KS4 Biology
Competition
1 of 24
© Boardworks Ltd 2004
Contents
Competition
What is competition?
Competition between animals
Competition in plants
Predator–prey relationships
Multiple-choice quiz
2 of 24
© Boardworks Ltd 2004
What is a population?
What is the difference between a population and
a community?
A population is the number of individuals of the same
species living in a certain habitat.
A community includes all the different species living
in a certain area.
The size of the population within a community can change
over time. What factors will affect population size?
competition
disease
predators
migration
3 of 24
© Boardworks Ltd 2004
What is competition?
Competition is one of the factors that affects population sizes.
What type of organisms compete for resources?
Competition occurs between different species…
4 of 24
© Boardworks Ltd 2004
What is competition?
Members of the same species also compete for resources.
Why do living things need to compete and what do they
compete for?
5 of 24
© Boardworks Ltd 2004
Contents
Competition
What is competition?
Competition between animals
Competition in plants
Predator–prey relationships
Multiple-choice quiz
6 of 24
© Boardworks Ltd 2004
What do animals compete for?
What four things do
animals in the same
species or animals of
different species have
to compete for?
food
water
space
mates
7 of 24
© Boardworks Ltd 2004
Niche competition
A niche is the position
that a living thing
occupies in a community.
It is a specialized type
lifestyle.
What happens if animals have overlapping niches?
Animals with overlapping niches compete.
The more the niches overlap, the greater the amount of
competition between the species.
What will happen if species compete for all aspects of
their niches?
8 of 24
© Boardworks Ltd 2004
Competition losers
If species compete for all
aspects of their niches,
eventually, one species
will better the other.
Competition results in
winners and losers.
What three things might happen to the less competitive
species?
 move to another area
 adopt new survival strategies
 become extinct in that area.
9 of 24
© Boardworks Ltd 2004
Contents
Competition
What is competition?
Competition between animals
Competition in plants
Predator–prey relationships
Multiple-choice quiz
10 of 24
© Boardworks Ltd 2004
What do plants compete for?
Plants also have to compete
for resources. What four
things do plants in the same
species or plants of different
species compete for?
light
minerals
water
space
11 of 24
© Boardworks Ltd 2004
Competition in the meadow – activity
12 of 24
© Boardworks Ltd 2004
Contents
Competition
What is competition?
Competition between animals
Competition in plants
Predator–prey relationships
Multiple-choice quiz
13 of 24
© Boardworks Ltd 2004
Animals that eat other animals
Populations of animals are often limited by the amount of food.
What are animals that eat other animals called?
predators
What are the animals that predators eat called?
prey
14 of 24
© Boardworks Ltd 2004
Predator and prey adaptations
How are predators and prey adapted to survive?
Predators are adapted to catching and consuming their prey.
predators
Prey have adaptations to detect and flee from predators.
prey
15 of 24
© Boardworks Ltd 2004
Prey adaptations – the snowshoe hare
The snowshoe hare lives in northern parts of North America.
How is it adapted to the cold and to avoid being eaten by
predators, such as lynxes?
Coat changes colour
with the seasons from
greyish-brown in summer
to white in midwinter.
Large ears help to
detect predators.
Strong teeth are able to
chew bark and twigs.
Large back feet spread
out to act as snow shoes.
Fur on the soles also
protects from the cold.
16 of 24
© Boardworks Ltd 2004
Predator adaptations – the lynx
Lynxes are adapted to life in a cold climate. How are these
predators adapted for catching the snowshoe hares that are
their main prey?
Excellent eyesight and
hearing for detecting prey.
Very sharp teeth – prey
watch out!
Thick furry coat protects
from the cold.
Very strong hind leg
muscles are capable of a
pounce 6.5 metres long!
Extra large paws act as
snow shoes on soft,
deep snow.
17 of 24
© Boardworks Ltd 2004
Predator–prey graph
estimated population size
(thousands)
This population data comes from fur trapping records.
How are the populations linked?
snowshoe
150
hare
lynx
100
50
0
1800
1820
1840
1860
1880
1900
year
18 of 24
© Boardworks Ltd 2004
Predator–prey graph
estimated population size
(thousands)
How does the lynx population depend on the number of
snowshoe hares?
snowshoe
150
Take a closer
hare
look at this part
lynx
of the graph.
100
50
0
1800
1820
1840
1860
1880
1900
time (year)
19 of 24
© Boardworks Ltd 2004
Predator–prey graph section
Why does the peak for the lynx population always come after
the peak for the number of snowshoe hares?
snowshoe
hare
lynx
estimated population size
(thousands)
150
100
For the populations
to survive, there
will always be more
hares than lynxes.
50
0
1850
1855
1860
1865
time (year)
20 of 24
© Boardworks Ltd 2004
Predator–prey cycle
Predator and prey population sizes follow a cycle.
What happens if the prey population increases?
normal prey population
prey population
prey population
increases
increases
predator
population
decreases
as less food
21 of 24
prey population decreases
because of more predators
predator
population
increases
as more food
© Boardworks Ltd 2004
Predator–prey cycle
Predator and prey population sizes follow a cycle.
What happens if the prey population decreases?
normal prey population
prey population
prey population
decreases
increases
predator
population
decreases
as less food
22 of 24
prey population increases
because of less predators
predator
population
increases
as more food
© Boardworks Ltd 2004
Contents
Competition
What is competition?
Competition between animals
Competition in plants
Predator–prey relationships
Multiple-choice quiz
23 of 24
© Boardworks Ltd 2004
Multiple-choice quiz
24 of 24
© Boardworks Ltd 2004