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Chapter 10: Biodiversity
Section 10.1:
Biodiversity at Risk
The last dinosaurs died about 65
million years ago.
The dinosaurs disappearance was
part of a mass extinction.
Akiapola’au
Mass
extinctions
are the
extinctions
of many
species during
a relatively
short period
of time.
Biodiversity refers to the
number and variety of
species on Earth.
• The number of species
known to science is about
1.6 million – most of
which are insects.
• The actual number of
species can range to about
13 million.
Blunt-Nosed
Leopard Lizard
Hawksbill Sea Turtle
The human population
of the world is increasing
at a rate of 220,000
people per day.
Because the human population is
growing so rapidly and changing the
environment so dramatically, we are
causing other species to become extinct
at an accelerated rate.
Why is the increase in
the human
population so
devastating to other
species?
WHIPSNAKE
• As humans take up more and more space
and deplete more resources, we destroy the
habitats of other species.
• Unregulated hunting and the introduction of
nonnative species also contribute to
extinctions.
It is estimated that
habitat loss causes almost
75% of the extinctions now
occurring.
Houston
Toad
Two United
States species
being destroyed
by habitat
destruction is the
Florida panther
and the
whooping crane.
However, most
extinctions are
occurring in tropical
rainforests when the
land is cleared for
farming or cattle
grazing.
Unregulated hunting in the U.S.
has lead to the decline of many
species including the passenger
pigeon and the bison.
BONE
CAVE
HARVESTMAN
Legal hunting is no longer a
problem in developed
countries.
Illegal hunting
called
poaching,
threatens
developing
countries’
organisms.
An exotic species is a species that
is not native to a particular region.
E
u
r
o
p
e
a
n
E
e
l
Exotic species can threaten
native species, which have no
defenses against them.
The Value of Biodiversity
Saving species preserves
ecosystems
It is important to
maintain healthy
ecosystems
because they
ensure a healthy
biosphere by
regulating the flow
of energy and the
cycling of nutrients.
Blackburn’s Sphinx
Moth
Practical Use of Species
The mass extinction of species
represents the loss of a potential
gold mine of valuable products.
Comal
Springs
Riffle
Beetle
About 40% of all
prescription drugs used in the
U.S. were originally made
from living things.
Digitoxin – Common
Foxglove
Cardiac Stimulant
Taxol – Pacific Yew
Anticancer Agent
Ethical and Aesthetic Reasons
Most people agree that
we should preserve
biodiversity for ethical
reasons.
People also value
biodiversity for aesthetic
reasons – time spent
with other living things
renews our sense of
connection with nature.
Appalachian
Monkeyface