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APES Ch. 6, part 2
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APES Ch. 6, part 2


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  • 1. UnderstandingUnderstanding Population GrowthPopulation Growth
  • 2. Age Structure Pre-reproductive Reproductive Post-reproductive
  • 3. This group has a large economic impact
  • 4. Mostly older people Declining quickly
  • 5. Is a declining population a problem? YES!
  • 6. Problems Decreased economic growth Labor shortage – so more immigrant labor Less taxes – fewer workers  health care costs  pension costs – burden to taxpayers retirement age
  • 7. Other countries with these problems Germany Russia Poland Italy Spain Greece
  • 8. AIDS 25 million people dead as of 2008 Kills adults 8 African countries have 16-39% of their adults infected with HIV Loss of workers Loss of people to raise kids and care for elderly
  • 9. How Does IndustrializationHow Does Industrialization Affect Population Size?Affect Population Size? TheThe DemographicDemographic TransitionTransition
  • 10. Overall Shows what happens to countries as they move from developing to developed nations Economic development and family planning are key factors Overall: first the death rate goes down, then the birth rate
  • 11. FactorsFactors InfantInfant MortalityMortality RateRate numbernumber of babiesof babies per 1000per 1000 that don’tthat don’t make it tomake it to their 1st yrtheir 1st yr reflectreflect
  • 12. AverageAverage CrudeCrude Birth &Birth & CrudeCrude DeathDeath RatesRates
  • 13. Stage 1: Pre-Stage 1: Pre- IndustrialIndustrial High birth rateHigh birth rate (high IMR)(high IMR) High death rateHigh death rate Low pop growthLow pop growth
  • 14. Stage 2: TransitionalStage 2: Transitional IndustrializatioIndustrializatio nn  foodfood availabilityavailability  Health careHealth care Birth rate staysBirth rate stays highhigh Death rateDeath rate begins to fallbegins to fall Pop growsPop grows Some countries get stuck here
  • 15. Stage 3:Stage 3: IndustrialIndustrial Birth rate falls toBirth rate falls to near death ratenear death rate better jobs andbetter jobs and education foreducation for womenwomen Decline in IMRDecline in IMR Pop growth ratePop growth rate continues, but iscontinues, but is
  • 16. Stage 4:Stage 4: Post-IndustrialPost-Industrial Birth rate fallsBirth rate falls moremore birth rate =birth rate = death ratedeath rate ZPGZPG
  • 17. Stage 4: Post-IndustrialStage 4: Post-Industrial Then, birth rateThen, birth rate declines more; lessdeclines more; less than death rate,than death rate, negative pop growthnegative pop growth UnUnsustainability tosustainability to sustainabilitysustainability Very fewVery few countriescountries have made it herehave made it here
  • 18. Calculations
  • 19. Population DensityPopulation Density # of indiv. of a species# of indiv. of a species unit of areaunit of area  A better way to describeA better way to describe thethe size of a populationsize of a population
  • 20. Dependent on:Dependent on: Birth rate (Birth rate (bb )) Death rate (Death rate (dd )) Immigration (Immigration (ii )) Emigration (Emigration (ee )) What Causes PopulationsWhat Causes Populations to Change in Size?to Change in Size?
  • 21. Rate of change (Rate of change ( rr ) =) = birth rate (birth rate (bb)-death rate ()-death rate (dd ) x) x 100100 r = 40 - 20r = 40 - 20 1000 10001000 1000 rr =0.04 - 0.02 x 100 = 2% per=0.04 - 0.02 x 100 = 2% per What Causes PopulationsWhat Causes Populations to Change in Size?to Change in Size?
  • 22. Rule of 70 A way to estimate the number of years it takes for a certain variable to double. The rule of 70 states that in order to estimate the number of years for a variable to double, take the number 70 and divide it by the growth rate of the variable.
  • 23. Time to take for a populationTime to take for a population with a stable growth rate towith a stable growth rate to double in sizedouble in size Doubling Time (Doubling Time ( ttdd ) =) = ttdd = 70= 70 rr Doubling TimeDoubling Time
  • 24. Doubling TimeDoubling Time
  • 25. Growth Rate of a Pop.Growth Rate of a Pop. rr = (= (b - db - d ) + () + (i - ei - e )) b = .01b = .01 d = .005d = .005 i = .001i = .001 e = .01e = .01 Calculate growth rateCalculate growth rate Calculate doubling timeCalculate doubling time
  • 26. Proportion of a population toProportion of a population to survive tosurvive to breeding agebreeding age TypeType II==  survivalsurvival decreasesdecreases with agewith age TypeType IIII ==  survivalsurvival doesn’t changedoesn’t change withwith ageage TypeType IIIIII == SurvivorshipSurvivorship
  • 27. Questions to consider 1. What kind of survivorship do humans have? Explain why you think this. 2. How does parental care affect the survivorship curves? 3. What kind of curve for a redwood tree? A sea turtle? A squirrel? Why?