Download 3.3 Threats to Biodiversity (Pages100-109)

3.3 Threats to Biodiversity
(Pages100-109)
Learning Goals
• I can explain how biodiversity is
threatened by habitat loss, alien species,
overexploitation, disrupting connectivity
across ecosystems and extinction.
• I can explain how biodiversity is beneficial
to humans.
• I can suggest ways to preserve
biodiversity.
Key Concepts
• Threats to biodiversity
include habitat loss, the
introduction of alien
species, overexploitation,
and breaking the
connectivity among
ecosystems.
• Deforestation and
draining wetlands can
result in habitat loss.
• Zebra Mussels
Key Concepts
• Extinction is a
natural event that
has occurred
throughout Earth’s
history.
• Current extinction
rates may be
accelerated due to
human activities.
Habitat Loss
• Habitat loss: the destruction of habitats,
which usually results from human activities
• Examples
– Deforestation
– Draining Wetlands
Deforestation
• Deforestation: the
practice of clearing
forests for logging
or other human
uses, and never
replanting them
Draining Wetlands
• Wetlands: areas of
land that are covered
by water for part or all
of the year
• Important ecosystem
for many different
species
• Cover about 14
percent of Canada's
total land area
Importance of Wetlands
Alien Species
• Alien species: a species
that is accidentally or
deliberately introduced
into a new location
• Invasive species: a
species that can take
over the habitat of native
species
• Aliens Have Landed I
• Aliens Have Landed II
Overexploitation
• Overexploitation: the use or extraction of a resource until
it is depleted
• The reduced catch of Atlantic cod reflects a decrease in
population as a result of overexploitation
Disrupting Connectivity Across
Ecosystems
• Some species are responsible for
sustaining multiple ecosystems
Extinction
• Extinction: the death of all
the individuals of a
species
• Background extinction 
slow, steady, minor
changes
• Mass extinction 
sudden, rapid, major
changes
• Biodiversity crisis: the
current accelerated rate
of extinctions
Practice
• Page 109 # 1-8