POPULATIONS(The Presentation)

Characteristics of Populations

How do you count members of a population? Geographic Distribution

Distribution is constant (plants – animals) Density # members of population / given area Used if distribution is constant or non-

moving Distribution is non-constant (animals)

Mark and Recapture

Geographic Distribution (continued) Population Growth

Factors affecting size (Predict how): # Births

INCREASE # Deaths

DECREASE # Enter Population Area (Immigration)

INCREASE # Leave Population Area (Emmigration)

DECREASE Formula for ZERO POPULATION GROWTH?

Discuss now with your table.

Types of Growth Rates

1) Exponential Growth J-shaped

Exponential Growth

If a population is experiencing exponential growth, then you know: 1) Unlimited resources are available. 2) Abundant space is available. 3) Protected from predators and

disease.

% Annual Natural Increase = Birth Rate - Death Rate / 10

Divide by 10 because Rates are usually given as x/1000 and if you divide this by 10, it gives the number as %

Can you make this equation more inclusive? = (Birth+Immigration)-(Death+Emmigration) /

10 Doubling by Law of 70:

Doubling Time (in years) = 70/Rate of Increase

If ONE bacterial cell was placed into a beaker that holds 512 bacterial cells total, and it splits in half every minute, at what point will the bacterial cells realize that their resources are no longer plentiful? Why?

At 8 minutes, bacteria are 1 minute away from completely using up their resources. (1 more doubling period…)

Logistic Growth Curve

Obviously, bacteria nor elephants cover the entire planet, so exponential growth doesn’t go on forever.

As resources become less available, the growth of a population slows or stops.

At which point are resources less plentiful or have a limiting affect upon population growth

Carrying Capacity (K) – the maximum number of organisms in a population that an environment can support.(Think of the “Oh Deer” activity we did in class.)

1) Which part of the curve does population experience unlimited resources?1) A

2) Which part of the curve does population first experience limiting resources:1) 1

1) If one were looking for the part of the graph showing the “Carrying Capacity” of the environment, where would one look on the graph?1) C or 2

2) If one were to look for the number of the Carrying Capacity, where would one look on the graph?1) D

Limits to Growth

Limiting Factors Anything that causes population growth

to decrease.

Limits to Growth

1) Density-Dependent Factors Limiting Factor that depends on

population size.

A) Competition B) Predation C) Parasitism and Disease

Limits to Growth

2) Density-Independent Factors Limiting Factor that does NOT depend

upon a population size.

A) Unusual weather B) Natural Disasters C) Seasonal Cycles D) Certain Human Activities

Distribute Limiting Factors Worksheet for Class Discussion.

Human Population

Human Population is doubling at a rate of 1.14% today in 2015.In what year will the population be at 14 Billion or 2x today’s population number?

61 years or the year 2076 - within your lifetime!

What will Human Population look like in 2076?

Or something more sustainable?

May have to think differently.