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pre-AP Bio 5.2

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Limits to Growth

Text of pre-AP Bio 5.2

  • 1. Limits to Growth

2. Learning Objectives Identify factors that determine carrying capacity. Identify the limiting factors that depend on populationdensity. Identify the limiting factors that do not depend onpopulation density. 3. Limiting FactorsLimiting factors determine the carrying capacity of an environmentfor a species.Density dependent Density independent 4. Density-Dependent FactorsDensity-dependent limiting factors operate strongly whenpopulation density reaches a certain level. 5. Competition More individuals use upresources sooner. Individuals may competefor food, water, space,sunlight, shelter, mates,territories. 6. PredatorPrey Relationships 7. Herbivore EffectsPopulations of herbivores and plants cycle up and down likepopulations of predators and prey. 8. Parasitism and Disease Parasites and diseases can spread quickly through densehost populations. Stress from overcrowding can lead to lower birth rates,higher death rates, and higher emigration rates. 9. Density-Independent FactorsDensity-independent limiting factors affect all populationsregardless of population size and density. 10. Density-Independent Factors Examples: hurricanes,droughts, floods, wildfires Density-independent factorsmay actually vary withpopulation density.Canyon Lake, TX 11. Controlling Invasive SpeciesDensity-independent measures? Herbicides, mechanical removalDensity-dependent measures? PredationExpensive,temporaryAnother invasivespecies?Salvinia 12. Overview: Limits to GrowthDensity dependentDensity independentFlood waters cover afield of wildflowers.Non-native snakesreleased into a wetlandprey on native rodents.Flu virus spreads quicklyin schools.Wildfires spread througha grassland.