1. UnderstandingUnderstanding
Population GrowthPopulation Growth

2. Age Structure
Pre-reproductive Reproductive
Post-reproductive

4. This group has a
large economic
impact

5. Mostly older
people
Declining
quickly

6. Is a declining population a problem?
YES!

7. Problems
Decreased economic growth
Labor shortage – so more immigrant
labor
Less taxes – fewer workers
 health care costs
 pension costs – burden to taxpayers
retirement age

8. Other countries with these problems
Germany
Russia
Poland
Italy
Spain
Greece

9. 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

10. How Does IndustrializationHow Does Industrialization
Affect Population Size?Affect Population Size?
TheThe
DemographicDemographic
TransitionTransition

11. 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

13. 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

14. AverageAverage
CrudeCrude
Birth &Birth &
CrudeCrude
DeathDeath
RatesRates

16. 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

17. 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

18. 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

19. Stage 4:Stage 4:
Post-IndustrialPost-Industrial
Birth rate fallsBirth rate falls
moremore
birth rate =birth rate =
death ratedeath rate
ZPGZPG

21. 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

22. Calculations

23. 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

24. 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?

26. 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?

27. 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.

28. 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

29. Doubling TimeDoubling Time

30. 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

31. 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

34. 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?