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Examining Population Density and DispersionThe following image shows a world map of human population density. Discuss with your group, the patterns that you see. Consider- Where on the map do you see the greatest
population? The least population? - What “pattern of spacing” – or dispersion - do
you notice? - Why do you see this type of population
distribution and density?
Population Dynamics
Essential concept: Each population has a a) density, b) dispersion, and a c) survival/reproductive strategy.
Human Population Growth
What are the factors that affect human population growth?
World Population
Watch the history of world population growth in less than seven minutes
Dynamic Population Pyramids
The population pyramid is used by demographers to study the distribution of
people across age categories. Why do you think this is called a population pyramid?
Dynamic Population Pyramid
Understanding Exponentials
• Put your pens down for a minute & think about this:– An employer offers you two equal jobs for one hour
each day for fourteen days. – The first pays $10 an hour.– The second pays only 1 cent per hour, but the rate
doubles each hour.– Which job will you accept?
Understanding Exponentials
0102030405060708090
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Job 1 Job 2
Job 2 lags for a long time before
exponential growth kicks in!
Now, how much would your employer owe you if you stayed at this job for another 2 weeks?
What would happen if this type of growth took place
within a population?
1) Exponential growth model• Also called geometric growth or J-shaped growth.• First growth phase is slow and called the lag phase• Second growth phase is rapid and called the exponential
growth phase• Bacteria can grow at this rate, so why aren’t we up to our
ears in bacterial cells?
Population Growth Models
• Limits to exponential growth– As population density increases, competition follows
as nutrients and resources are used up– The limit to population size that a particular
environment can support is called carrying capacity (k)
– When you’re done writing, put your pens down…
Population Growth Models (cont.)