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A population is the number of individuals of the same species living in a certain habitat.

What is the difference between a population and a community?

What is a population?

A community includes all the different species living in a certain area.

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What is a population?

The size of the population within a community can change over time. What factors will affect population size?

competition predators

disease migration

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Competition occurs between different species…

Competition is one of the factors that affects population sizes. What type of organisms compete for resources?

What is competition?

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Why do living things need to compete, and for what do they compete?

Members of the same species also compete for resources.

Why do animals compete?

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What four things do animals have to compete for?

What do organisms compete for?

food

mates

water

space

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What four things do plants have to compete for?

What do organisms compete for?

light

minerals

water

space

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What happens if animals within a community have overlapping niches?

A niche is the position that an organism occupies in a community.

Niche competition

Animals with overlapping niches compete. The greater the overlap between niches, the greater the amount of competition between the species.

A niche organism has a specialized type of lifestyle.

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What three things might happen to the less competitive species?

If species compete for all aspects of their niches, one species will better the other.

become extinct in that area.

move to another area

adopt new survival strategies

Competition losers

Competition results in winners and losers.

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Competition in the meadow

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A predator is an animal that hunts and kills other animals for food.

A prey animal is one that is attacked and eaten by a predator.

Predators can be either:

Animals that eat other animals

carnivorous (eat meat only) e.g. wolves

omnivorous (eat meat and vegetation) e.g. humans.

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Predators are adapted to hunting, catching and eating prey.

Prey are adapted to detecting and fleeing predators.

Predator and prey adaptations

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The snowshoe hare lives in northern parts of North America. How is it adapted to avoid predators such as lynxes?

large furry feet act as snow shoes and protect the soles from cold

large ears help in detecting predators

greyish-brown fur turns white in winter for camouflage

strong teeth for chewing bark and twigs

Prey adaptations

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How are lynxes adapted for catching snowshoe hares?

very strong hind leg muscles capable of pouncing 6.5 metres! extra large paws

act as snow shoes

excellent eyesight and hearing, and very sharp teeth!

warm thick furry coat protects from the cold

Predator adaptations

sharp claws for puncturing flesh

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This population data comes from fur trapping records. How are the populations linked?

Predator-prey populations

0

50

esti

mat

ed p

op

ula

tio

n s

ize

(th

ou

san

ds)

1800 1820 1840 1860 1880 1900

100

150

year

lynx

snowshoe hare

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How does the lynx population depend on the number of snowshoe hares?

Predator-prey populations

0

50

esti

mat

ed p

op

ula

tio

n s

ize

(th

ou

san

ds)

1800 1820 1840 1860 1880 1900

100

150

year

lynx

snowshoe hare

Take a closer look at this part

of the graph.

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1850

Why does the peak for the lynx population always come after the peak for the number of snowshoe hares?

Predator-prey populations

0

50

esti

mat

ed p

op

ula

tio

n s

ize

(th

ou

san

ds)

1845 1855 1860 1865

100

150

year

lynx

snowshoe hare

For the populations to survive, there must always

be more hares than lynxes

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Predator and prey population sizes follow a cycle.What happens if the prey population increases?

Predator-prey cycle

normal prey population

prey population increases

prey population decreasesbecause of more predators

prey populationincreases

predator population increases because

of more food

predator population decreases because

of less food

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Predator and prey population sizes follow a cycle.What happens if the prey population decreases?

Predator-prey cycle

normal prey population

prey population decreases

prey population increasesbecause of fewer predators

prey populationdecreases

predator population increases because

of more food

predator population decreases because

of less food

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Glossary

competition – The struggle for resources between individuals of the same or different species.

community – All the different types of species within a specific area.

niche – The position that an organism occupies in a community.

population – The number of one particular species within a specific area.

predator – An animal that hunts and kills other animals for food.

prey – An animal that is killed and eaten by another animal.

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Anagrams

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Multiple-choice quiz