Chapter 3 Chapter 3 Lesson 2Lesson 2

What Factors Affect Ecosystems?What Factors Affect Ecosystems?SPI’S: Science: 7.2.3, 7.5.2, 7.2.2, 7.2.3SPI’S: Science: 7.2.3, 7.5.2, 7.2.2, 7.2.3

Reading: 5.1.12, 5.1.3, 5.1.14, 5.1.16, 5.1.20Reading: 5.1.12, 5.1.3, 5.1.14, 5.1.16, 5.1.20Language: 1.1.5, 1.1.13, 1.5.2Language: 1.1.5, 1.1.13, 1.5.2

Main Idea Main Idea

The size of any population can vary over The size of any population can vary over time. It responds to change in climate time. It responds to change in climate and resources. and resources.

In This Lesson:In This Lesson:

We’ll learn how a decrease in food supply, We’ll learn how a decrease in food supply, changes in climate, and relocated species changes in climate, and relocated species can upset the balance of an ecosystem.can upset the balance of an ecosystem.

Vocabulary:Vocabulary:It’s journal time folks!!!It’s journal time folks!!!

ExtinctionExtinction PopulationPopulation PredatorPredator PreyPrey

Extinction: Extinction:

When all members of a species die outWhen all members of a species die out

Population:Population:

All the organisms of a given species that All the organisms of a given species that live together in the same arealive together in the same area

Predator:Predator:

Animal that hunts and eats other animalsAnimal that hunts and eats other animals

Prey:Prey:

Animal that is hunted and eaten by Animal that is hunted and eaten by predatorspredators

Hey, did you catch that?Hey, did you catch that?

Predator and Prey are…Predator and Prey are…

Antonyms!!!Antonyms!!!

(opposites)(opposites)

Let’s Talk Population…Let’s Talk Population…

Remember, a population is all the Remember, a population is all the organisms of a given species that live organisms of a given species that live together in the same area.together in the same area.

Let’s Talk Population…Let’s Talk Population… Population size responds to changes in Population size responds to changes in

climate and resources.climate and resources.

How do you think the birds on the previous How do you think the birds on the previous slide would respond to the 3 climate slide would respond to the 3 climate

examples listed below? examples listed below?

Let’s Talk Population…Let’s Talk Population…

In a healthy ecosystem, the population of In a healthy ecosystem, the population of predators and prey are balanced. predators and prey are balanced.

Changes in Population…Changes in Population…

Every ecosystem supports many populations. Every ecosystem supports many populations. That means many different species live in the That means many different species live in the same ecosystem. same ecosystem.

A population is all the organisms of a given A population is all the organisms of a given species that live together in the same area. species that live together in the same area.

Any change in one part of an ecosystem can Any change in one part of an ecosystem can upset the balance. upset the balance.

For Example:For Example:

Suppose a fungus kills many of the Suppose a fungus kills many of the plants that rabbits eat. Such an event plants that rabbits eat. Such an event could lower the rabbit population. This could lower the rabbit population. This would affect the hawks, owls, and other would affect the hawks, owls, and other animals that eat the rabbits.animals that eat the rabbits.

How would this affect the hawks, owls, How would this affect the hawks, owls, and other animals that eat the rabbits?and other animals that eat the rabbits?

Answer…Answer…

The hawks, owls, and other animals would The hawks, owls, and other animals would not have the rabbits to eat; therefore, they not have the rabbits to eat; therefore, they might go hungry. Or, they would have to might go hungry. Or, they would have to

find another food source which might find another food source which might cause another species to go hungry. cause another species to go hungry.

Can you see how a change in population Can you see how a change in population could upset the balance of an ecosystem? could upset the balance of an ecosystem?

Question…Question…

What would happen if a population of What would happen if a population of rabbits became too large?rabbits became too large?

Answer:Answer:

They would crowd out the other They would crowd out the other species in that area!!species in that area!!

Why would that be a bad thing?Why would that be a bad thing?

AnswerAnswer

Ecosystems have limited Ecosystems have limited resources, and can only support resources, and can only support a limited number of living things.a limited number of living things.

Hey…that makes sense!!!Hey…that makes sense!!!

Did you know…Did you know…

In an ecosystem, populations areIn an ecosystem, populations are

ALWAYS changing.ALWAYS changing. Old animals die, and new ones are born.Old animals die, and new ones are born. When a tree falls, plants that thrive in When a tree falls, plants that thrive in

sunlight can begin to grow.sunlight can begin to grow.

These are good changes!!!These are good changes!!!

Consider the relationship Consider the relationship between between

predators and their preypredators and their prey

Predators are animals that hunt and eat Predators are animals that hunt and eat other animals.other animals.

Prey are animals hunted and eaten by Prey are animals hunted and eaten by predators.predators.

(I’d rather be a predator!)(I’d rather be a predator!)

In a healthy ecosystem…In a healthy ecosystem…

The population densities of predators and The population densities of predators and prey are balanced. But remember, we prey are balanced. But remember, we

said certain factors can upset this said certain factors can upset this balance. balance.

For example: Predators and prey are two For example: Predators and prey are two factors that affect the balance of an factors that affect the balance of an

ecosystem.ecosystem.

Let’s Read About It:Let’s Read About It:

May I have a volunteer to begin May I have a volunteer to begin reading on P. 95, please? reading on P. 95, please?

How might a decrease in How might a decrease in predators affect prey?predators affect prey?

Answer:Answer:

The prey populationThe prey population

could grow.could grow.

Did you know…Did you know…

Once an ecosystem is changed it may take Once an ecosystem is changed it may take hundreds of years to recover!hundreds of years to recover!

In some cases, it is changed FOREVER!!In some cases, it is changed FOREVER!!

Let’s Review:Let’s Review:

What factors affect ecosystems?What factors affect ecosystems?

Answer:Answer:

PopulationPopulation

PredatorsPredators

PreyPrey

Review:Review:

What factors can cause the size of What factors can cause the size of a population of living things to a population of living things to

change?change?

Answer:Answer:

Climate changeClimate change Volcanic eruptionsVolcanic eruptions FiresFires DroughtsDroughts FloodsFloods Alien speciesAlien species Lack of resourcesLack of resources

Review:Review:((Cause and Effect)Cause and Effect)

Why do alien species often thrive Why do alien species often thrive in their new ecosystems?in their new ecosystems?

Answer:Answer:

Often the alien species have no Often the alien species have no natural predators in the new natural predators in the new

ecosystem.ecosystem.

Way To Go!!!Way To Go!!!

This is the end of Chapter 3 Lesson 2.This is the end of Chapter 3 Lesson 2.

Now it’s YOUR time to shine…Now it’s YOUR time to shine…

In your journal write everything you’ve In your journal write everything you’ve learned about the factors that affect learned about the factors that affect

ecosystems.ecosystems.

Make me proud champs!!!Make me proud champs!!!