Limiting Factors

HMH Science Dimensions
Biology
Unit 4: Ecosystems: Stability and
Change
Lesson 1: Population Dynamics
Exploration 2: Factors that Limit Population Growth

2

Factors that Limit Population Growth

The carrying capacity of an environment is the maximum
population size of a species that a particular environment can normally and consistently support in terms of resources.

Unit 4 Lesson 1

How might this graph change if an ecosystem experienced drought conditions?

Poll

How might this graph change if an ecosystem experienced drought conditions?

• The carrying capacity would increase

• The carrying capacity would decrease

• The carrying capacity would be unchanged

3

Factors that Limit Population Growth

Populations reaching their carrying capacity may often
overshoot, meaning that more individuals are born than can
be supported. As a result there will be a die off before the
population stabilizes.

If the overshoot depleted too many resources, it could result in
population collapse instead of stabilization.

Unit 4 Lesson 1

die off

4

Factors that Limit Population Growth

Density–dependent limiting factors are factors that are affected by the number of individuals in an area.

Unit 4 Lesson 1

Density–independent limiting factors are factors that can impact a population regardless of its density.

Word Cloud

What limiting factors might be Density Dependent? (depend on how many individuals are in the population)

Word Cloud

What limiting factors might be Density Independent? (impact a population regardless of size)

4

Factors that Limit Population Growth

Density–dependent limiting factors:

Unit 4 Lesson 1

• Organisms compete among themselves for

needed resources.

• Predator and prey relationships
• Parasitism
• Disease spread

5

Factors that Limit Population Growth

Density–independent limiting
factors

Unit 4 Lesson 1

• Weather: Any weather-related event such as a drought, flood, frost,

or severe storm

• Natural Disasters: Volcanic eruptions, earthquakes, tsunamis, and fires

• Human Activities: forest clearing, draining of wetlands for land

development, and habitat fragmentation by roads and fences.

6

Factors that Limit Population Growth

ANALYZE
Study the graph showing the moose–wolf interactions on Isle Royale. Based on this graph:

What is the most likely explanation for the increase in the moose population between 1989 and 1995?

Unit 4 Lesson 1

Predator-Prey Interactions on Isle Royale

Open Ended

What is the most likely explanation for the increase in the moose population between 1989 and 1995?

7

Factors that Limit Population Growth

ANALYZE
In 2016, the wolf population on Isle Royale declined to
only two individuals.
How will the lack of wolves affect the moose population?

Will the moose population grow exponentially? Explain
your answers

Unit 4 Lesson 1

Predator-Prey Interactions on Isle Royale

Open Ended

ANALYZE
In 2016, the wolf population on Isle Royale declined to only two individuals. How will the lack of wolves affect the moose population?

Will the moose population grow exponentially? Explain
your answers

Poll

Did you like this type of lesson?

• yes

• no

• I'm indifferent

• Yes, but not the pace