Ecology - Populations NCERT

POPULATIONSPopulation AttributesPopulation ecologyLinks ecology to pop genetics and evolutionNatural selectionoperates at this levelBirth & death ratesper capita ratesoffspring/ individual/ yearchange in no./ no. of individualsSex ratioMales: FemalesAge groupsAge pyramidsAge distribution plotted w/ populationShapes reflect growth statusExpanding - TriangularStable - Bell shapeDeclining - Urn shapePopulation sizeExplainsStatus of organismsOutcome of competitionImpact of predatorRange<10 Siberian cranes @Bharatpur in a yearMilliions Chlamydomonas in a pondPopulation density N(Measure)Total numbergenerally most appropriateBiomass or Percent coverBanyan tree, 200 Parthenium histophorusRelative densitiesNo. of fish caught/ trap Indirect EstimationTiger census in NPPug marks & fecal pelletsPopulation GrowthFactorsFood availabilityPredation pressureAdverse effectsProcessesNatality BMortality DImmigration IEmigration EN(t+1) = N(t) +[(B+I)-(D+E)]Exponential Growth ModelUnlimited resourcesUnimpeded growthNo checksEnormous populationFollowed by crashJ shapeDensity independentdN/dt = (b-d)xN = rNN laglogcrashr valueflour beetle 0.12norway rat 0.0151981 Indians 0.02052021 Indians 0.0103N(t) = N(o) e^rtAphids, Algal bloomsLogistic Growth ModelLimited resourcesSurvival of fittestS shape - sigmoidDensity dependentNlag/ establishinglog/ exponentialdeaccelerationstabilizing/ asymptoteVerhulst-Pearl Logistic GrowthdN/dt = rN (K-N/K)K- carrying capacity(K-N/K) - environmental resistanceLife History VariationEvolutionto maximise rDarwinian fitnessmost efficient reproductive strategyin relation to constraintsimp area of researchOne-time breedersPacific Salmon, BambooMany-time breedersAves, MammalsMany small sized offspringOysters, Pelagic fishesFew large offspringBirds, Mammals
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