Slide 1- Population GrowthWhen a population increases in size.

Slide 2Population Growth Question

Population A

2000 = 10 Cats

2010 = 12 Cats

2012 = 16 Cats

Population B

2000 = 20 Cats

2010 = 20 Cats

2012 = 20 Cats

Slide 3Another Population Growth Question

Population A

2000 = 10 Cats

2010 = 12 Cats

2012 = 14 Cats

Population B

2000 = 20 Cats

2010 = 21 Cats

2012 = 22 Cats

Slide 4 – Types of GraphsEcologists study graphs to see how population size changes.

Graphs are named by how they are shaped!

Linear Graph J-Shaped Graph S-Shaped Graph

Slide 5 - Linear GraphPopulations would grow at the same rate over

time. E.g. $3/Hour

Amount that you make every hour doesn’t change!

Slide 6 J-Shaped GraphLooks like a “J”

(aka Exponential Growth Graph)Growth exponentially increases!

Every hour you would make more and more money!

1st hour = $3

2nd hour = 32 = $9

3rd hour = 92 = $81

4th hour = 812 = $6561

Slide -7J-Shaped Graph Question

A

B

Slide 8Limiting Factors (aka Resources)

What an organisms needs to stay alive.If these are not available, individuals will die!

No Food

Too Hot or Too cold

No shelter

No Water.

Etc.

Slide 9How do populations grow in the wild?Stage 1 = Grow exponentially.Stage 2 = Too many individuals, resources in short supply.Stage 3 = Population stops growing (levels off) “K” = Carrying Capacity

Slide 10 - Carrying CapacityThe # of individuals the environment can support/carry.

More Resources = More BirthsLess Resources = More Deaths

Slide 11Demography

The study of human population size.

Slide12 - Human PopulationWe are still growing exponentially!

1800 = 1 Billion People2015 = 6 Billion People

2052 = 10 Billion People

Slide 13 - Human Limiting FactorsWe don’t have as many limiting factors as other species!We have not reached carrying capacity yet!

Because we have:

Medicine (get rid of diseases)

Clothing (to keep us warm)

Houses (protect us from weather)

Agriculture (massive amounts of food)

Slide 14Calculating A Country’s Growth RateGrowth Rate = (Births + Immigration) – (Deaths +

Emmigration)

Birth rate: # of Births

Death Rate: # of Deaths

Immigration: Individuals moving in a country.

Emigration: Individuals moving out of a country.

Slide 15 - Doubling TimeTime needed for a population to double in size.

Slide 16 - Age Structure% of people in each age group.

Countries with high % of young people, will grow faster

Countries with high % of old people, will grow slower.

Slide 17Some populations of species grow faster than

others!

Fast Life-HistoryGrow fast

Slow Life-HistoryGrow slow

Slide 18Rapid vs. Slow Life History

Condition Fast Life History

Slow Life History

Example Bacteria or Bugs Animals (e.g. Elephant)

Body Size Small Big

Birth to Adult Very Quick (hours to days) Very Slow (Years)

Good Conditions Population increases rapidly Population stays the same

Bad Conditions Population declines rapidly Population stays the same

Life Span Short (Hours to Days) Long (Years)

Slide 19 - Population Density# of individuals in an area.

Density-DependentFactors

Disease

Competition

Predators

Parasites

Food

Crowding/Stress

Density-IndependentFactors

Volcanic Eruptions

Temperature

Storms

Flood

Drought

Chemical Pesticides

Note: Most are abiotic!

Slide 20 - Patterns of DispersalDispersal = movement of species

Some like to move close together, far apart, or don’t care either way.

Slide 21 - Crowding and StressMost organisms get stressed when forced to live close.

Symptoms of Stress:

Aggression

Decrease in ability to care for children.

Decreased fertility (ability to have kids)

Lower Immune systems, get sick more often!