According to the equilibrium model of island biogeography,thenumber of species on an island is determined by a balancebetweenspeciesimmigrationand extinctionTherate ofimmigration of newMeanwhile,the rate of speciesspecies to anisland decreases asextinction onthe islandthenumber of species on theincreases as the number ofislandincreases.speciespresentincreasesononaoonoImminigrationofnewspeciesNumber of speciespresent at equilibriumTotal numberof speciesinspeciespoolNumber of speciespresentFIGUREI9.8EccibOMacArthurand WilsEquilibrium model of island biogeography
Equilibrium model of island biogeography
The equilibrium model of island biogeography explained variation innumber of species on islands by the influences of isolation and areaon rates of immigration and extinction.The model predictedThe model predicted higherhigh rates of extinctionrates of immigration to islandson small islandsnearer a sourceof colonistsExtinction onImmigrationsmall islandsto nearislandsExtinction onlarge islandsImmigrationto farislandsS large,nearS small,farS small,nearS large, farNumberof speciesprcsentThe model also accountsThe model explains theforhighnumberof specieslownumberof specieson largc,near islands.on small,isolatedislands.Island distanceand areaand rates of immigrationandFGURE19.9extinction(datafromMacArthurandWilsonIgo3)
LARGE-SCALEECOLOGGEOGRAPHICECOOGISpecies Turnover on Islands
➢ Species Turnover on Islands
+10+10Numberofextinctions+10L5Numberofimmigrations+Aspredictedbytheequilibriummodel of island biogeographyconsiderablespeciesturnovertook110placeover this51-yearperiod10Santa Barbara30Santa Cruzkm-10San Miguel Los AngelesAnacapaSantaRosaSanta BarbaraCSantaSan Nicolas10+10Catalina8ASan ClementeSan+10Diego,+5+10Los Coronados109FTUJaredDiamond(1969)510CaliforniaChannelIslandsBirds,50ys,9islands,3~249km2,12~61km,FIGURE19.10Exinctionand immigrationofbird species on the California Channel Islandsberween1917and 1968 (data fronDiamond1969)
Jared Diamond(1969) California Channel Islands Birds, 50ys, 9 islands, 3~249km2 , 12~61km
LARGE-SCALEECOLOGGEOGRAPHICECOGIExperimental Island Biogeography
➢ Experimental Island Biogeography