ES 4.2 LESSON

© 2017 Cengage Learning. All Rights Reserved.

Environmental Science, 1e
SUSTAINING YOUR WORLD
G. TYLER MILLER | SCOTT E. SPOOLMAN

4

Biodiversity and Evolution

© 2017 Cengage Learning. All Rights Reserved.

• Niche

– The role the species plays in an ecosystem and everything that

affects its survival and reproduction

• Habitat

– The geographic location of the species

• Species

– May be generalists with broad niches, or specialists with narrow

niches

4.2 What Roles Do Species Play in Ecosystems?

Multiple Choice

The role a species plays in an ecosystem is its...

• habitat

• niche

• trophic level

• abiotic factor

Multiple Choice

The geographic area a species lives in

• habitat

• niche

• trophic level

• abiotic factor

© 2017 Cengage Learning. All Rights Reserved.

• Generalist species (broad niches)

– Eat wide variety of foods

– Can live in a wide range of environments

– More resource competition but less prone to extinction

• Specialist species (narrow niches)

– Have specialized diets

– Live in only a few types of habitats

– Less competition but more prone to extinction

Generalist and Specialist Species

Categorize

Options (8)

eat a variety of foods

live in wide range of habitats

more competition

less chance of extinction

only eat specific foods

live in a few habitats

less competition

prone to extinction

Organize these options into the right categories

Generalist Species

Specialist Species

© 2017 Cengage Learning. All Rights Reserved.

A Specialist and a Generalist

Labelling

Label the correct niches.

Drag labels to their correct position on the image

generalist niche

specialist niche

© 2017 Cengage Learning. All Rights Reserved.

Specialization Reduces Competition

Multiple Choice

What effect does specialization have on competition?

• specialization reduces competition

• specialization has no effect on competition

• specialization increases competition

Multiple Choice

How do many different birds feed in the same coastal area without having to compete?

• They each eat at different times of the day

• They each eat at slightly different depths

• They take turns and help each other out

• They each feed on a different species of prey

© 2017 Cengage Learning. All Rights Reserved.

• Native species

– Naturally originated in a specific ecosystem, suited to conditions

there

• Nonnative species

– Immigrate or are introduced (deliberately or accidentally) into an

ecosystem

– Can become invasive

• Outcompete/displace native species

• Spread rapidly if they find a favorable niche

• Often lack predators, disease faced in native habitat

Native and Nonnative Species

Multiple Select

How might a non-native species enter an area?

Choose all correct answers

• immigrate

• emigrate

• introduced accidentally

• introduced intentially

Multiple Choice

What do we call nonnative species that outcompete native species and lack predators?

• invasive

• erosive

• extinct

• endangered

© 2017 Cengage Learning. All Rights Reserved.

• Keystone species affect the type and abundance of other

species in an ecosystem.

– Ecosystem would be dramatically different if keystone species

disappeared

• Regulation of populations of other species (mountain lions, wolves, sea

otters)

• May cause population crashes and extinction of dependent species if drawn

to extinction itself

Keystone Species Play Critical Roles in Their Ecosystems

Multiple Choice

What do we call a species that has a large impact on the abundance of several other species in an ecosystem?

• invasive species

• keystone species

• specialized species

• generalized species

• indicator species

Multiple Choice

Which animal is most likely a keystone species?

(Hint: It affects the most species)

• mouse

• frog

• deer

• grasshopper

© 2017 Cengage Learning. All Rights Reserved.

• The American alligator is a keystone species of subtropical

wetland ecosystems in the Southeastern United States.

– Gator holes provide fresh water, habitat for aquatic life,

nesting/feeding sites for other species

– Digging activity maintains balance of vegetation

– Helps control predatory fish populations

– Almost hunted to extinction, endangered species until 1987 (now

threatened by invasive pythons)

American Alligator as a Keystone Species

Multiple Choice

Do alligators help control vegetation growth?

• Yes, they are herbivores

• Yes, with their digging activity

• No, they are carnivores

• No, their waste fertilizes vegetation

© 2017 Cengage Learning. All Rights Reserved.

• Sharks are keystone species that keep their ecosystems

functioning and help maintain healthy distributions of other
marine species.

– Over a million are killed annually in response to exaggerated media

reports on shark attacks.

– Populations of many shark species are sharply declining, mainly

due to finning.

• As many as 73 million killed annually

• 25% of world’s open-ocean shark species threatened

• Vulnerable due to slow growth, low reproductive rates

Sharks as Keystone Species

Multiple Choice

Which statement about humans and sharks is true?

• humans kill more sharks every year

• sharks kill more humans every year

© 2017 Cengage Learning. All Rights Reserved.

• An indicator species is sensitive to changes in an ecosystem.

– Presence or absence indicates the quality or characteristics of

certain environmental conditions

– Some amphibian species are good indicator species (Case Study)

• Natural environmental factors: virus, fungal disease, parasites

• Human-related factors: habitat loss, pollution, climate change

Indicator Species Serve as a Biological Smoke Alarm

Multiple Choice

Which of these is typically an indicator species?

• shark

• alligator

• amphibian

• insect

Multiple Select

Indicator species can indicate the quality of which NATURAL ENVIRONMENTAL factors in an ecosystem?

• fungal disease

• parasites

• pollution

• climate change

Multiple Select

Indicator species can indicate the quality of which HUMAN-RELATED factors in an ecosystem?

• fungal disease

• parasites

• pollution

• climate change