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