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Ch13
BIOL100
• Biodiversity:sumtotalofallorganismsinanarea
• Splitintothreespecificlevels:
• Ecosystemdiversity
• Speciesdiversity
• GeneBcdiversity
• Speciesdiversity
• Numberorvarietyofspeciesinthe
worldorinaparBcularregion
• Speciesrichness
• Numberofspecies
• Evennessorrela4veabundance
• Extenttowhichnumbersof
individualsofdifferentspecies
areequalorskewed
• SpeciaBongeneratesnewspeciesandaddstospeciesrichness
• ExBncBonreducesspeciesrichness
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• Taxonomists
• ScienBstswhoclassifyspecies
• Commonancestry,abilitytointerbreed
• Genera
• Relatedspeciesaregroupedtogether
• Families
• Groupsofgenera
• Everyspecieshasatwo-partscienBficname
• Binomialnomenclature
• Genusandspecies
• Subspecies
• PopulaBonsofspeciesthatoccurindifferentareasanddifferslightlyfromeachother
• DivergencestopsshortofseparaBngthespecies
• OrsBllpotenBallyspeciaBng
• SubspeciesaredenotedwithathirdpartofthescienBficname
SiberianBger=Panthera)grisaltaica
BengalBger=Panthera)gris)gris
Allsubspeciesof)gershavedisappearedfrom93%oftheirhistoricrange
• Gene4cdiversityencompassesdifferencesinDNA
• AmongindividualswithinspeciesandpopulaBons
• IstherawmaterialforadaptaBontolocalcondiBons
• PopulaBonswithhighergeneBcdiversity
• Morelikelytosurvive
• Cancopewithenvironmentalchange
• PopulaBonswithlowgeneBcdiversity
• Morevulnerableto
• Environmentalchange
• Disease
• Inbreedingdepression:geneBcallysimilarparentsmateandproducelessfitoffspring
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• Ecosystemdiversity
• Numberandvarietyofecosystems
• AlsoencompassesdifferingcommuniBesandhabitats
• Sizes,shapes,andinterconnectednessofpatcheswithinhabitats,communiBes,orecosystems
• Speciesnotevenlydistributedamong
taxonomicgroups
• Manymoreinsects
• ~80%ofallspecies
• 40%ofallinsectsarebeetles
• Groupsaccumulatespeciesby:
• AdapBveradiaBon
• AllopatricspeciaBon
• LowratesofexBncBon
• Speciesrichness
• Goodgaugeforoverallbiodiversity
• EsBmatesof5–30millionspecieson
Earth
• Only1.7–2millionspecies
• HavebeenidenBfiedanddescribed
• VerydifficulttoidenBfyspecies
• Smallorganismsareeasilyoverlooked
• ManyspecieslookidenBcalunBl
closelyexamined
• ManyremotespotsonEarthremain
unexplored
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• Livingthings
• DistributedunevenlyacrossEarth
• La4tudinalgradient
• Speciesrichnessincreasestowardtheequator
• Equatorialregions
• HavehigherplantproducBvity
• Stableclimates
• NoglaciaBon
• Diversehabitatsincreaseniches
• Increasesspeciesdiversity
• Ecotone
• Areaswherehabitatsintermix
• Havehigherdiversityofniches
• Thereforehigherspeciesdiversity
• Ex4nc4on
• Occurswhenthelastmemberofaspeciesdies
• Speciesceasestoexist• Ex4rpa4on
• DisappearanceofaparBcularpopulaBonlocally
• NottheenBrespeciesglobally• CanleadtoexBncBon
• 99%ofallspecieseverexistedarenowexBnct
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• Past440millionyears
• MassexBncBonseliminatedatleast50%ofallspecies
• DinosaursexBnctatendoftheCretaceousperiod
• 65millionyearsago
• Madewayformammals
Ex)nc)onsfollowedhumanarrivalonislandsandcon)nents
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• TheRedList
• UpdatedlistofspeciesfacinghighrisksofexBncBons
• 22%ofmammalspecies
• 12%ofbirdspecies
• 16–86%ofallotherspecies
• Since1970
• 58fishspecies,9birdspecies,and2mammalspecieshavegone
exBnct
• WestAfricanblackrhinoceros,Baijiwhitedolphin(bothlast
decade)
• U.S.inthelast500years
• 236animaland17plantspeciesareconfirmedexBnct
• Actualnumbersareundoubtedlyhigher
http://www.iucnredlist.org/
• PopulaBonsaredeclining
• Withshrinkinggeographicranges
• GeneBc,ecosystem,andspecies
diversityarebeinglost
• LivingPlanetIndex
• summarizestrendsinpopulaBons
• Between1970and2003,theIndexfellby30%
• Reasonsforbiodiversitylosses
• MulBfaceted,complex,andhardtodetermine
• Fourprimarycauses
1. HabitatalteraBon2. Invasivespecies3. PolluBon4. OverharvesBng
• Globalclimatechangenowisthefihhcause
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• Greatestcauseofbiodiversityloss
• Farming
• Grazing
• Clearingforests
• Hydroelectricdams
• UrbanizaBonandsuburbansprawl
• Afewspecies(i.e.,pigeons,rats)benefitfromchanginghabitats
• generalists
Lessthan1%ofNorthAmerica’sGreatPlainsremains,andgrasslandbirdpopulaBonshavedeclined82–99%
• Forests
• Fragmentedbyroadsandlogging
• Smallforestfragments
• Losediversityfastest
• StarBngwithlargespecies
• Equilibriumtheoryofislandbiogeography
• DistribuBonofspeciesonoceanicislands
• ResultsfromanequilibriumbetweenimmigraBonand
exBrpaBon
• Predictsanisland’sspeciesrichness
• Basedontheisland’ssizeanddistancefromthemainland
• Alsoappliesto“habitatislands”
• Patchesofonehabitattypeisolatedwithina“sea”ofothers
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• Fewerspecies• Colonizeanislandfarfromthemainland
• Largeislands• HavehigherimmigraBonrates
• Largeislands• HavelowerexBncBonrates
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