population a closer look. population equation r = (b-d)+(i-e) birth rate death rate immigration...
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Population
A Closer LookA Closer Look
Population Equation
r = (b-d)+(I-e) Birth rate Death rate Immigration Emigration The growth rate (r) is
expressed in a percentage
Reproductive strategies
r-selected k-selected
Maturation Short Long
Body Size Small Large
Lifespan Short Long
# offspring/event Many Few
Age of reproduction Early Late
# birth events/life 1 >1
Parental care none Yes
Survivorship Curves
Human Population
A Look at the
Human Race
Rich Nations/Poor Nations 3 main economic categories in 2
classesDeveloped countries - high income,
highly developed, industrialized countries(US, Canada, Japan, E. Asia, Western Europe)
•Developing countries
•Middle income, moderately developed- Latin America, West Africa, E. Asia, E, Europe, Former USSR, Brazil
•Low income countries - E. Central Africa, India, Central Asia, Ethiopia
21%of the population is in developed countries. They control 80% of the world’s wealth
General Pyramid structures
POPULATION STRUCTUREThe population pyramid displays the age
and sex structure of a country or given area
Population inFive Year
Age bands
Usually, but not always,In % to make for easier
comparisonsbetween countries
OLD DEPENDANTS
ECONOMICALLYACTIVE
YOUNG DEPENDANTS
FEMALESTo the rightMALES
To the left
What Population Pyramids Show Us
KEYslope of pyramid indicate the death rate
width of the base is related to birth rate/fertility rate
proportions of men and women can suggest male or female migrations
height of graph can indicate life expectancy (ignore the very thin end of the wedge as occurs on graph B as these people are a definite minority)
"kinks" indicate dramatic reductions in birth rate or increases in death rate in the past
area of graph indicates total population - compare areas of differentpopulation age groups or different sex on one graph
The overall shape of the population pyramid can indicate whether it is an Economically More Developed Country or Economically Less Developed Country
Economically More Developed Country
Economically LessDeveloped Country
Population Pyramids related to the Demographic Transition Model
Stage 1 Stage 2 Stage 3 Stage 4
Both birth rates andDeath rates areHigh, so populationgrowth rates are slow but populationIs usually restoredDue to high birth Rate. Short lifeExpectancy
EXAMPLESNew Guinea
Population startsto grow at anexponential rate due to fall in Crude Death Rate. More living In middle age.Life expectancy risesInfant mortality rate falls.
EXAMPLESRepublic of Congo
Population continuesto grow but at slowerrate. Low C Death Rate.Dramatically decliningCrude Birth Rate.
EXAMPLESAlgeria, TunisiaMorocco
IMPLICATIONS IMPLICATIONS IMPLICATIONS IMPLICATIONS
Low Crude Birth Rate and Crude Death RateHigher dependancy ratioand longer life expectancyCrude Death Rate does Rise slightly because ofThe ageing population
EXAMPLES
Japan, USA
There is some merit in including or considering a Stage 5 today with a declining population