1、ExtinctionPopulation extinction processFour general causes of extinction1.Environmental stochasticity2.Demographic stochasticity3.Abiotic catastrophes4.Lack genetic variationExtinctionEnvironmental stochasticityRandom,temporal variation:exogenous factor(s)Individuals experience same birth,death rate
2、s Temporal fluctuations,Between-generation scale Good,Bad Years=Generations:food abundanceSmall population&bad year ExtinctionExtinctionDemographic stochasticityRandom variation among individuals,Within-generation scaleNumber offspring,survivalIndividuals birth and death rates independent,hence can
3、differImportant small populations:chance extinctionExtinctionAbiotic(Physical)CatastrophesLarge,sudden density reductionEnvironmental,anthropogenicClimate changeTime scale relative to generation timeExtinctionGeneticLack variation,population fails to adaptRarest,but again global climate changeBehavi
4、or Population DynamicsVucetich et al.2019.Effects of social structure and prey dynamics on extinction risk in gray wolves.Conservation Biology 11:957.1.Wolves:social behavior-group,pack1 litter/year,dominant femaleamplify demographic stochasticity2.Prey availability:fluctuate,source of environmental
5、 stochasticityBehavior Population DynamicsGray wolf(Canis lupus)Isle Royale,MI;island in Lake SuperiorNational Park,500 mi2Wolves feed on mooseAbundance of old moose(9 yrs)keyBehavior Population DynamicsObjective:Simulate wolf population dynamicsPredict mean time to extinction(MTE)1.Age-dependent mo
6、rtality in wolves1/3 pups die first yearNo wolves older than 11 yrs2.Random litter size in wolves,Mean=1Behavior Population Dynamics3.Wolf packs:Some restructuring between yearsWhen prey abundance falls,smallest pack disperses,mortality costSurvivors join another packNumber packs proportional to no.
7、old-moose Behavior Population DynamicsMean Time to Extinction,Wolf PopulationWeak dependence,initial population sizeStandard result not observedStrong effect,initial number of packsBehavior Population DynamicsReproductive unit is packNumber packs,not population size criticalextinction processSocial
8、organization,with dominance-based breeding,amplifies effects of demographic stochasticity on extinctionBehavior Population DynamicsNo.old moose constant=305Wolves:MTE=155 yrsNo.old moose cycles,mean=305Wolves:MTE=105 yrsEnvironmental stochasticityStandard resulttntBehavior Population DynamicsInteractions among individual group membersInterference,independence,mutualismSurvival through non-breeding seasonComplexity of population dynamicsLikelihood of extinction谢谢你的阅读v知识就是财富v丰富你的人生谢谢
