1. Population Models
Chapter 16.1 section 1
Population
•All the individuals of a species in one place at
one time.

2. Answer the following questions using
the pictures on the next slide.
1. What populations besides alligators could you
find in this ecosystem?
2. What do these these different populations
taken together represent?
3. What does the ecosystem include in additions
to the living things you see here?

3. Answers are on next slide.

4. Check Your Answers
1. What populations besides alligators could you find
in this ecosystem? Grasses, fish, trees, owls,
mangroves, bats, and other organisms
2. What do these these different populations taken
together represent? A community
3. What does the ecosystem include in additions to
the living things you see here? Abiotic factors, such
as water, soil, and sunlight.

5. • Watch the first video titled, “World Populations”.
(view it in full-screen-mode)
• As you can see, human population will continue to grow
exponentially if there are unlimited resources available.
Look, Black
Death that killed
50% of Europe's
population didn’t
have a huge
effect!

6. Using what you just learned, draw your own
Exponential Grow Curve
Number of
individuals
in a
population
Time
Answer is available on next page, don’t erase your original answer.
Make correction with another color pen.

7. Check your Exponential Growth Curve.
It should look like this
Answer is available on next page, don’t erase your original answer.
Make correction with another color pen.
Number of individuals
in a population
Write these down!
•J-shape Time
•Population doubling every year
•Population will continue to grow exponentially if there are
unlimited resources available.

8. Exponential growth is
impossible to maintain
in an ecosystem!!
• Something would always limit the population’s
growth.
• Watch the second video titled, “Populations”

9. • As you saw in the video, an environment determines
how many individuals of the species can be
supported.
• This is called Carrying Capacity.
• Logistic growth curve would be used to show this.
• Picture a population of grasshoppers that feed on
meadow grasses. If a a fire burns part of the
meadow, the insects’ food resources diminish, and
grasshopper population would no longer grow.

10. Using what you just learned, draw a your own
Logistic Growth Curve
and label where carrying capacity is reached.
Number of
individuals
in a
population
Time
Answer is available on next page, don’t erase your original answer.
Make correction with another color pen.

11. Your Logistic Growth Curve
should look like this
Make correction with another color pen.
Carrying
Capacity
Number of
individuals
in a
population
Write these down! Time
S-shaped
Carrying capacity is when Birth rate = Death rate

12. What could limit the population growth?
1. Density dependent limiting factor
– Affected by the number of individuals.
Larger the number of population, more of the
the resources are limited.
– Examples:
• competition,
• predation (predator and prey relationship)
• parasitism/disease
Watch the third video titled, “Golden Eagle vs. Jackrabbit”

13. Predation is shown in a
Boom and Bust Model
• The population of a
predator can be limited
by the available prey.
• The population of prey
can be limited by being
caught for food.
• Over time, the two
populations rise and
fall in a pattern

14. Draw your own Boom and Bust Curve
Number of
individuals
in a
population
Time
Use two different colors. One for predator population and
one for the prey population.

15. What could limit the population growth?
2. Density independent liming factor
–Aspect of the environment that limit a
population's growth regardless of the density of
the population.
–Examples:
• Unusual weather,
• Natural disaster,
• Human activities

16. Label the following scenarios as
Population Density dependent or
Population Density Independent limiting factor?
1. Imagine that scientists introduced a disease into the rabbit
populations of Australia, and the rabbit population crashed. Which
type of limiting factor caused the crash?
2. A species of beetle is in a period of exponential growth, but a
competing species has started sharing the same space. Which type
of limiting factor did this competition cause?
3. A population of prairie dogs is experiencing high immigration and
birthrate, but there are plentiful of resources available to support the
population growth. A tornado hits the area and causes a huge
destruction to a population of prairie grasses, their main food source.
Which type of limiting factor would decrease the population?
Answers are on next slide.

17. Check your answers!
Population density dependent or independent?
1. Population density dependent.
Disease can spread more easily in a dense population
2. Population density dependent.
Increase in population of community causing them to
compete for space.
3. Population density independent
Tornado hitting the area was not caused the increase
in
population.
Bonus: Draw a graph to show this type of sudden decrease in
population growth. (you can check your answer with Mrs. Majoros.