Population Ecology and EcosystemsEcologyHuman Population ProblemsPopulationPopulation Age StructureDensity & DistributionDetermining Population SizeAssumptions in Capture-RecaptureChanges in Population SizeZero Population Growth- ZPGPer Capita RatesExponential GrowthrExponential Growth EquationBiotic PotentialLimiting FactorsCarrying Capacity (K)Logistic Growth EquationLogistic GrowthOvershooting CapacityResetting the Carrying CapacityDensity-Dependent ControlsDensity-Independent ControlsLife History PatternsLife TableSurvivorship CurvesHuman Population GrowthPowerPoint PresentationHow Humans have Side-Stepped density dependent controlsFuture GrowthResource ConsumptionEffects of Economic DevelopmentSlowing Growth in ChinaCommunity EcologyTypes of InteractionsCompetitionPredator-Prey InteractionsEcosystemsFood WebsFood Webs can be DisruptedSlide 41Other CyclesQuizPopulation Ecologyand EcosystemsPopulation Ecologyand EcosystemsConcepts and Applications: Chapters 40 & 43Basic Concepts: Chapters 27 & 30Concepts and Applications: Chapters 40 & 43Basic Concepts: Chapters 27 & 30http://darwin.bio.uci.edu/~sustain/bio65/lec16/b65lec16.htmEcologyEcology•Certain ecological principles govern the growth and sustainability of all populations •Human populations are no exception•Certain ecological principles govern the growth and sustainability of all populations •Human populations are no exceptionEcology: The study of how organisms interact with one another and with their environmentEcology: The study of how organisms interact with one another and with their environmentPopulationEcologyPopulationEcologyHuman Population ProblemsHuman Population Problems•Over 6 billion people alive•About 2 billion live in poverty•Most resources are consumed by the relatively few people in developed countries •Over 6 billion people alive•About 2 billion live in poverty•Most resources are consumed by the relatively few people in developed countries PopulationEcologyPopulationEcologyPopulationPopulation•A group of individuals of the same species occupying a given area•Can be described by demographics–Vital statistics such as size, density, distribution, and age structure •A group of individuals of the same species occupying a given area•Can be described by demographics–Vital statistics such as size, density, distribution, and age structure PopulationEcologyPopulationEcologyPopulation Age StructurePopulation Age Structure•Divide population into age categories•Population’s reproductive base includes members of the reproductive and pre-reproductive age categories•Divide population into age categories•Population’s reproductive base includes members of the reproductive and pre-reproductive age categoriesPopulationEcologyPopulationEcologyDensity & DistributionDensity & Distribution•Number of individuals in some specified area of habitat•Crude density information is more useful if combined with distribution data •Number of individuals in some specified area of habitat•Crude density information is more useful if combined with distribution data clumpednearly uniformrandomPopulationEcologyPopulationEcologyFig 40.2Determining Population SizeDetermining Population Size•Direct counts are most accurate but seldom feasible•Can sample an area, then extrapolate•Capture-recapture method is used for mobile species•Direct counts are most accurate but seldom feasible•Can sample an area, then extrapolate•Capture-recapture method is used for mobile speciesMark and RecaptureMark and Recapture# marked Captured = Number releasedTotal Captured Total PopPopulationEcologyPopulationEcologyAssumptions in Capture-RecaptureAssumptions in Capture-Recapture•Marking has no effect on mortality•Marking has no effect on likelihood to being captured•There is no immigration or emigration between sampling times•Marking has no effect on mortality•Marking has no effect on likelihood to being captured•There is no immigration or emigration between sampling timesPopulationEcologyPopulationEcologyChanges in Population SizeChanges in Population Size•Immigration adds individuals•Emigration subtracts individuals•Births add individuals•Deaths subtract individuals•Immigration adds individuals•Emigration subtracts individuals•Births add individuals•Deaths subtract individualsPopulationEcologyPopulationEcologyZero Population Growth- ZPGZero Population Growth- ZPG•Interval in which number of births is balanced by number of deaths•Assume no change as a result of migration•Population size remains stable•Interval in which number of births is balanced by number of deaths•Assume no change as a result of migration•Population size remains stablePopulationEcologyPopulationEcologyPer Capita Rates Per Capita Rates•Rates per individual•Total number of events in a time interval divided by the number of individuals•Per capita birth rate per month =Number of births per month Population size•Rates per individual•Total number of events in a time interval divided by the number of individuals•Per capita birth rate per month =Number of births per month Population sizePopulationEcologyPopulationEcologyExponential GrowthExponential Growth•Population size expands by ever increasing increments during successive intervals•The larger the population gets, the more individuals there are to reproduce•Population size expands by ever increasing increments during successive intervals•The larger the population gets, the more individuals there are to reproducePopulationEcologyPopulationEcologyFig 40.4rr•Net reproduction per individual per unit time•Variable combines per capita birth and death rates (assuming both constant)•Can be used to calculate rate of growth of a population•Net reproduction per individual per unit time•Variable combines per capita birth and death rates (assuming both constant)•Can be used to calculate rate of growth of a populationPopulationEcologyPopulationEcologyExponential Growth EquationExponential Growth EquationG = rN•G is population growth per unit time•r is net reproduction per individual per unit time•N is population sizeG = rN•G is population growth per unit time•r is net reproduction per individual per unit time•N is population sizePopulationEcologyPopulationEcologyBiotic PotentialBiotic Potential•Maximum rate of increase per individual under ideal conditions•Varies between species•In nature, biotic
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