Biodiversity
What is Biodiversity?
The number and variety
of different species in a
given area.
Number of Species on Earth
 1.9

million known species
Estimated 9 million species exist.

May exist in remote wildernesses, deep in the
oceans and even in cities. They have not been
collected and classified.
Levels of Diversity
 Species
diversity- refers to the number of
different species in an area.
 Ecosystem diversity- refers to the variety of
habitats, communities, and ecological
processes within and between ecosystems.
 Genetic diversity- refers to all the different
genes contained within all members of a
population.
Benefits of Diversity
 More
species that exist, the better the
balance in an ecosystem.
 Medical- 74% of the top 150 prescription
drugs used in the US are derived from plants.
 Food- most crops originated from a few areas
of high biodiversity.
 Aesthetic or personal enjoyment
 Clean air, clean water and fiber for clothing.
Biodiversity at Risk
 Humans
are the primary cause of species
extinctions!!
Lemurs
 90%
of Lemur species face extinction.
 Only found in Madagascar.
 Reason:

Illegal logging of tropical rainforests. Only 18% of
rain forest remain.
Core Case Study:
The Passenger Pigeon - Gone
Forever
 Once
the most
numerous bird on earth.
 In 1858, Passenger
Pigeon hunting became
a big business.
 By 1900 they became
extinct from overharvest and habitat
loss.
Figure 11-1
SPECIES EXTINCTION
 Species



can become extinct:
Locally: A species is no longer found in an area
it once inhabited but is still found elsewhere in
the world.
Ecologically: Occurs when so few members of a
species are left they no longer play its ecological
role.
Globally (biologically): Species is no longer
found on the earth.
Global Extinction
 Some
animals have become prematurely
extinct because of human activities.
Figure 11-2
Passenger pigeon
Great auk
Dodo
Dusky seaside
sparrow
Aepyornis
(Madagascar)
Fig. 11-2, p. 223
Endangered and Threatened
Species: Ecological Smoke Alarms
 Endangered
species: so few individual
survivors that it could soon become extinct.
 Threatened species: still abundant in its
natural range but is likely to become
endangered in the near future.
Figure 11-3
Giant panda Black-footed Whooping
crane
ferret
Mountain gorilla Florida
panther
California
condor
Northern
spotted owl
Hawksbill
sea turtle
Blue whale
Black
rhinoceros
Fig. 11-3, p. 224
HABITAT LOSS, DEGRADATION,
AND FRAGMENTATION
 Conservation
biologists summarize the most
important causes of premature extinction as
“HIPPO”:





Habitat destruction, degradation, and
fragmentation
Invasive species
Population growth
Pollution
Overharvest
SPECIES
EXTINCTION
 Some
species
have
characteristics
that make them
vulnerable to
ecological and
biological
extinction.
Figure 11-4
Characteristic
Low reproductive
rate
(K-strategist)
Specialized niche
Narrow distribution
Examples
Blue whale, giant panda,
rhinoceros
Blue whale, giant panda,
Everglades kite
Many island species,
elephant seal, desert pupfish
Feeds at high trophic Bengal tiger, bald eagle,
grizzly bear
level
Fixed migratory
patterns
Blue whale, whooping crane,
sea turtles
Rare
Many island species,
African violet, some orchids
Commercially
valuable
Snow leopard, tiger,
elephant, rhinoceros,
rare plants and birds
Large territories
California condor, grizzly
bear, Florida panther
Fig. 11-4, p. 225
SPECIES EXTINCTION
 Scientists
use measurements and models to
estimate extinction rates.



The International Union for the Conservation of
Nature and Natural Resources (IUCN) publishes
an annual Red List, listing the world’s threatened
species.
The 2004 Red List contained 15,589 species at
risk for extinction.
2014 Red list now contains 22,000 species at risk
for extinction.
Figure 11-5
SPECIES EXTINCTION
 Percentage
of various species types
threatened with premature extinction from
human activities.
Figure 11-5
34% (51% of freshwater species)
Fish
25%
Mammals
20%
Reptiles
Plants
Birds
14%
12%
Fig. 11-5, p. 225
Coral Reefs
 60%
of Earth’s coral reefs are threatened by
human activities: overfishing, and pollution.
HABITAT LOSS, DEGRADATION,
AND FRAGMENTATION
 Reduction
in
ranges of four
wildlife species,
mostly due to
habitat loss
and
overharvest.
Figure 11-8
Indian Tiger
Range 100 years ago
Range today
(about 2,300 left)
Fig. 11-8a, p. 230
Black Rhino
Range in 1700
Range today
(about 3,600 left)
Fig. 11-8b, p. 230
African Elephant
Probable range 1600
Range today
Fig. 11-8c, p. 230
Asian or Indian Elephant
Former range
Range today
(34,000–54,000 left)
Fig. 11-8d, p. 230
Case Study:
A Disturbing Message from the Birds
 Human
activities are causing serious declines
in the populations of many bird species.
Figure 11-9
Pollution
 Each




Example of biomagnification
of DDT in an aquatic food
chain.
year pesticides:
Kill about 1/5th of the
U.S. honeybee
colonies.
67 million birds.
6 -14 million fish.
Threaten 1/5th of the
U.S.’s endangered
and threatened
species.
Figure 11-15
DDT in fish-eating
birds (ospreys)
25 ppm
DDT in large fish
(needle fish)
2 ppm
DDT in small
fish (minnows)
0.5 ppm
DDT in
zooplankton
0.04 ppm
DDT in water
0.000003 ppm,
or 3 ppt
Fig. 11-15, p. 237
PROTECTING WILD SPECIES:
LEGAL AND ECONOMIC
APPROACHES
 International
treaties have helped reduce the
international trade of endangered and
threatened species, but enforcement is
difficult.

One of the most powerful is the 1975 Convention
on International Trade of Endangered Species
(CITES).
• Signed by 169 countries, lists 900 species that cannot
be commercially traded.
Case Study:
The U.S. Endangered Species Act
 One
of the world’s most far-reaching and
controversial environmental laws is the 1973
U.S. Endangered Species Act (ESA).


ESA forbids federal agencies (besides defense
department) to carry out / fund projects that
would jeopardize an endangered species.
ESA makes it illegal for Americans to engage in
commerce associated with or hunt / kill / collect
endangered or threatened species.
Endangered Species
 Because
of
scarcity of
inspectors,
probably no
more than 1/10th
of the illegal
wildlife trade in
the U.S. is
discovered.
Figure 11-19
PROTECTING WILD SPECIES: THE
SANCTUARY APPROACH
 The
U.S. has set aside 544
federal refuges for wildlife,
but many refuges are
suffering from environmental
degradation.
Pelican Island was the
nation’s first wildlife refuge.
Figure 11-20
What Can You Do?
Protecting Species
• Do not buy furs, ivory products, and other
materials made from endangered or threatened
animal species.
• Do not buy wood and paper products
produced by cutting remaining oldgrowth forests in the tropics.
• Do not buy birds, snakes, turtles, tropical fish,
and other animals that are taken from the wild.
• Do not buy orchids, cacti, and other plants that
are taken from the wild.
• Spread the word. Talk to your friends and
relatives about this problem and what they can
do about it.
Fig. 11-21, p. 246