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Chapter 18
Conservation of Biodiversity
Key Ideas
• Understand how genetic diversity, species diversity, and
ecosystem function are changing over time
• Identify the causes of declining biodiversity
• Describe the single-species approach to conserving
biodiversity including the major laws that protect
species
• Explain the ecosystem approach to conserving
biodiversity and how size, shape and connectedness
affect the number of species that will be protected
The 6th Mass Extinction




Local extinction: when a species is no longer found in
area it once inhabited, but is still found elsewhere.
Ecological extinction: when so few individuals of a
species are left that a species no longer plays a
significant ecological role in the communities where it is
found.
Biological extinction: when individuals of a species no
longer exist on Earth. FOREVER
We are currently losing approximately 50,000 species per
year.
Premature Extinction
Passenger
pigeon
Great auk
Dodo
Dusky seaside
sparrow
Aepyornis
(Madagascar)
Humans activities (habitat destruction and overhunting)
have caused the extinction of various species
Genetic Diversity


Scientists want to conserve genetic diversity so
that the species can survive environmental
change and inbreeding will not occur.
Inbreeding occurs when individuals with similar
genotypes, generally relatives, breed with each
other.
Categories of Endangerment




Extinct- no known species exist today
Threatened- species with a high risk of
extinction in the future
Near-threatened- species that are likely to
become threatened in the future
Least concern- species are widespread and
abundant
Threatened and Endangered
Species
Some species are
endangered or
threatened
because of
human activities.
Populations of
some species are
recovering (such
as the bald eagle
and peregrine
falcon).
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
HABITAT LOSS, DEGRADATION,
AND FRAGMENTATION
• The greatest threat to a species is the loss, degradation,
and fragmentation of where it lives.
Figure 11-7
Habitat Loss


For most species the greatest cause of decline and
extinction is habitat loss.
Most habitat loss is due to human development
Changing Forests
Some regions of the world have had large declines in forested land from 1980
to 2000
Habitat Fragmentation
• Occurs when a large area of habitat is divided
into smaller, scattered, and isolated patches
(“habitat islands”)
• Populations divided into smaller groups that are
more prone to predators and disease.
• Ex: Bobcats, Wolves, Sandpiper, Wood thrush
HABITAT LOSS, DEGRADATION,
AND FRAGMENTATION
• Reduction in
ranges of four
wildlife
species, mostly
due to habitat
loss and
overharvest.
Figure 11-8
Habitat Destruction in the U.S. &
Endangered Species
1. Agriculture
2. Commercial Development
3. Water Development: Dams
4. Outdoor Recreation
5. Livestock Grazing
6. Pollution- Peregrine Falcon
7. Logging of old growth forests- Northern
Spotted Owl
INVASIVE SPECIES
Kudzu vine was introduced
in the southeastern U.S. to
control erosion. It has taken
over native species habitats.
• Many nonnative
species provide us
with food, medicine,
and other benefits
but a a few can wipe
out native species,
disrupt ecosystems,
and cause large
economic losses.
Figure 11-A
Invasive Species



Alien species (exotic species)- species that live
outside their historical range.
Invasive species- when alien species spread
rapidly across large areas.
Ex- Kudzu Vine, Zebra Mussel, Silver Carp
Problems with Invasive Species
1. Cause premature extinction of native species.
Hawaii impacted the most.
2. Have no natural predators or competitors;
sometimes predators are introduced. Worsens
the problem.
3. Reduce biodiversity.
Zebra Mussels
Silver carp in the Mississippi River
Figure 12-9a
Page 235
Purple looselife
European starling
African honeybee
(“Killer bee”)
Marine toad
Water hyacinth
Japanese beetle
Nutria
Hydrilla
Deliberately Introduced Species
Salt cedar
(Tamarisk)
European wild boar
(Feral pig)
Figure 12-9b Page 235
Sea lamprey
(attached to lake trout)
Argentina fire ant
Brown tree snake
Eurasian muffle
Common pigeon
(Rock dove)
Formosan termite
Zebra mussel
Asian long-horned
beetle
Asian tiger mosquito
Gypsy moth larvae
Accidentally Introduced Species
Aquatic Invasive Species
Zebra Mussels
Water Hyacinth
Characteristics of
Successful
Invader Species
Characteristics of
Ecosystems Vulnerable
to Invader Species
• High reproductive rate,
short generation time
(r-selected species)
• Similar climate to habitat of
invader
• Pioneer species
• Absence of predators on
invading species
• Long lived
• High dispersal rate
• Release growthinhibiting chemicals into
soil
• Generalists
• High genetic variability
• Early successional systems
• Low diversity of native
species
• Absence of fire
• Disturbed by human
activities
INVASIVE
SPECIES
• Prevention is the best
way to reduce threats
from invasive species,
because once they
arrive it is almost
impossible to slow
their spread.
Figure 11-13
Case Study:
Restoring the Florida Everglades
• The world’s largest ecological restoration project
involves trying to undo some of the damage
inflicted on the Everglades by human activities.
– 90% of park’s wading birds have vanished.
– Other vertebrate populations down 75-95%.
– Large volumes of water that once flowed through the
park have been diverted for crops and cities.
– Runoff has caused noxious algal blooms.
– Invasive snakes have greatly reduced biodiversity
Restoring the
Florida
Everglades
• The project has
been attempting
to restore the
Everglades and
Florida water
supplies.
Figure 12-10
Pythons Removed From The Everglades
The chart below shows the number of pythons removed
from the park and neighboring areas between 1995 and 2010.
Researchers say the slight decrease in the number of pythons
captured in 2010 might be the result of a severe freeze in
January of that year.
Source: Michael Dorcas/Davidson University
http://www.npr.org/2012/01/30/146088909/invasive-pythons-put-squeeze-on-evergladesanimals
Overharvesting


When individuals of a species are removed at a rate
faster than the population can replace them.
Ex- dodo, American bison, passenger pigeon.
Extinction Threats From Smuggling,
Poaching, and Hunting
1. Illegal smuggling of endangered species; 3rd to
smuggling of drugs and weapons. Sadly, most animals
die in transit.
2. Exotic Pets- birds, reptiles, amphibians
3. Illegal Poaching- many animals are worth $$$.
Rhino horn- $13,000/lb
Causes of Extinction and Depletion
Fig. 25–13
Many species of sea turtles are
becoming endangered because
of loss of beach habitat for
laying eggs, taking of eggs for
food, and unintentional capture
by fishing boats.
Saving Sea Turtles With a Lights-Out
Policy in Florida
PROTECTING AND SUSTAINING
MARINE BIODIVERSITY
• A "Turtle Excluder
Device" is a grid of bars
with an opening either at
the top or the bottom of
the trawl net. The grid is
fitted into the neck of a
shrimp trawl. Small
animals such as shrimp
pass through the bars and
are caught in the bag end
of the trawl. When larger
animals, such as marine
turtles and sharks, are
captured in the trawl they
strike the grid bars and
are ejected through the
opening. Turtle Excluder Devices
(TEDs) - NOAA Fisheries
Overfishing and Extinction:
Gone Fishing, Fish Gone
• About 75% of the world’s commercially
valuable marine fish species are over fished
or fished near their sustainable limits.
– Big fish are becoming scarce.
– Smaller fish are next.
– We throw away 30% of the fish we catch.
– We needlessly kill sea mammals and birds.
Population Growth and
Pollution
• Each year plastic
items dumped
from ships and left
as litter on beaches
threaten marine
life.
Figure 12-3
Lacey Act
One of the earliest laws in the U.S. to
control the trade of wildlife.
 First passed in 1900, the act prohibited the
transport of illegally harvested game
animals, primarily birds and mammals,
across state lines.

CITES



Convention on International Trade in
Endangered Species of Wild Fauna and Flora
Developed in 1973 to control the international
trade of threatened plants and animals.
Today, CITIES is an international agreement
between 175 countries of the world.
Red List


The IUCN keeps a list of threatened species,
known as the red list.
Each country has its own way to monitor and
regulate the import and export of animals on the
list.
Conservation Legislation

Marine Mammal Protection Act- prohibits the
killing of all marine mammals in the U.S. and
prohibits the import or export of any marine
mammal body parts.
Endangered Species Act



Endangered Species Act- first passed in 1973, it
authorizes the U.S. Fish and Wildlife Service to
determine which species can be listed as
threatened or endangered and prohibits the
harming of these species.
Trading these species is also illegal.
The act also authorizes the government to
purchase habitat that is critical to the species.
MANAGING AND SUSTAINING
MARINE FISHERIES
• There are a number of ways to manage marine
fisheries more sustainably and protect marine
biodiversity.
• Some fishing communities regulate fish harvests on
their own and others work with the government to
regulate them.
– Modern fisheries have weakened the ability of many
coastal communities to regulate their own fisheries.
PROTECTING, SUSTAINING, AND
RESTORING LAKES AND RIVERS
• Dams can provide many human benefits but can
also disrupt some of the ecological services that
rivers provide.
– 119 dams on Columbia River have sharply reduced (94%
drop) populations of wild salmon.
– U.S. government has spent $3 billion in unsuccessful
efforts to save the salmon.
– Removing hydroelectric dams will restore native
spawning grounds.
Convention on Biological
Diversity


In 1992, nations came together and made a treaty
to protect biodiversity.
The treaty had three objectives: conserve
biodiversity, sustainably use biodiversity, and
equitably share the benefits that emerge from
the commercial use of genetic resources such as
pharmaceutical drugs.
Size, Shape and Connectedness


When designing and managing protected areas
we must consider how close to another area they
should be, how large the area is, and the amount
of edge habitat the area contains.
Edge habitat- the area where two different
communities come together, typically forming
an abrupt transition. Ex. A grassy field meeting
a forest.
Biosphere Reserves

Protected
areas
consisting of
zones that
vary in the
amount of
permissible
human
impact.
PROTECTING, SUSTAINING, AND
RESTORING WETLANDS
• Requiring government permits for filling or
destroying U.S. wetlands has slowed their loss, but
attempts to weaken this protection continue.
Figure 12-8
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
PROTECTING WILD SPECIES:
THE SANCTUARY APPROACH
• Gene banks, botanical gardens and using farms
to raise threatened species can help prevent
extinction, but these options lack funding and
storage space.
• Zoos and aquariums can help protect
endangered animal species by preserving some
individuals with the long-term goal of
reintroduction, but suffer from lack of space and
money.
RECONCILIATION ECOLOGY
• Reconciliation ecology involves finding ways to
share places we dominate with other species.
– Replacing monoculture grasses with native species.
– Maintaining habitats for insect eating bats can keep
down unwanted insects.
– Reduction and elimination of pesticides to protect
non-target organisms (such as vital insect pollinators).
Using Reconciliation Ecology to
Protect Bluebirds
• Putting up bluebird
boxes with holes too
small for (nonnative)
competitors in areas
where trees have been
cut down have helped
reestablish
populations.
Figure 11-B