocommunitiesmayhaveprecisely thesamenumberofspecies,andhencespeciesrichness,butsubstantiallydierentdiversitymeasuresif individualsinonecommunityareskewedtowardafewofthespecieswhereasindividualsaredistributed moreevenlyintheothercommunity. Diversityisonething,distinctivenessisquiteanother.Thusanotherimportantperspectiveinranking sitesishowdierentthecommunitiesarefromoneanother.Wewillusethesimplestavailablemeasure ofcommunitysimilarity,thatis,theJaccardcoecientofcommunitysimilarity,tocontrastcommunity distinctivenessbetweenallpossiblepairsofsites: CC j = c S where c isthenumberofspeciescommontobothcommunitiesand S isthetotalnumberofspeciespresent inthetwocommunities.Forexample,ifonesitecontainsonly2speciesandtheothersite2species,oneof whichisheldincommonbybothsites,thetotalnumberofspeciespresentis3andthenumbersharedis 1,so 1 = 3=33 %.Thisindexrangesfrom0whennospeciesarefoundincommonbetweencommunities to1whenallspeciesarefoundinbothcommunities.Calculatethisindextocompareeachpairofsites separately,thatis,compareSite1Figure5.2withSite2Figure5.4,Site1Figure5.2withSite3 Figure5.5, ::: ,Site4Figure5.6withSite5Figure5.7for10totalcomparisons.Youmightndit usefultodeterminetheaveragesimilarityofonecommunitytoalltheothers,byaveragingthe CC j values acrosseachcomparisonaparticularsiteisincluded. OnceyouhavemadethesecalculationsofdiversityspeciesrichnessandSimpson'sReciprocalIndex youcantackletheprimaryquestionoftheexercise:Howshouldyourankthesesitesforprotectionand why?Makinganinformeddecisionrequiresreconcilingyouranalysiswithconceptsofbiologicaldiversityas itpertainstodiversityanddistinctiveness.Whatdoyourecommend? 5.5Level3:Consideringevolutionarydistinctiveness Whencontrastingpatternsofspeciesdiversityandcommunitydistinctiveness,wetypicallytreateachspecies asequallyimportant,yetarethey?Whatifaspecies-poorareaactuallyisquiteevolutionarilydistinctfrom others?Similarly,whatifyourmostspecies-richsiteiscomprisedofaswarmofspeciesthathaveonlyrecently divergedfromoneanotherandarequitesimilartospeciespresentatanothersite?Thesequestionsallude toissuesofbiologicaldiversityathighertaxonomiclevels.Onlybylookingattheunderlyingevolutionary relationshipsamongspeciescanwegainthisadditionalperspective.WehaveprovidedinFigure5.8a phylogenyofthespiderfamiliesthatoccurinyourcollectionsagenuinephylogenyforthesefamiliesbasedin PAGE 28 22 CHAPTER5.WHATISBIODIVERSITY?ACOMPARISONOFSPIDER COMMUNITIES largeparton CoddingtonandLevi1991 [17].Inbrief,themorecloselyrelatedfamiliesandspeciestherein arelocatedonmoreproximalbrancheswithinthephylogeny.Basedontheevolutionaryrelationshipsamong thesefamilies,willyoumodifyanyoftheconclusionsyoumadeonprioritizingforestpatchesforprotection basedonpatternsofspeciesdiversityalone?Ifso,why? PAGE 29 23 Figure5.8 PAGE 30 24 CHAPTER5.WHATISBIODIVERSITY?ACOMPARISONOFSPIDER COMMUNITIES PAGE 31 Chapter6 SpeciesDiversity 1 Strictlyspeaking, speciesdiversity isthenumberofdierentspeciesinaparticulararea speciesrichness weightedbysomemeasureofabundancesuchasnumberofindividualsorbiomass.However,itis commonforconservationbiologiststospeakofspeciesdiversityevenwhentheyareactuallyreferringto speciesrichness. Anothermeasureofspeciesdiversityisthe speciesevenness ,whichistherelativeabundancewith whicheachspeciesisrepresentedinanarea.An ecosystem whereallthespeciesarerepresentedbythe samenumberofindividualshashighspeciesevenness.Anecosystemwheresomespeciesarerepresentedby manyindividuals,andotherspeciesarerepresentedbyveryfewindividualshasalowspeciesevenness.Table 6.1:EstimatedNumbersofDescribedSpecies,BasedonLecointreandGuyadershowstheabundance ofspeciesnumberofindividualsperhectareinthreeecosystemsandgivesthemeasuresofspeciesrichness S,evennessE,andtheShannondiversityindexH. Shannon'sdiversityindex H = )]TJ/F8 9.9626 Tf 9.409 0 Td [( P i ln i i istheproportionofthetotalnumberofspecimens i expressedasaproportionofthetotalnumber ofspeciesforallspeciesintheecosystem.Theproductof i ln i foreachspeciesintheecosystemis summed,andmultipliedby )]TJ/F8 9.9626 Tf 7.749 0 Td [(1 togive H .Thespeciesevennessindex E iscalculatedas E = H H max H max isthemaximumpossiblevalueof H ,andisequivalentto ln S .Thus E = H ln S See Gibbsetal.,1998:p157 [35]and Bealsetal. [8]fordiscussionandexamples. Magurran [61] alsogivesdiscussionofthemethodsofquantifyingdiversity. InTable6.1:EstimatedNumbersofDescribedSpecies,BasedonLecointreandGuyader,ecosystemAshowsthegreatestdiversityintermsofspeciesrichness.However,ecosystemBcouldbedescribedas being richer insofarasmostspeciespresentaremoreevenlyrepresentedbynumbersofindividuals;thusthe speciesevennessEvalueislarger.Thisexamplealsoillustratesaconditionthatisoftenseenintropical ecosystems,wheredisturbanceoftheecosystemcausesuncommonspeciestobecomeevenlesscommon,and commonspeciestobecomeevenmorecommon.DisturbanceofecosystemBmayproduceecosystemC, wheretheuncommonspecies3hasbecomelesscommon,andtherelativelycommonspecies1hasbecome morecommon.Theremayevenbeanincreaseinthenumberofspeciesinsomedisturbedecosystemsbut,as notedabove,thismayoccurwithaconcomitantreductionintheabundanceofindividualsorlocalextinction oftherarerspecies. Speciesrichnessandspeciesevennessareprobablythemostfrequentlyusedmeasuresofthetotalbiodiversityofaregion.Speciesdiversityisalsodescribedintermsofthe phylogeneticdiversity ,orevolutionary relatedness,ofthespeciespresentinanarea.Forexample,someareasmayberichincloselyrelatedtaxa, havingevolvedfromacommonancestorthatwasalsofoundinthatsamearea,whereasotherareasmay haveanarrayoflesscloselyrelatedspeciesdescendedfromdierentancestorsseefurthercommentsinthe sectiononSpeciesdiversityasasurrogateforglobalbiodiversityp.27. 1 Thiscontentisavailableonlineat PAGE 32 26 CHAPTER6.SPECIESDIVERSITY Tocountthenumberofspecies,wemustdenewhatconstitutesaspecies.Thereareseveralcompeting theories,or"speciesconcepts" Mayden,1997 [62].Themostwidelyacceptedarethemorphologicalspecies concept,thebiologicalspeciesconcept,andthephylogeneticspeciesconcept. Althoughthe morphologicalspeciesconcept MSCislargelyoutdatedasatheoreticaldenition,it isstillwidelyused.Accordingtothisconcept: speciesarethesmallestgroupsthatareconsistentlyandpersistentlydistinct,anddistinguishable byordinarymeans.Cronquist,1978 [ ? ] Inotherwords, morphologicalspeciesconcept statesthat"aspeciesisacommunity,oranumberofrelatedcommunities,whosedistinctivemorphologicalcharactersare,intheopinionofacompetentsystematist, sucientlydenitetoentitleit,orthem,toaspecicname" Regan,1926:75 [80]. The biologicalspeciesconcept BSC,asdescribedby MayrandAshlock [64],statesthat "aspeciesisagroupofinterbreedingnaturalpopulationsthatisreproductivelyisolatedfrom othersuchgroups". Accordingtothe phylogeneticspeciesconcept PSC,asdenedby Cracraft [19],aspecies: "isthesmallestdiagnosableclusterofindividualorganism[thatis,theclusteroforganismsare identiablydistinctfromotherclusters]withinwhichthereisaparentalpatternofancestryand descent". Theseconceptsarenotcongruent,andconsiderabledebateexistsabouttheadvantagesanddisadvantages ofallexistingspeciesconceptsforfurtherdiscussion,seethemoduleonMacroevolution:essentialsof systematicsandtaxonomy. Inpractice,systematistsusuallygroupspecimenstogetheraccordingtosharedfeaturesgenetic,morphological,physiological.Whentwoormoregroupsshowdierentsetsofsharedcharacters,andtheshared charactersforeachgroupallowallthemembersofthatgrouptobedistinguishedrelativelyeasilyandconsistentlyfromthemembersofanothergroup,thenthegroupsareconsidereddierentspecies.Thisapproach reliesontheobjectivityofthephylogeneticspeciesconcept i.e. ,theuseofintrinsic,shared,charactersto deneordiagnoseaspeciesandappliesittothepracticalityofthemorphologicalspeciesconcept,interms ofsortingspecimensintogroups Kottelat,1995 [52], 1997 [53]. Despitetheirdierences,allspeciesconceptsarebasedontheunderstandingthatthereareparameters thatmakeaspeciesadiscreteandidentiableevolutionaryentity.Ifpopulationsofaspeciesbecome isolated,eitherthroughdierencesintheirdistribution i.e. ,geographicisolationorthroughdierencesin theirreproductivebiology i.e. ,reproductiveisolation,theycandiverge,ultimatelyresultinginspeciation. Duringthisprocess,weexpecttoseedistinctpopulationsrepresenting incipientspecies -speciesin theprocessofformation.Someresearchersmaydescribetheseassubspeciesorsomeothersub-category, accordingtothespeciesconceptusedbytheseresearchers.However,itisverydiculttodecidewhena populationissucientlydierentfromotherpopulationstomerititsrankingasasubspecies.Forthese reasons,subspecicandinfrasubspecicranksmaybecomeextremelysubjectivedecisionsofthedegreeof distinctivenessbetweengroupsoforganisms Kottelat,1997 [53]. An evolutionarysignicantunit ESUisdened,inconservationbiology,asagroupoforganisms thathasundergonesignicantgeneticdivergencefromothergroupsofthesamespecies.Accordingto Ryder, 1986 [84]identicationofESUsrequirestheuseofnaturalhistoryinformation,rangeanddistributiondata, andresultsfromanalysesofmorphometrics,cytogenetics,allozymesandnuclearandmitochondrialDNA. Inpractice,manyESUsarebasedononlyasubsetofthesedatasources.Nevertheless,itisnecessary tocomparedatafromdierentsources e.g. ,analysesofdistribution,morphometrics,andDNAwhen establishingthestatusofESUs.IftheESUsarebasedonpopulationsthatare sympatric or parapatric thenitisparticularlyimportanttogiveevidenceofsignicantgeneticdistancebetweenthosepopulations. ESUsareimportantforconservationmanagementbecausetheycanbeusedtoidentifydiscretecomponentsoftheevolutionarylegacyofaspeciesthatwarrantconservationaction.Nevertheless,inevolutionary termsandhenceinmanysystematicstudies,speciesarerecognizedastheminimumidentiableunitof PAGE 33 27 biodiversityabovethelevelofasingleorganism Kottelat,1997 [53].ThusthereisgenerallymoresystematicinformationavailableforspeciesdiversitythanforsubspeciccategoriesandforESUs.Consequently, estimatesofspeciesdiversityareusedmorefrequentlyasthestandardmeasureofoverallbiodiversityofa region. 6.1SpeciesDiversityasaSurrogateforGlobalBiodiversity GlobalbiodiversityisfrequentlyexpressedasthetotalnumberofspeciescurrentlylivingonEarth, i.e. itsspeciesrichness.Betweenabout1.5and1.75millionspecieshavebeendiscoveredandscientically describedthusfar LeCointreandGuyader,2001 [58]; Cracraft,2002 [20].Estimatesforthenumberof scienticallyvalidspeciesvarypartlybecauseofdieringopinionsonthedenitionofaspecies.Forexample, thephylogeneticspeciesconceptrecognizesmorespeciesthanthebiologicalspeciesconcept.Also,some scienticdescriptionsofspeciesappearinold,obscure,orpoorlycirculatedpublications.Inthesecases, scientistsmayaccidentallyoverlookcertainspecieswhenpreparinginventoriesofbiota,causingthemto describeandnameanalreadyknownspecies. Moresignicantly,somespeciesareverydiculttoidentify.Forexample,taxonomically"crypticspecies" lookverysimilartootherspeciesandmaybemisidentiedandhenceoverlookedasbeingadierentspecies. Thus,severaldierent,butsimilar-lookingspecies,identiedasasinglespeciesbyonescientist,areidentied ascompletelydierentspeciesbyanotherscientist.Forfurtherdiscussionofcrypticspecies,withspecic examplesofcrypticfrogsfromVietnam,see Inger [45]and Bainetal.,inpress [7]. Scientistsexpectthatthescienticallydescribedspeciesrepresentonlyasmallfractionofthetotalnumber ofspeciesonEarthtoday.Manyadditionalspecieshaveyettobediscovered,orareknowntoscientists buthavenotbeenformallydescribed.ScientistsestimatethatthetotalnumberofspeciesonEarthcould rangefromabout3.6millionupto117.7million,with13to20millionbeingthemostfrequentlycitedrange Hammond,1995 [37]; Cracraft,2002 [20]. Theestimationoftotalnumberofspeciesisbasedonextrapolationsfromwhatwealreadyknowabout certaingroupsofspecies.Forexample,wecanextrapolateusingtheratioofscienticallydescribedspeciesto undescribedspeciesofaparticulargroupoforganismscollectedfromaprescribedarea.However,weknowso littleaboutsomegroupsoforganisms,suchasbacteriaandsometypesoffungi,thatwedonothavesuitable baselinedatafromwhichwecanextrapolateourestimatedtotalnumberofspeciesonEarth.Additionally, somegroupsoforganismshavenotbeencomprehensivelycollectedfromareaswheretheirspeciesrichness islikelytoberichestforexample,insectsintropicalrainforests.Thesefactors,andthefactthatdierent peoplehaveuseddierenttechniquesanddatasetstoextrapolatethetotalnumberofspecies,explainthe largerangebetweenthelowerandupperguresof3.6millionand117.7million,respectively. WhileitisimportanttoknowthetotalnumberofspeciesofEarth,itisalsoinformativetohavesome measureoftheproportionalrepresentationofdierentgroupsofrelatedspecies e.g. bacteria,owering plants,insects,birds,mammals.Thisisusuallyreferredtoasthetaxonomicorphylogeneticdiversity. Speciesaregroupedtogetheraccordingtosharedcharacteristicsgenetic,anatomical,biochemical,physiological,orbehavioralandthisgivesusaclassicationofthespeciesbasedontheirphylogenetic,or apparentevolutionaryrelationships.Wecanthenusethisinformationtoassesstheproportionofrelated speciesamongthetotalnumberofspeciesonEarth.Table6.1:EstimatedNumbersofDescribedSpecies, BasedonLecointreandGuyadercontainsaselectionofwell-knowntaxa. PAGE 34 28 CHAPTER6.SPECIESDIVERSITY EstimatedNumbersofDescribedSpecies,BasedonLecointreandGuyader Taxon TaxonCommon Name Numberofspecies described* Naspercentageof totalnumberofdescribedspecies* Bacteria truebacteria 9021 0.5 Archaea archaebacteria 259 0.01 Bryophyta mosses 15000 0.9 Lycopodiophyta clubmosses 1275 0.07 Filicophyta ferns 9500 0.5 Coniferophyta conifers 601 0.03 Magnoliophyta oweringplants 233885 13.4 Fungi fungi 100800 5.8 "Porifera" sponges 10000 0.6 Cnidaria cnidarians 9000 0.5 Rotifera rotifers 1800 0.1 Platyhelminthes atworms 13780 0.8 Mollusca mollusks 117495 6.7 Annelida annelidworms 14360 0.8 Nematoda nematodeworms 20000 1.1 Arachnida arachnids 74445 4.3 Crustacea crustaceans 38839 2.2 Insecta insects 827875 47.4 Echinodermata echinoderms 6000 0.3 Chondrichthyes cartilaginousshes 846 0.05 Actinopterygii ray-nnedbonyshes 23712 1.4 Lissamphibia livingamphibians 4975 0.3 Mammalia mammals 4496 0.3 Chelonia livingturtles 290 0.02 Squamata lizardsandsnakes 6850 0.4 continuedonnextpage PAGE 35 29 Aves birds 9672 0.6 Other 193075 11.0 Table6.1 :*Thetotalnumberofdescribedspeciesisassumedtobe1,747,851.Thisgure,andthe numbersofspeciesfortaxaaretakenfrom LeCointreandGuyader [58]. Mostpublicattentionisfocusedonthebiologyandecologyoflarge,charismaticspeciessuchasmammals, birds,andcertainspeciesoftrees e.g. ,mahogany,sequoia.However,thegreaterpartofEarth'sspecies diversityisfoundinother,generallyoverlookedgroups,suchasmollusks,insects,andgroupsofowering plants. PAGE 36 30 CHAPTER6.SPECIESDIVERSITY PAGE 37 Chapter7 Alpha,Beta,andGammaDiversity 1 Whittaker [108]describedthreetermsformeasuringbiodiversityoverspatialscales:alpha,beta,and gammadiversity. Alphadiversity referstothediversitywithinaparticularareaorecosystem,andis usuallyexpressedbythenumberofspecies i.e. speciesrichness inthatecosystem.Forexample,ifwe aremonitoringtheeectthatBritishfarmingpracticeshaveonthediversityofnativebirdsinaparticular regionofthecountry,thenwemightwanttocomparespeciesdiversitywithindierent ecosystems ,suchas anundisturbeddeciduouswood,awell-establishedhedgerowborderingasmallpasture,andalargearable eld.Wecanwalkatransectineachofthesethreeecosystemsandcountthenumberofspecieswesee; thisgivesusthealphadiversityforeachecosystem;seeTable7.1:Alpha,betaandgammadiversityfor hypotheticalspeciesofbirdsinthreedierentecosystemsthisexampleisbasedonthehypotheticalexample givenby Meeetal.,2002;Table6.1 [66]. Ifweexaminethechangeinspeciesdiversitybetweentheseecosystemsthenwearemeasuringthe betadiversity .Wearecountingthetotalnumberofspeciesthatareuniquetoeachoftheecosystems beingcompared.Forexample,thebetadiversitybetweenthewoodlandandthehedgerowhabitatsis7 representingthe5speciesfoundinthewoodlandbutnotthehedgerow,plusthe2speciesfoundinthe hedgerowbutnotthewoodland.Thus,betadiversityallowsustocomparediversitybetweenecosystems. Gammadiversity isameasureoftheoveralldiversityforthedierentecosystemswithinaregion. Hunter:448[42] denesgammadiversityas"geographic-scalespeciesdiversity".Intheexamplein Table7.1:Alpha,betaandgammadiversityforhypotheticalspeciesofbirdsinthreedierentecosystems, thetotalnumberofspeciesforthethreeecosystems14,whichrepresentthegammadiversity. Alpha,betaandgammadiversityforhypotheticalspeciesofbirdsinthreedierent ecosystems Hypotheticalspecies Woodlandhabitat Hedgerowhabitat Openeldhabitat A X B X C X continuedonnextpage 1 Thiscontentisavailableonlineat PAGE 38 32 CHAPTER7.ALPHA,BETA,ANDGAMMADIVERSITY D X E X F X X G X X H X X I X X J X X K X L X X M X N X Alphadiversity 10 7 3 Betadiversity Woodlandvs. hedgerow:7 Hedgerowvs.open eld:8 Woodlandvs.open eld:13 Gammadiversity 14 Table7.1 PAGE 39 Chapter8 IntroductiontoUtilitarianValuationof Biodiversity 1 Determiningthevalueorworthofbiodiversityiscomplex.Economiststypicallysubdivideutilitarianor usevaluesofbiodiversityinto directusevalue forthosegoodsthatareconsumeddirectly,suchasfood ortimber,and indirectusevalue forthoseservicesthatsupporttheitemsthatareconsumed,including ecosystemfunctionslikenutrientcycling. Thereareseverallesstangiblevaluesthataresometimescalled non-useorpassivevalues ,forthings thatwedon'tusebutwouldconsiderasalossiftheyweretodisappear;theseinclude existencevalue ,the valueofknowingsomethingexistsevenifyouwillneveruseitorseeit,and bequestvalue ,thevalueof knowingsomethingwillbethereforfuturegenerations MoranandPearce1994 [69]. PotentialorOption value referstotheusethatsomethingmayhaveinthefuture;sometimesthisisincludedasausevalue, wehavechosentoincludeitwithinthepassivevaluesherebasedonitsabstractnature.Thecomponents includedwithinthecategoryof"utilitarian"valuesvarysomewhatintheliterature.Forexample,some authorsclassifyspiritual,cultural,andaestheticvaluesasindirectusevalues,whilesothersconsiderthem tobenon-usevalues,dierentiatedfromindirectusevaluessuchasnutrientcyclingbecausespiritual, cultural,andaestheticvaluesforbiodiversityarenotessentialtohumansurvival.Stillothersconsiderthese valuesasseparatecategoriesentirely.Seealso, Callicott1997 [15], Hunter2002 [44], MoranandPearce 1994 [69], PerlmanandAdelson1997 [74], Primack2002 [77], VanDyke2003 [102].Inthismodule,we includespiritual,culturalandaestheticvaluesasasubsetofindirectvaluesorservices,astheyprovidea servicebyenrichingourlivesTable8.1:CategoriesofValuesofBiodiversity. CategoriesofValuesofBiodiversity DirectUseValue Goods IndirectUseValue Services Non-UseValues Food,medicine,buildingmaterial,ber,fuel Atmosphericandclimateregulation,pollination,nutrientrecycling PotentialorOption Value Futurevalueeitherasa goodoraservice continuedonnextpage 1 Thiscontentisavailableonlineat PAGE 40 34 CHAPTER8.INTRODUCTIONTOUTILITARIANVALUATIONOF BIODIVERSITY Cultural,Spiritual,and Aesthetic ExistenceValue Valueofknowingsomethingexists BequestValue Valueofknowingthat somethingwillbethere forfuturegenerations Table8.1 note: SomeauthorschoosetodierentiateCultural,Spiritual,Aesthetic,andNon-UseValues fromthoseservicesthatprovidebasicsurvivalneedssuchastheairwebreathe. PAGE 41 Chapter9 BiodiversityoverTime 1 ThehistoryoflifeonEarthisdescribedinvariouspublicationsandwebsites e.g. Speer,B.R.and A.G.Collins.2000 [92]; Tudge,2000 [97]; LecointreandGuyader,2001 [59]; Maddison,2001 [60] Eldredge, 2002 [24];itisalsodiscussedinthemoduleonMacroevolution:essentialsofsystematicsandtaxonomy.For thecurrentpurposeofunderstandingwhatisbiodiversity,itisonlynecessarytonotethatthatthediversity ofspecies,ecosystemsandlandscapesthatsurroundustodayaretheproductofperhaps3.7billion i.e. 3 : 7 10 9 to3.85billionyearsofevolutionoflifeonEarth Mojzsisetal.,1996 [67]; FedoandWhitehouse, 2002 [26]. Thus,theevolutionaryhistoryofEarthhasphysicallyandbiologicallyshapedourcontemporaryenvironment.AsnotedinthesectiononBiogeographyChapter13,platetectonicsandtheevolutionofcontinents andoceanbasinshavebeeninstrumentalindirectingtheevolutionanddistributionoftheEarth'sbiota. However,thephysicalenvironmenthasalsobeenextensivelymodiedbythesebiota.Manyexistinglandscapesarebasedontheremainsofearlierlifeforms.Forexample,someexistinglargerockformationsare theremainsofancientreefsformed360to440millionyearsagobycommunitiesofalgaeandinvertebrates Veron,2000 [47].Veryoldcommunitiesofsubterraneanbacteriamayhavebeenresponsibleforshaping manygeologicalprocessesduringthehistoryoftheEarth,suchastheconversionofmineralsfromoneform toanother,andtheerosionofrocks FredricksonandOnstott,1996 [30].Theevolutionofphotosynthetic bacteria,sometimebetween3.5and2.75millionyearsago Schopf,1993 [88]; Brasieretal.,2002 [12]; Hayes, 2002 [38],playedanimportantroleintheevolutionoftheEarth'satmosphere.Thesebacteriareleasedoxygenintotheatmosphere,changingit'scompositionfromtheformercompositionofmainlycarbondioxide, withothergasessuchasnitrogen,carbonmonoxide,methane,hydrogenandsulphurgasespresentinsmaller quantities.Itprobablytookover2billionyearsfortheoxygenconcentrationtoreachthelevelitistoday Hayes,2002 [38],buttheprocessofoxygenationoftheatmosphereledtoimportantevolutionarychanges inorganismssothattheycouldutilizeoxygenformetabolism.Theriseofanimalandplantlifeonlandwas associatedwiththedevelopmentofanoxygenrichatmosphere. 1 Thiscontentisavailableonlineat PAGE 42 36 CHAPTER9.BIODIVERSITYOVERTIME PAGE 43 Chapter10 ABriefHistoryofLifeonEarth 1 Thediversityofspecies,ecosystemsandlandscapesthatsurroundustodayaretheproductofperhaps3.7 billion i.e. 3 : 7 10 9 to3.85billionyearsofevolutionoflifeonEarth Mojzsisetal.,1996 [68]; Fedoand Whitehouse,2002 [ ? ].Lifemayhaverstevolvedunderharshconditions,perhapscomparabletothedeepseathermalventswherechemo-autotrophicbacteriaarecurrentlyfoundtheseareorganismsthatobtain theirenergyonlyfrominorganic,chemicalsources. Asubterraneanevolutionoflifehasalsobeensuggested.Rocklayersdeepbelowthecontinentsand oceanoors,thatwerepreviouslythoughttobetoopoorinnutrientstosustainlife,havenowbeenfound tosupportthousandsofstrainsofmicroorganisms.Typesofbacteriahavebeencollectedfromrocksamples almost2milesbelowthesurface,attemperaturesupto75degreesCelsius.Thesechemo-autotrophic microorganismsderivetheirnutrientsfromchemicalssuchascarbon,hydrogen,ironandsulphur.Deep subterraneancommunitiescouldhaveevolvedundergroundororiginatedonthesurfaceandbecomeburied orotherwisetransporteddownintosubsurfacerockstrata,wheretheyhavesubsequentlyevolvedinisolation. Eitherway,theseappeartobeveryoldcommunities,anditispossiblethatthesesubterraneanbacteria mayhavebeenresponsibleforshapingmanygeologicalprocessesduringthehistoryoftheEarth e.g. theconversionofmineralsfromoneformtoanother,andtheerosionofrocks FredricksonandOnstott, 1996 [31]. Theearliestevidenceforphotosyntheticbacteria-suspectedtobecyanobacteria-isdatedatsometime between3.5and2.75billionyearsago Schopf,1993 [ ? ]; Brasieretal.,2002 [ ? ]; Hayes,2002 [ ? ].Theserst photosyntheticorganismswouldhavebeenresponsibleforreleasingoxygenintotheatmosphere. Photosynthesis istheformationofcarbohydratesfromcarbondioxideandwater,throughtheactionoflight energyonalight-sensitivepigment,suchaschlorophyll,andusuallyresultingintheproductionofoxygen. Priortothis,theatmospherewasmainlycomposedofcarbondioxide,withothergasessuchasnitrogen, carbonmonoxide,methane,hydrogenandsulphurgasespresentinsmallerquantities. Itprobablytookover2billionyears,fromtheinitialadventofphotosynthesisfortheoxygenconcentration intheatmospheretoreachthelevelitisattoday Hayes,2002 [ ? ].Asoxygenlevelsrose,someofthe earlyanaerobicspeciesprobablybecameextinct,andothersprobablybecamerestrictedtohabitatsthat remainedfreeofoxygen.Someassumedalifestylepermanentlylodgedinsideaerobiccells.Theanaerobic cellsmight,initially,havebeenincorporatedintotheaerobiccellsafterthoseaerobeshadengulfedthem asfood.Alternatively,theanaerobesmighthaveinvadedtheaerobichostsandbecomeparasiteswithin them.Eitherway,amoreintimatesymbioticrelationshipsubsequentlyevolvedbetweentheseaerobicand anaerobiccells.Inthesecasesthesurvivalofeachcellwasdependentonthefunctionoftheothercell. Theevolutionofthissymbioticrelationshipwasanextremelyimportantstepintheevolutionofmore complexcellsthathaveanucleus,whichisacharacteristicoftheEucaryaoreucaryoteseu=good,ortrue; andkaryon=kernel,ornucleus.RecentstudiesofrocksfromWesternAustraliahavesuggestedthatthe earliestformsofsingle-celledeucaryotesmightbeatleast2.7billionyearsold Anon,2001 [3].According 1 Thiscontentisavailableonlineat PAGE 44 38 CHAPTER10.ABRIEFHISTORYOFLIFEONEARTH tocontemporarytheories,therehasbeensucienttime,overthose2.7billionyears,forsomeofthegenes oftheinvadinganaerobetohavebeenlost,oreventransferredtothenucleusofthehostaerobecell.Asa result,thegenomesoftheancestralinvaderandancestralhosthavebecomemingledandthetwoentities cannowbeconsideredasonefromageneticstandpoint. TheevolutionaryhistoryoftheEucaryaisdescribedinvariousstandardreferencesandsoisnotcovered indetailhere.Briey,eucaryotesconstitutethreewellknowngroups-theViridiplantaeorgreenplants, theFungi,andtheMetazoaoranimals.Therearealsomanybasalgroupsofeucaryotesthatareextremely diverse-andmanyofwhichareevolutionarilyancient.Forexample,theRhodophyta,orredalgae,which mightbethesister-grouptotheViridiplantae,includesfossilrepresentativesdatingfromthePrecambrian, 1025billionyearsago.TheStramenopilesincludessmall,single-celledorganismssuchasdiatoms,funguslikespeciesofwatermouldsanddownymildews,andextremelylarge,multicellularbrownseaweedssuchas kelps. Theearliestknowngreenplantsaregreenalgae,datingfromtheCambrian,atleast500millionyears ago.BytheendoftheDevonian,360millionyearsago,plantshadbecomequitediverseandincluded representativessimilartomodernplants.Greenplantshavebeenextremelyimportantinshapingthe environment.Fueledbysunlight,theyaretheprimaryproducersofcarbohydrates,sugarsthatareessential foodresourcesforherbivoresthatarethenpreytopredatorycarnivores.Theevolutionandecologyof pollinatinginsectsiscloselyassociatedwiththeevolutionoftheAngiosperms,oroweringplants,sincethe JurassicandCretaceousperiods. Fungi,whichdatebacktothePrecambriantimesabout650to540millionyearsago,arealsoimportant inshapingandsustainingbiodiversity.Bybreakingdowndeadorganicmaterialandusingthisfortheir growth,theyrecyclenutrientsbackthroughecosystems.Fungiarealsoresponsibleforcausingseveralplant andanimaldiseases.Fungialsoformsymbioticrelationshipswithtreespecies,ofteninnutrient-poorsoils suchasarefoundinthehumidtropics,allowingtheirsymbionttreestheabilitytoourishinwhatwould otherwisebeadicultenvironment. Metazoa,whichdatetoover500millionyearsagohavealsobeenresponsibleforshapingmanyecosystems, fromthespecializedtubewormsofdeepsea,hydrothermalventcommunitiesoftheoceanoor,tothebirds livinginthehighaltitudesoftheHimalayas,suchastheimpeyanpheasantandTibetansnowcock.Many speciesofanimalsareparasiticonotherspeciesandcansignicantlyaectthebehaviorandlife-cyclesof theirhosts. Thus,theevolutionaryhistoryofEarthhasphysicallyandbiologicallyshapedourcontemporaryenvironment.Manyexistinglandscapesarebasedontheremainsofearlierlifeforms.Forexample,someexisting largerockformationsaretheremainsofancientreefsformed360to440millionyearsagobycommunities ofalgaeandinvertebrates Veron,2000 [48]. PAGE 45 Chapter11 EcosystemDiversity 1 An ecosystem isacommunityplusthephysicalenvironmentthatitoccupiesatagiventime.Anecosystem canexistatanyscale,forexample,fromthesizeofasmalltidepooluptothesizeoftheentirebiosphere. However,lakes,marshes,andforeststandsrepresentmoretypicalexamplesoftheareasthatarecompared indiscussionsofecosystemdiversity. Broadlyspeaking,thediversityofanecosystemisdependentonthephysicalcharacteristicsoftheenvironment,thediversityofspeciespresent,andtheinteractionsthatthespecieshavewitheachotherandwith theenvironment.Therefore,thefunctionalcomplexityofanecosystemcanbeexpectedtoincreasewiththe numberandtaxonomicdiversityofthespeciespresent,andtheverticalandhorizontalcomplexityofthe physicalenvironment.However,oneshouldnotethatsomeecosystemssuchassubmarineblacksmokers, orhotspringsthatdonotappeartobephysicallycomplex,andthatarenotespeciallyrichinspecies, maybeconsideredtobefunctionallycomplex.Thisisbecausetheyincludespeciesthathaveremarkable biochemicalspecializationsforsurvivingintheharshenvironmentandobtainingtheirenergyfrominorganic chemicalsources e.g. ,seediscussionsof RothschildandMancinelli,2001 [83]. ThephysicalcharacteristicsofanenvironmentthataectecosystemdiversityarethemselvesquitecomplexaspreviouslynotedforcommunitydiversityChapter14.Thesecharacteristicsinclude,forexample, thetemperature,precipitation,andtopographyoftheecosystem.Therefore,thereisageneraltrendfor warmtropicalecosystemstobericherinspeciesthancoldtemperateecosystemssee"Spatialgradientsin biodiversityChapter3".Also,theenergyuxintheenvironmentcansignicantlyaecttheecosystem. Anexposedcoastlinewithhighwaveenergywillhaveaconsiderablydierenttypeofecosystemthana low-energyenvironmentsuchasashelteredsaltmarsh.Similarly,anexposedhilltopormountainsideis likelytohavestuntedvegetationandlowspeciesdiversitycomparedtomoreprolicvegetationandhigh speciesdiversityinshelteredvalleyssee Walter,1985 [106],and Smith,1990 [91]forgeneraldiscussionson factorsaectingecosystems,andcomparativeecosystemecology. Environmentaldisturbanceonavarietyoftemporalandspatialscalescanaectthespeciesrichness and,consequently,thediversityofanecosystem.Forexample,riversystemsintheNorthIslandofNew Zealandhavebeenaectedbyvolcanicdisturbanceseveraltimesoverthelast25,000years.Ash-ladenoods runningdowntheriverswouldhaveextirpatedmostoftheshfaunaintherivers,andrecolonizationhas beenpossibleonlybyalimitednumberofdiadromousspecies i.e. ,species,likeeelsandsalmons,that migratebetweenfreshwaterandseawateratxedtimesduringtheirlifecycle.Oncethedisturbedrivers hadrecovered,thediadromousspecieswouldhavebeenabletorecolonizetheriversbydispersalthrough theseafromotherunaectedrivers McDowall,1996 [65]. Nevertheless,moderatelevelsofoccasionaldisturbancecanalsoincreasethespeciesrichnessofanecosystembycreatingspatialheterogeneityintheecosystem,andalsobypreventingcertainspeciesfromdominatingtheecosystem.SeethemoduleonOrganizingPrinciplesoftheNaturalWorldforfurtherdiscussion. Ecosystemsmaybeclassiedaccordingtothedominanttypeofenvironment,ordominanttypeof 1 Thiscontentisavailableonlineat PAGE 46 40 CHAPTER11.ECOSYSTEMDIVERSITY speciespresent;forexample,asaltmarshecosystem,arockyshoreintertidalecosystem,amangroveswamp ecosystem.Becausetemperatureisanimportantaspectinshapingecosystemdiversity,itisalsousedin ecosystemclassication e.g. ,coldwinterdeserts,versuswarmdeserts Udvardy,1975 [99]. Whilethephysicalcharacteristicsofanareawillsignicantlyinuencethediversityofthespecieswithin acommunity,theorganismscanalsomodifythephysicalcharacteristicsoftheecosystem.Forexample,stony coralsScleractiniaareresponsibleforbuildingtheextensivecalcareousstructuresthatarethebasisforcoral reefecosystemsthatcanextendthousandsofkilometers e.g. GreatBarrierReef.Therearelessextensive waysinwhichorganismscanmodifytheirecosystems.Forexample,treescanmodifythemicroclimateand thestructureandchemicalcompositionofthesoilaroundthem.Fordiscussionofthegeomorphicinuencesof variousinvertebratesandvertebratessee Butler,1995 [14]and,forfurtherdiscussionofecosystemdiversity seethemoduleonProcessesandfunctionsofecologicalsystems. PAGE 47 Chapter12 PopulationDiversity 1 A population isagroupofindividualsofthesamespeciesthatshareaspectsoftheirgeneticsor demography morecloselywitheachotherthanwithothergroupsofindividualsofthatspecieswheredemography isthestatisticalcharacteristicofthepopulationsuchassize,density,birthanddeathrates,distribution, andmovementofmigration. Populationdiversitymaybemeasuredintermsofthevariationingeneticandmorphologicalfeatures thatdenethedierentpopulations.Thediversitymayalsobemeasuredintermsofthepopulations' demographics,suchasnumbersofindividualspresent,andtheproportionalrepresentationofdierentage classesandsexes.However,itcanbediculttomeasuredemographyandgenetics e.g. ,allelefrequencies forallspecies.Therefore,amorepracticalwayofdeningapopulation,andmeasuringitsdiversity,isby thespaceitoccupies.Accordingly,a population isagroupofindividualsofthesamespeciesoccupyinga denedareaatthesametime Hunter,2002:144 [42].Theareaoccupiedbyapopulationismosteectively denedbytheecologicalboundariesthatareimportanttothepopulationforexample,aparticularregion andtypeofvegetationforapopulationofbeetles,oraparticularpondforapopulationofsh. Thegeographicrangeanddistributionofpopulations i.e. ,theirspatialstructurerepresentkeyfactors inanalyzingpopulationdiversitybecausetheygiveanindicationoflikelihoodofmovementoforganisms betweenpopulationsandsubsequentgeneticanddemographicinterchange.Similarly,anestimateofthe overallpopulationsizeprovidesameasureofthepotentialgeneticdiversitywithinthepopulation;large populationsusuallyrepresentlargergenepoolsandhencegreaterpotentialdiversityseeGeneticdiversity 2 Isolatedpopulations,withverylowlevelsofinterchange,showhighlevelsofgeneticdivergence Hunter, 2002:145 [42],andexhibituniqueadaptationstothebioticandabioticcharacteristicsoftheirhabitat.The geneticdiversityofsomegroupsthatgenerallydonotdispersewell-suchasamphibians,mollusks,and someherbaceousplants-maybemostlyrestrictedtolocalpopulations Avise,1994 [4].Forthisreason, rangeretractionsofspeciescanleadtolossoflocalpopulationsandthegeneticdiversitytheyhold.Lossof isolatedpopulationsalongwiththeiruniquecomponentofgeneticvariationisconsideredbysomescientists tobeoneofthegreatestbutmostoverlookedtragediesofthebiodiversitycrisis Ehrlich&Raven1969 [23]. Populationscanbecategorizedaccordingtothelevelofdivergencebetweenthem.Isolatedandgenetically distinctpopulationsofasinglespeciesmaybereferredtoassubspeciesaccordingtosomebutnotallspecies concepts.Populationsthatshowlessgeneticdivergencemightberecognizedas variants or races. However, thedistinctionsbetweensubspeciesandothercategoriescanbesomewhatarbitraryseeSpeciesdiversity Chapter6. Aspeciesthatisecologicallylinkedtoaspecialized,patchyhabitatmaylikelyassumethepatchydistributionofthehabitatitself,withseveraldierentpopulationsdistributedatdierentdistancesfromeach other.Thisisthecase,forexample,forspeciesthatliveinwetlands,alpinezonesonmountaintops,particularsoiltypesorforesttypes,springs,andmanyothercomparablesituations.Individualorganismsmay 1 Thiscontentisavailableonlineat PAGE 48 42 CHAPTER12.POPULATIONDIVERSITY periodicallydispersefromonepopulationtoanother,facilitatinggeneticexchangebetweenthepopulations. Thisgroupofdierentbutinterlinkedpopulations,witheachdierentpopulationlocatedinitsown,discrete patchofhabitat,iscalleda metapopulation Theremaybequitedierentlevelsofdispersalbetweentheconstituentpopulationsofametapopulation. Forexample,alargeorovercrowdedpopulationpatchisunlikelytobeabletosupportmuchimmigration fromneighboringpopulations;itcan,however,actasa source ofdispersingindividualsthatwillmoveaway tojoinotherpopulationsorcreatenewones.Incontrast,asmallpopulationisunlikelytohaveahigh degreeofemigration;instead,itcanreceiveahighdegreeofimmigration.Apopulationthatrequiresnet immigrationinordertosustainitselfactsasa sink .Theextentofgeneticexchangebetweensourceand sinkpopulationsdepends,therefore,onthesizeofthepopulations,thecarryingcapacityofthehabitats wherethepopulationsarefound,andtheabilityofindividualstomovebetweenhabitats.Consequently, understandinghowthepatchesandtheirconstituentpopulationsarearrangedwithinthemetapopulation, andtheeasewithwhichindividualsareabletomoveamongthemiskeytodescribingthepopulationdiversity andconservingthespecies.Formorediscussion,seethemoduleonMetapopulations. PAGE 49 Chapter13 BiogeographicDiversity 1 Biogeography is"thestudyofthedistributionoforganismsinspaceandthroughtime".Analysesof thepatternsofbiogeographycanbedividedintothetwoeldsofhistoricalbiogeographyandecological biogeography Wiley,1981 [109]. Historicalbiogeography examinespasteventsinthegeologicalhistoryoftheEarthandusestheseto explainpatternsinthespatialandtemporaldistributionsoforganismsusuallyspeciesorhighertaxonomic ranks.Forexample,anexplanationofthedistributionofcloselyrelatedgroupsoforganismsinAfrica andSouthAmericaisbasedontheunderstandingthatthesetwolandmasseswereformerlyconnected aspartofasinglelandmassGondwana.Theancestorsofthoserelatedspecieswhicharenowfound inAfricaandSouthAmericaareassumedtohavehadacosmopolitandistributionacrossbothcontinents whentheywereconnected.Followingtheseparationofthecontinentsbytheprocessofplatetectonics, theisolatedpopulationsareassumedtohaveundergone allopatricspeciation i.e. ,speciationachieved betweenpopulationsthatarecompletelygeographicallyseparate.Thisseparationresultedintheclosely relatedgroupsofspeciesonthenowseparatecontinents.Clearly,anunderstandingofthesystematicsof thegroupsoforganisms i.e. ,theevolutionaryrelationshipsthatexistsbetweenthespeciesisanintegral partofthesehistoricalbiogeographicanalyses. Thesamehistoricalbiogeographichypothesescanbeappliedtothespatialandtemporaldistributions ofmarinebiota.Forexample,thebiogeographyofshesfromdierentoceanbasinshasbeenshownto beassociatedwiththegeologicalevolutionoftheseoceanbasinssee StiassnyandHarrison,2000 [95]for exampleswithreferences.However,wecannotassumethatallexistingdistributionpatternsaresolelythe productofthesepastgeologicalprocesses.Itisevident,forexample,thattheexistingmarinefaunaofthe Mediterraneanisaproductofthecomplexgeologicalhistoryofthismarinebasin,involvingseparationfrom theIndianandAtlanticOceans,periodsofextensivedesiccationfollowedbyoodingandrecolonizationfrom theAtlantic Por,1989 [76].However,thereisalsogoodevidencethattheeasternendoftheMediterranean hasbeencolonizedmorerecentlybyspeciesthathavedispersedfromtheRedSeaviatheSuezcanal. Thus,theeldof ecologicalbiogeography rstexaminesthedispersaloforganismsusuallyindividuals orpopulationsandthemechanismsthatinuencethisdispersal,andthenusesthisinformationtoexplain thespatialdistributionpatternsoftheseorganisms.Forfurtherdiscussionseethemoduleon"Biogeography" andsee Wiley,1981 [109],and HumphriesandParenti,1999 [39]. 1 Thiscontentisavailableonlineat PAGE 50 44 CHAPTER13.BIOGEOGRAPHICDIVERSITY PAGE 51 Chapter14 CommunityDiversity 1 A community comprisesthepopulationsofdierentspeciesthatnaturallyoccurandinteractinaparticular environment.Somecommunitiesarerelativelysmallinscaleandmayhavewell-denedboundaries.Some examplesare:speciesfoundinoraroundadesertspring,thecollectionofspeciesassociatedwithripening gsinatropicalforest,thoseclusteredaroundahydrothermalventontheoceanoor,thoseinthespray zoneofawaterfall,orunderwarmstonesinthealpinezoneonamountaintop.Othercommunitiesare larger,morecomplex,andmaybelessclearlydened,suchasold-growthforestsofthenorthwestcoastof NorthAmerica,lowlandfencommunitiesoftheBritishIsles,orthecommunityoffreshwaterspeciesofLake Baikal. Sometimesbiologistsapplytheterm"community"toasubsetoforganismswithinalargercommunity. Forexample,somebiologistsmayrefertothe"community"ofspeciesspecializedforlivingandfeeding entirelyintheforestcanopy,whereasotherbiologistsmayrefertothisaspartofalargerforestcommunity. Thislargerforestcommunityincludesthosespecieslivinginthecanopy,thoseontheforestoor,andthose movingbetweenthesetwohabitats,aswellasthefunctionalinterrelationshipsbetweenallofthese.Similarly, somebiologistsworkingonecosystemmanagementmightdistinguishbetweenthecommunityofspeciesthat areendemictoanarea e.g. speciesthatareendemictoanislandaswellasthose"exotic"speciesthat havebeenintroducedtothatarea.Theintroducedspeciesformpartofthelarger,modiedcommunityof thearea,butmightnotbeconsideredaspartoftheregionsoriginalanddistinctivecommunity. Communitiesarefrequentlyclassiedbytheiroverallappearance,or physiognomy .Forexample,coral reefcommunitiesareclassiedaccordingtotheappearanceofthereefswheretheyarelocated, i.e. ,fringing reefcommunities,barrierreefcommunities,andatollcommunities.Similarly,dierentstreamcommunities maybeclassiedbythephysicalcharacteristicsofthatpartofthestreamwherethecommunityislocated, suchasriezonecommunitiesandpoolcommunities.However,oneoftheeasiest,andhencemostfrequent methodsofcommunityclassicationisbasedonthedominanttypesofspeciespresentforexample,intertidal musselbedcommunities,PonderosapineforestcommunitiesofthePacicnorthwestregionoftheU.S.,or Mediterraneanscrublandcommunities.Multivariatestatisticsprovidemorecomplexmethodsfordiagnosing communities,forexample,byarrangingspeciesoncoordinateaxes e.g. ,x-yaxesthatrepresentgradientsin environmentalfactorssuchastemperatureorhumidity.Formoreinformation,seethemoduleon"Natural communitiesinspaceandtime." Thefactorsthatdeterminethediversityofacommunityareextremelycomplex.Therearemanytheories onwhatthesefactorsareandhowtheydeterminecommunityandecosystemdiversity.Environmental factors,suchastemperature,precipitation,sunlight,andtheavailabilityofinorganicandorganicnutrients areveryimportantinshapingcommunitiesand ecosystems Hunter:81 [43]notesthat,generally speaking,organismscanpersistandevolveinplaceswheretherearesucientenvironmentalresourcesforthe organismstochannelenergyintogrowthandreproductionratherthansimplythemetabolicrequirements forsurvival.Inotherwords,organismsarelesslikelytothriveinaharshenvironmentwithlowenergy 1 Thiscontentisavailableonlineat PAGE 52 46 CHAPTER14.COMMUNITYDIVERSITY resources.Onewayofmeasuringcommunitydiversityistoexaminetheenergyowthroughfoodwebsthat unitethespecieswithinthecommunity;theextentofcommunitydiversitycanbemeasuredbythenumber oflinksinthefoodweb.However,inpractice,itcanbeverydiculttoquantifythefunctionalinteractions betweenthespecieswithinacommunity.Itiseasiertomeasurethegeneticdiversityofthepopulationsin thecommunity,andtocountthenumbersofspeciespresent,andusethesemeasuresofgeneticdiversity andspeciesrichnessasproxiesfordescribingthefunctionaldiversityofthecommunity.Theevolutionary ortaxonomicdiversityofthespeciespresentisanotherwayofmeasuringthediversityofacommunity,for applicationtoconservationbiology. PAGE 53 Chapter15 Ecoregions 1 Sincethe1980s,therehasbeenanincreasingtendencytomapbiodiversityover"ecosystemregions"or "ecoregions".An ecoregion is"arelativelylargeunitoflandorwatercontainingageographicallydistinct assemblageofspecies,naturalcommunities,andenvironmentalconditions" WWF,1999 [28];thus,the ecosystemswithinanecoregionhavecertaindistinctcharactersincommon Bailey,1998a [6].Several standardmethodsofclassifyingecoregionshavebeendeveloped,withclimate,altitude,andpredominant vegetationbeingimportantcriteria Steinetal.,2000 [93].Bailey's,1998a,bclassicationisone ofthemostwidelyadopted.Itisahierarchicalsystemwithfourlevels:domains,divisions,provincesand sections. Domainsarethelargestgeographiclevelsandaredenedbyclimate, e.g. ,polardomain,drydomain, orhumidtropicaldomain.Domainsaresplitintosmallerdivisionsthataredenedaccordingclimate andvegetation,andthedivisionsaresplitintosmallerprovincesthatareusuallydenedbytheirmajor plantformations.Somedivisionsalsoincludevarietiesof"mountainprovinces".Thesegenerallyhavea similarclimaticregimetotheneighboringlowlandsbutshowsomealtitudinalzonation,andtheyaredened accordingtothetypesofzonationpresent.Provincesaredividedintosections,whicharedenedbythe landformspresent. Becauseecoregionsaredenedbytheirsharedbioticandabioticcharacteristics,theyrepresentpractical unitsonwhichtobaseconservationplanning.Moreover,thehierarchicalnatureofBailey'secoregionclassicationallowsforconservationmanagementtobeplannedandimplementedatavarietyofgeographicallevels, fromsmallscaleprogramsfocusedondiscretesections,tomuchlargernationalorinternationalprojectsthat targetdivisions.OlsonandDinerstein 2002 [72]identied238terrestrialoraquaticecoregionscalledthe "Global200"thattheyconsideredtobeprioritiesforglobalconservation.Theseecoregionswereselected becausetheyharborexceptionalbiodiversityandarerepresentativeofthevarietyofEarthsecosystems. ForfurtherdiscussionofecoregionsseethemodulesonLandscapeecologyandConservationplanningona regionalscale. 1 Thiscontentisavailableonlineat PAGE 54 48 CHAPTER15.ECOREGIONS PAGE 55 Chapter16 Extinction 1 Extinction thecompletedisappearanceofaspeciesfromEarthisanimportantpartoftheevolutionof lifeonEarth.Thecurrentdiversityofspeciesisaproductoftheprocessesofextinctionandspeciation throughouttheprevious3.8billionyearhistoryoflife.Raup 1991 [78]assumedthattheremightbe40 millionspeciesalivetoday,butbetween5and50billionspecieshavelivedatsometimeduringthehistoryof theEarth.Therefore,Raupestimatedthat99.9%ofallthelifethathasexistedonEarthisnow extinct ;a speciesisassumedtobeextinctwhenthereisnoreasonabledoubtthatthelastindividualhasdied IUCN, 2002 [29].However,extinctionhasnotoccurredataconstantpacethroughtheEarth'shistory.Therehave beenatleastveperiodswhentherehasbeenasuddenincreaseintherateofextinction,suchthattherate hasatleastdoubled,andtheextinctionshaveincludedrepresentativesfrommanydierenttaxonomicgroups ofplantsandanimals;theseeventsarecalled massextinctions .Thetimingofthesemassextinctionsis showninFigure16.1. 1 Thiscontentisavailableonlineat PAGE 56 50 CHAPTER16.EXTINCTION Figure16.1 EachoftherstvemassextinctionsshowninFigure16.1representsasignicantlossofbiodiversitybutrecoveryhasbeengoodonageologictimescale.Massextinctionsareapparentlyfollowedbyasudden burstofevolutionarydiversicationonthepartoftheremainingspecies,presumablybecausethesurviving speciesstartedusinghabitatsandresourcesthatwerepreviously"occupied"bymorecompetitivelysuccessful speciesthatwentextinct.However,thisdoesnotmeanthattherecoveriesfrommassextinctionhavebeen rapid;theyhaveusuallyrequiredsometensofmillionsofyears Jablonski,1995 [49]. Itishypothesizedthatwearecurrentlyonthebrinkofa"sixthmassextinction,"butonethatdiers frompreviousevents.Theveothermassextinctionspredatedhumansandwereprobablytheultimate productsofsomephysicalprocess e.g. climatechangethroughmeteorimpacts,ratherthanthedirect consequenceoftheactionofsomeotherspecies.Incontrast,thesixthmassextinctionistheproductof humanactivityoverthelastseveralhundred,orevenseveralthousandyears.Thesemassextinctions,and theirhistoricandmodernconsequencesarediscussedinmoredetailinthemodulesonHistoricalperspectives onextinctionandthecurrentbiodiversitycrisis,andEcologicalconsequencesofextinctions.. PAGE 57 Chapter17 LandscapeDiversity 1 A landscape is"amosaicofheterogeneouslandforms,vegetationtypes,andlanduses" Urbanetal., 1987 [101].Therefore,assemblagesofdierentecosystemsthephysicalenvironmentsandthespeciesthat inhabitthem,includinghumanscreatelandscapesonEarth.Althoughthereisnostandarddenitionof thesizeofalandscape,theyareusuallyinthehundredorthousandsofsquaremiles. Speciescompositionandpopulationviabilityareoftenaectedbythestructureofthelandscape;for example,thesize,shape,andconnectivityofindividualpatchesofecosystemswithinthelandscape Noss, 1990 [71].Conservationmanagementshouldbedirectedatwholelandscapestoensurethesurvivalof speciesthatrangewidelyacrossdierentecosystems e.g. ,jaguars,quetzals,speciesofplantsthathave widelydispersedpollenandseeds Hunter,2002:83-85,268-270[42] Diversitywithinandbetweenlandscapesdependsonlocalandregionalvariationsinenvironmentalconditions,aswellasthespeciessupportedbythoseenvironments.Landscapediversityisoftenincorporated intodescriptions"ecoregionsChapter15," 1 Thiscontentisavailableonlineat PAGE 58 52 CHAPTER17.LANDSCAPEDIVERSITY PAGE 59 Chapter18 EcologicalValue 1 Naturalcommunitiesarenely-tunedsystems,whereeachspecieshasan ecologicalvalue totheother speciesthatarepartofthatecosystem.Speciesdiversityincreasesanecosystem'sstabilityandresilience,in particularitsabilitytoadaptandrespondtochangingenvironmentalconditions.Ifacertainamount,ortype suchasakeystonespeciesofspeciesarelost,eventuallyitleadstothelossofecosystemfunction.Many ecosystemsthoughhavebuilt-inredundanciessothattwoormorespecies'functionsmayoverlap.Becauseof theseredundancies,severalchangesinthenumberortypeofspeciesmaynotimpactanecosystem.However, notallspecieswithinanecosystemareofthesameimportance.Speciesthatareimportantduetotheirsheer numbersareoftencalled dominantspecies .Thesespeciesmakeupthemostbiomassofanecosystem. Speciesthathaveimportantecologicalrolesthataregreaterthanonewouldexpectbasedontheirabundance arecalled keystonespecies .Thesespeciesareoftencentraltothestructureofanecosystem,removalof oneorseveralkeystonespeciesmayhaveconsequencesimmediately,ordecadesorcenturieslater Jacksonet al.2001 [ ? ].Ecosystemsarecomplexanddiculttostudy,thusitisoftendiculttopredictwhichspecies arekeystonespecies.Theimpactofremovinganindividualorseveralkeystonespeciesfromkelpforestsin thePacicisexaminedinExample18.1NorthernPacicKelpForests. Example18.1:NorthernPacicKelpForests Kelpforests,astheirnamesuggests,aredominatedbykelp,abrownseaweedofthefamily Laminariales.Theyarefoundinshallow,rockyhabitatsfromtemperatetosubarcticregions,and areimportantecosystemsformanycommerciallyvaluableshandinvertebrates. VastforestsofkelpandothermarineplantsexistedinthenorthernPacicOceanpriortothe 18thcentury.ThekelpwaseatenbyherbivoressuchasseaurchinsFamilyStrongylocentrotidae, whichinturnwerepreyeduponbypredatorssuchasseaotters Enhydralutris .Huntingduring the18thand19thcenturiesbroughtseaotterstothebrinkofextinction.Intheabsenceofsea otters,seaurchinpopulationsburgeonedandgrazeddownthekelpforests,attheextremecreating "urchinbarrens,"wherethekelpwascompletelyeradicated.Otherspeciesdependentonkelp suchasredabalone Haliotisrufescens wereaectedtoo.Legalprotectionofseaottersinthe20th centuryledtopartialrecoveryofthesystem. MorerecentlyseaotterpopulationsinAlaskaseemtobethreatenedbyincreasedpredation fromkillerwhales Orcinusorca Estesetal.1998 [ ? ].Itappearsthatwhalesmayhaveshifted theirdiettoseaotterswhenpopulationsoftheirpreferredprey,Stellarsealions Arctocephalus townsendi andHarborseals Phocavitulina declined.Theexactreasonforthedeclineinthe sealionandsealpopulationsisstillunclear,butappearstobeduetodeclinesintheirpreyin combinationwithincreasedshingandhigheroceantemperatures.Asaresultofthelossofsea otters,increasedseaurchinpopulationsaregrazingdownkelpbedsagain. 1 Thiscontentisavailableonlineat PAGE 60 54 CHAPTER18.ECOLOGICALVALUE Example18.2:SouthernCalifornianKelpForests Interestingly,asimilarscenarioinkelpforestsinSouthernCaliforniadidnotshowimmediate eectsafterthedisappearanceofseaottersfromtheecosystem.Thisisbecausethesystemwas morediverseinitially.OtherpredatorsCaliforniasheepheadsh, Semicossyphuspulcher ,andspiny lobsters, Panulirusinterruptus andcompetitorsabalone Haliotisspp oftheseaurchinhelped maintainthesystem.However,whenthesepredatorsandcompetitorswereover-harvestedaswell inthe1950s,thekelpforestsdeclineddrasticallyasseaurchinpopulationsboomed. Inthe1970sand1980s,aseaurchinsherydevelopedwhichthenenabledthekelpforestto recover.However,itleftasystemwithlittlediversity.Theinterrelationshipsamongthesespecies andthechangesthatreverberatethroughsystemsasspeciesareremovedaremirroredinother ecosystemsontheplanet,bothaquaticandterrestrial. Asthisexampleillustrates,biodiversityisincrediblycomplexandconservationeortscannot focusonjustonespeciesorevenoneventsoftherecentpast. PAGE 61 GLOSSARY 55 Glossary A albedo theamountofsolarradiationreectedby asurface allopatricspeciation speciationachievedbetweenpopulations thatarecompletelygeographically separatedtheirrangesdonotoverlapor arenotcontiguous. Alphadiversity thediversitywithinaparticularareaor ecosystem;usuallyexpressedbythe numberofspecies i.e. ,speciesrichness inthatecosystem Areaofendemism anareaswhichhasahighproportionof endemicspecies i.e. ,specieswith distributionsthatarenaturallyrestricted tothatregion B bequestvalue thevalueofknowingsomethingwillbe thereforfuturegenerations Betadiversity acomparisonofofdiversitybetween ecosystems,usuallymeasuredasthe amountofspecieschangebetweenthe ecosystems Biodiversitycoldspots areasthathaverelativelylowbiological diversitybutarealsoexperiencingahigh rateofhabitatloss Biodiversityhotspots ingeneraltermstheseareareasthathave highlevelsofendemismandhence diversitybutwhicharealsoexperiencing ahighrateoflossofhabitat.This conceptwasoriginallydevelopedfor terrestrialecosystems.Aterrestrial biodiversityhotspotisanareathathas atleast0.5%,or1,500oftheworldsca. 300,000speciesofgreenplants Viridiplantae ,andthathaslostatleast 70%ofitsprimaryvegetation Myerset al.,2000 [ ? ].Marinebiodiversity hotspotshavebeendenedforcoralreefs, basedonmeasurementsofrelative endemismofmultipletaxaspeciesof corals,snails,lobsters,sheswithina regionandtherelativelevelofthreatto thatregion Robertsetal.,2002 [ ? ] Biodiversity thevarietyoflifeonEarthatallits levels,fromgenestoecosystems,andthe ecologicalandevolutionaryprocessesthat sustainit biogeography thestudyofthedistributionoforganisms inspaceandthroughtime Biologicalspeciesconcept aspeciesisagroupofinterbreeding naturalpopulationsunableto successfullymateorreproducewithother suchgroups,andwhichoccupiesa specicnicheinnatureMayr,1982; BisbyandCoddington,1995. C Community thepopulationsofdierentspeciesthat naturallyoccurandinteractina particularenvironment Community thepopulationsofdierentspeciesthat naturallyoccurandinteractina particularenvironment. D Demography thestatisticalcharacteristicsofthe populationsuchassize,density,birth anddeathrates,distribution,and movementormigration. directusevalue PAGE 62 56 GLOSSARY referstoproductsorgoodswhichare consumeddirectlysuchasfoodortimber dominantspecies speciesthatareimportantduetotheir sheernumbersinanecosystem E Ecologicalbiogeography: thestudyofthedispersaloforganisms usuallyindividualsorpopulationsand themechanismsthatinuencethis dispersal,andtheuseofthisinformation toexplainspatialdistributionpatterns ecologicalvalue thevaluesthateachspecieshasaspartof anecosystem Ecoregion arelativelylargeunitoflandorwater containingageographicallydistinct assemblageofspecies,natural communites,andenvironmental conditions WWF,1999 [ ? ] Ecoregions arelativelylargeunitoflandorwater containingageographicallydistinct assemblageofspecies,natural communities,andenvironmental conditions WWF,1999 [ ? ].The ecosystemswithinanecoregionhave certaindistinctcharactersincommon Bailey,1998a [ ? ]. Ecosystem acommunityplusthephysical environmentthatitoccupiesatagiven time ecosystem acommunityplusthephysical environmentthatitoccupiesatagiven time. Ecosystem Endemicspecies thosespecieswhosedistributionsare naturallyrestrictedtoadenedregion evapotranspiration istheprocesswherebywaterisabsorbed fromsoilbyvegetationandthenreleased backintotheatmosphere Evolutionarysignicantunit agroupoforganismsthathasundergone signicantgeneticdivergencefromother groupsofthesamespecies.Identication ofESUsisbasedonnaturalhistory information,rangeanddistributiondata, andresultsfromanalysesof morphometrics,cytogenetics,allozymes andnuclearandmitochondrialDNA. Concordanceofthosedata,andthe indicationofsignicantgeneticdistance betweensympatricgroupsoforganisms, arecriticalforestablishinganESU. existencevalue thevalueofknowingsomethingexistseven ifyouwillneveruseitorseeit Extinct aspeciesisassumedtobeextinctwhen thereisnoreasonabledoubtthatthelast individualhasdied IUCN,2002 [ ? ] Extinction thecompletedisappearanceofaspecies fromEarth G Gammadiversity ameasureoftheoveralldiversitywithina largeregion.Geographic-scalespecies diversityaccordingto Hunter02:448 [42] GeneticDiversity referstoanyvariationinthenucleotides, genes,chromosomes,orwholegenomesof organisms. H Historicalbiogeography thestudyofeventsinthegeological historyoftheEarthandtheiruseto explainpatternsinthespatialand temporaldistributionsoforganisms usuallyspeciesorhighertaxonomic ranks I indirectusevalue referstotheservicesthatsupportthe productsthatareconsumed,thisincludes ecosystemsfunctionslikenutrientcycling K keystonespecies PAGE 63 GLOSSARY 57 speciesthathaveimportantecological rolesthataregreaterthanonewould expectbasedontheirabundance L Landscape amosaicofheterogeneouslandforms, vegetationtypes,andlanduses Urbanet al.,1987 [ ? ] Landscapes amosaicofheterogeneouslandforms, vegetationtypes,andlanduses Urbanet al.,1987 [ ? ]. M MarineBiodiversityhotspots Massextinction aperiodwhenthereisasuddenincrease intherateofextinction,suchthatthe rateatleastdoubles,andtheextinctions includerepresentativesfrommany dierenttaxonomicgroupsofplantsand animals Metapopulation agroupofdierentbutinterlinked populations,witheachdierent populationlocatedinitsown,discrete patchofhabitat Morphologicalspeciesconcept speciesarethesmallestnatural populationspermanentlyseparatedfrom eachotherbyadistinctdiscontinuityin theseriesofbiotypeDuRietz,1930; BisbyandCoddington,1995. N nonuseorpassivevalue referstothevalueforthingsthatwedon't usebutwouldfeelalossiftheywereto disappear O Orobiome amountainousenvironmentorlandscape withitsconstituentecosystems Orogenesis theprocessofmountainbuilding. P Parapatric occupyingcontiguousbutnotoverlapping ranges. Photosynthesis theformationofcarbohydratesfrom carbondioxideandwater,throughthe actionoflightenergyonalight-sensitive pigment,suchaschlorophyll,andusually resultingintheproductionofoxygen Phylogeneticdiversity theevolutionaryrelatednessofthespecies presentinanarea. Phylogeneticspeciesconcept aspeciesisthesmallestgroupof organismsthatisdiagnosably[thatis, identiably]distinctfromothersuch clustersandwithinwhichthereisa parentalpatternofancestryanddescent Cracraft,1983;BisbyandCoddington, 1995. PlateTectonics theforcesactingonthelarge,mobile piecesor"plates"oftheEarth's lithospheretheupperpartofthemantle andcrustoftheEarthwheretherocks arerigidcomparedtothosedeeperbelow theEarth'ssurfaceandthemovementof those"plates". Population 1.agroupofindividualsofthesamespecies thatshareaspectsoftheirdemographyor geneticsmorecloselywitheachother thanwithothergroupsofindividualsof thatspecies 2.Apopulationmayalsobedenedasa groupofindividualsofthesamespecies occupyingadenedareaatthesame time Hunter,2002:144 [ ? ] potentialoroptionvalue referstotheusethatsomethingmayhave inthefuture S Sink apopulationpatch,inametpopulation thatdoesnothaveahighdegreeof emigrationoutsideitsboundariesbut, instead,requiresnetimmigrationinorder tosustainitself Source PAGE 64 58 GLOSSARY apopulationpatch,inametapopulation, fromwhichindividualsdispersetoother populationpatchesorcreatenewones Speciesdiversity thenumberofdierentspeciesina particulararea i.e. ,speciesrichness weightedbysomemeasureofabundance suchasnumberofindividualsorbiomass. Speciesevenness therelativeabundancewithwhicheach speciesarerepresentedinanarea. 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[103]N.F.MeierR.vanLoonE.M.vanHoveW.B.J.T.GiesenG.vanderVeldeVanKatwijk,M.N. andC.denHartog.Sabakiriversedimentloadandcoralstress:correlationbetweensedimentsand conditionofthemalindi-watamureefsinkenyaindianocean. MarineBiology ,117:439,1993. [104]L.VanValen.Thehistoryandstabilityofatmosphericoxygen. Science ,171:439,1971. [105]H.Walter. VegetationoftheEarthandecologicalsystemsofthegeo-biosphere .Springer-Verlag,New York,NewYork,U.S.A.,third,revisedandenlargededitionedition,1985.translatedfromthefth, revisedGermaneditionbyOwenMuise. [106]H.Walter. VegetationoftheEarthandecologicalsystemsofthegeo-biosphere .Springer-Verlag,New York,NewYork,U.S.A.,third,revisedandenlargededitionedition,1985.translatedfromthefth, revisedGermaneditionbyOwenMuise. PAGE 71 BIBLIOGRAPHY 65 [107]D.G.WennyandD.J.Levy.Directedseecdispercalbybellbirdsinatorpicalcloudforest. Proceedings oftheNationalAcademyofSciences ,95:6204,1998. [108]R.H.Whittaker.Evolutionandmeasurementofspeciesdiversity. Taxon ,21:213,1972. [109]E.O.Wiley. Phylogenetics:thetheoryandpracticeofphylogeneticsystematics .JohnWileyandSons, NewYork,NewYork,U.S.A,1981. [110]P.H.WilliamsandC.J.Humphries.Comparingcharacterdiversityamongbiotas.InK.J.Gaston, editor, Biodiversity:abiologyofnumbersanddierence ,pages54.BlackwellScienceLtd.,Oxford, U.K.,1996. [111]M.C.WitmerandA.S.Cheke.Thedodoandthetambalacoquetree:anobligatemutualismreconsidered. Oikos ,61:133,1991. PAGE 72 66 INDEX IndexofKeywordsandTerms Keywords arelistedbythesectionwiththatkeywordpagenumbersareinparentheses.Keywords donotnecessarilyappearinthetextofthepage.Theyaremerelyassociatedwiththatsection. Ex. apples,1.1 Terms arereferencedbythepagetheyappearon. Ex. apples,1 A albedo,2 allopatricspeciation,43 Alphadiversity,31 B bequestvalue,33 betadiversity,31 biodiversity,2,5,5,3,4,5, 6,7,10,11,12, 13,1445,15,16,17 biodiversitycoldspots,8 biodiversityhotspots,7 Biogeography,43 biologicalspeciesconcept,26 C collector'scurve,15 communities,9 community,45 D demography,41 directusevalue,33 dominantspecies,53 E E,25 ecologicalbiogeography,43 ecologicalvalue,53 ecoregion,47 ecoregions,9 ecosystem,25,39 ecosystems,7,9,31,45 endemicspecies,7 evapotranspiration,2,2 evolutionarysignicantunit,26 existencevalue,33 extinct,49 Extinction,49 G Gammadiversity,31 geneticdiversity,9 H H,25 Historicalbiogeography,43 I incipientspecies,26 indirectusevalue,33 K keystonespecies,53 L landscape,51 landscapes,9 M Marinebiodiversityhotspots,8 massextinctions,49 metapopulation,42 morphologicalspeciesconcept,26,26 N non-useorpassivevalues,33 O orobiomes,7 orogenesis,5 P parapatric,26 Photosynthesis,37 phylogeneticdiversity,25 phylogeneticspeciesconcept,26 physiognomy,45 platetectonics,5 population,41,41 populationdiversity,9 PotentialorOptionvalue,33 R races.,41 radiationbalance,2 S sink,42 source,42 speciesdiversity,9,25 speciesevenness,25 speciesrichness,7,25,31 surfaceroughness,2,2 sympatric,26 T terrestrialbiodiversityhotspot,7 V variants,41 W watersheds,2 wetlands,3 PAGE 73 ATTRIBUTIONS 67 Attributions Collection: WhatisBiodiversity Editedby:NoraBynum URL:http://cnx.org/content/col10639/1.1/ License:http://creativecommons.org/licenses/by/3.0/ Module:"GlobalProcesses" By:MelinaLaverty,EleanorSterling URL:http://cnx.org/content/m12159/1.1/ Pages:1-4 Copyright:MelinaLaverty,EleanorSterling License:http://creativecommons.org/licenses/by/1.0 Module:"DenitionofBiodiversity" By:IanHarrison,MelinaLaverty,EleanorSterling URL:http://cnx.org/content/m12151/1.2/ Pages:5-6 Copyright:IanHarrison,MelinaLaverty,EleanorSterling License:http://creativecommons.org/licenses/by/1.0 Module:"SpatialGradientsinBiodiversity" By:IanHarrison,MelinaLaverty,EleanorSterling URL:http://cnx.org/content/m12173/1.2/ Pages:7-8 Copyright:IanHarrison,MelinaLaverty,EleanorSterling License:http://creativecommons.org/licenses/by/1.0 Module:"IntroductiontotheBiodiversityHierarchy" By:IanHarrison,MelinaLaverty,EleanorSterling URL:http://cnx.org/content/m12162/1.2/ Page:9 Copyright:IanHarrison,MelinaLaverty,EleanorSterling License:http://creativecommons.org/licenses/by/1.0 Module:"WhatisBiodiversity?Acomparisonofspidercommunities" By:JamesGibbs URL:http://cnx.org/content/m12179/1.1/ Pages:11-24 Copyright:JamesGibbs License:http://creativecommons.org/licenses/by/1.0 Module:"SpeciesDiversity" By:IanHarrison,MelinaLaverty,EleanorSterling URL:http://cnx.org/content/m12174/1.3/ Pages:25-29 Copyright:IanHarrison,MelinaLaverty,EleanorSterling License:http://creativecommons.org/licenses/by/1.0 PAGE 74 68 ATTRIBUTIONS Module:"Alpha,Beta,andGammaDiversity" By:IanHarrison,MelinaLaverty,EleanorSterling URL:http://cnx.org/content/m12147/1.2/ Pages:31-32 Copyright:IanHarrison,MelinaLaverty,EleanorSterling License:http://creativecommons.org/licenses/by/1.0 Module:"IntroductiontoUtilitarianValuationofBiodiversity" By:MelinaLaverty,EleanorSterling URL:http://cnx.org/content/m12164/1.2/ Pages:33-34 Copyright:MelinaLaverty,EleanorSterling License:http://creativecommons.org/licenses/by/1.0 Module:"BiodiversityoverTime" By:RobertAhlnger URL:http://cnx.org/content/m12148/1.2/ Page:35 Copyright:RobertAhlnger License:http://creativecommons.org/licenses/by/1.0 Module:"ABriefHistoryofLifeonEarth" By:IanHarrison,MelinaLaverty,EleanorSterling URL:http://cnx.org/content/m12146/1.2/ Pages:37-38 Copyright:IanHarrison,MelinaLaverty,EleanorSterling License:http://creativecommons.org/licenses/by/1.0 Module:"EcosystemDiversity" By:IanHarrison,MelinaLaverty,EleanorSterling URL:http://cnx.org/content/m12156/1.2/ Pages:39-40 Copyright:IanHarrison,MelinaLaverty,EleanorSterling License:http://creativecommons.org/licenses/by/1.0 Module:"PopulationDiversity" By:IanHarrison,MelinaLaverty,EleanorSterling URL:http://cnx.org/content/m12171/1.2/ Pages:41-42 Copyright:IanHarrison,MelinaLaverty,EleanorSterling License:http://creativecommons.org/licenses/by/1.0 Module:"BiogeographicDiversity" By:IanHarrison,MelinaLaverty,EleanorSterling URL:http://cnx.org/content/m12149/1.2/ Page:43 Copyright:IanHarrison,MelinaLaverty,EleanorSterling License:http://creativecommons.org/licenses/by/1.0 Module:"CommunityDiversity" By:IanHarrison,MelinaLaverty,EleanorSterling URL:http://cnx.org/content/m12150/1.2/ Pages:45-46 Copyright:IanHarrison,MelinaLaverty,EleanorSterling License:http://creativecommons.org/licenses/by/1.0 PAGE 75 ATTRIBUTIONS 69 Module:"Ecoregions" By:IanHarrison,MelinaLaverty,EleanorSterling URL:http://cnx.org/content/m12155/1.2/ Page:47 Copyright:IanHarrison,MelinaLaverty,EleanorSterling License:http://creativecommons.org/licenses/by/1.0 Module:"Extinction" By:IanHarrison,MelinaLaverty,EleanorSterling URL:http://cnx.org/content/m12157/1.2/ Pages:49-50 Copyright:IanHarrison,MelinaLaverty,EleanorSterling License:http://creativecommons.org/licenses/by/1.0 Module:"LandscapeDiversity" By:IanHarrison,MelinaLaverty,EleanorSterling URL:http://cnx.org/content/m12165/1.2/ Page:51 Copyright:IanHarrison,MelinaLaverty,EleanorSterling License:http://creativecommons.org/licenses/by/1.0 Module:"EcologicalValue" By:MelinaLaverty,EleanorSterling URL:http://cnx.org/content/m12154/1.2/ Pages:53-54 Copyright:MelinaLaverty,EleanorSterling License:http://creativecommons.org/licenses/by/1.0 PAGE 76 WhatisBiodiversity Thiscollectionprovidesanoverviewofwhatismeantbytheterm`biodiversity,'andhowwemeasureit. Thecollectionreviewsthedierentlevelsofbiodiversity,orthe`biodiversityhierarchy'including:genetic andphenotypicdiversity;populationdiversity;speciesdiversity;communitydiversity;ecosystemdiversity; landscapediversity;andhistoricalandecologicalbiogeographicdiversity.Briefdenitionsofpopulations, species,communities,andecosystemsareprovided,withsomeintroductorydiscussionofdierenttypes of`speciesconcepts.'Thecollectiondenestheterms`speciesrichness'and`speciesevenness'asmethods formeasuringspeciesdiversity,anditdiscussestheuseofspeciesrichnessasasurrogatefordescribing overallglobalbiodiversity.Thecollectionreviewsthedistributionofbiodiversityinspace,explainingthe denitionsofalpha,betaandgammadiversityformeasuringdiversitywithinandbetweenecosystems.The environmentalfactorsthataectthesepatternsofspatialdiversityarebrieydiscussed.Thecollectionalso includesabriefreviewofthedierentwaysbywhichassessmentsofspatialdiversityareusedforconservation planningandmanagemente.g.,basedonecoregions,orbiodiversityhotspotsandcoldspots.Thecollection concludeswithabriefdiscussionofdiversityovergeologicaltime. AboutConnexions Since1999,Connexionshasbeenpioneeringaglobalsystemwhereanyonecancreatecoursematerialsand makethemfullyaccessibleandeasilyreusablefreeofcharge.WeareaWeb-basedauthoring,teachingand learningenvironmentopentoanyoneinterestedineducation,includingstudents,teachers,professorsand lifelonglearners.Weconnectideasandfacilitateeducationalcommunities. Connexions'smodular,interactivecoursesareinuseworldwidebyuniversities,communitycolleges,K-12 schools,distancelearners,andlifelonglearners.Connexionsmaterialsareinmanylanguages,including English,Spanish,Chinese,Japanese,Italian,Vietnamese,French,Portuguese,andThai.Connexionsispart ofanexcitingnewinformationdistributionsystemthatallowsfor PrintonDemandBooks .Connexions haspartneredwithinnovativeon-demandpublisherQOOPtoacceleratethedeliveryofprintedcourse materialsandtextbooksintoclassroomsworldwideatlowerpricesthantraditionalacademicpublishers. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| MILLISECOND | CLASS.METHOD | MESSAGE |
|---|---|---|
| 0 | sobekcm_page_globals.constructor | |
| 0 | sobekcm_page_globals.constructor | Application State validated or built |
| 0 | sobekcm_database.verify_item_lookup_object | |
| 0 | sobekcm_page_globals.constructor | Navigation Object created from URI query string |
| 0 | sobekcm_database.verify_item_lookup_object | |
| 0 | sobekcm_page_globals.display_item | Retrieving item or group information |
| 0 | sobekcm_page_globals.get_entire_collection_hierarchy | Retrieving hierarchy information |
| 0 | sobekcm_assistant.get_entire_collection_hierarchy | |
| 0 | cached_data_manager.retrieve_item_aggregation | |
| 0 | cached_data_manager.retrieve_item_aggregation | Found item aggregation on local cache |
| 0 | item_aggregation_builder.get_item_aggregation | Found 'all' item aggregation in cache |
| 0 | system.web.ui.page.page_load (ufdc.page_load) | |
| 0 | sobekcm_page_globals.constructor.on_page_load | |
| 0 | html_echo_mainwriter.add_style_references | Adding style references to HTML |
| 0 | html_echo_mainwriter.add_text_to_page | Reading the text from the file and echoing back to the output stream |
| 42 | html_echo_mainwriter.add_text_to_page | Finished reading and writing the file |