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Chapter 5
Biological Diversity
and Conservation
Sections 1 and 2
Vanishing Species
Conservation of Biodiversity
Biodiversity
 The variety of species in a specific area.
 Easily measured by counting the number of
species living in an area.
 Increases closer to the equator.
Why is biodiversity important?
 Organisms are interdependent.
 Populations have adapted to live together
in communities.
 Brings stability to ecosystems.
 Humans depend on other species for
food, respiration, medicine, and raw
materials.
Extinction
 The disappearance of a species when
the last of its members dies.
 Natural process, resulting in both mass
extinction and background extinction
(Loss of one species per million species
per year).
 The current rate of extinction is much higher
than this.
Endangered Species
 A species is considered to be
endangered when its numbers become
so low that extinction is possible.
Threatened Species
 The population of a species is said to be
threatened when it is likely to become
endangered.
Exotic Species
 New species introduced into an ecosystem,
either intentionally or unintentionally.
 When introduced, exotic species are not as
vulnerable to competition and predation as
other species and can grow at a very quick
rate.
 Exotic species often severely decrease the
population size of species already present.
Habitat Loss
 One of the biggest reasons for decline in
biodiversity.
 Examples: Rainforests and Coral Reefs
Habitat Fragmentation
 Separation of wilderness areas form other
wilderness areas.
 Contributes to:
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Increased extinction of local species.
Disruption of ecological processes.
Increased risk of fire.
Changes in local climate.
New opportunities for invasions by introduced or
exotic species.
Habitat Fragmentation
 The smaller the fragment is the less
biodiversity it has.
 Geographic isolation can lead to genetic
isolation.
Edge Effect
 The edge of a habitat or ecosystem is
where one habitat or ecosystem meets
another.
 The differing conditions which exists
along the boundaries of a habitat or
ecosystem are called edge effects.
Edge Effect
 Edges tend to have greater biodiversity
because different habitats with different
species are brought together, along with
two different sets of abiotic factors.
 When an edge changes, animals might
migrate from their current area to the new
edge, bringing different species into
contact with one another.
Habitat Degradation
 The damage of a habitat by pollution.
 Three types of pollution:
 Air
 Water
 Land
Air Pollution
 Pollutants can enter the atmosphere in
many ways, including volcanic eruptions,
forest fires, and burning fossil fuels.
Air Pollution
 Acid Precipitation
 Rain, snow, sleet, and fog with low pH values.
 Has been linked to the deterioration of some
forests and lakes.
Air Pollution
 Acid Precipitation
 Sulfur dioxide from coal burning and nitrogen oxides
from auto exhaust combine with the water vapor in
the air to form acidic droplets of water vapor.
 This precipitation leaches calcium, potassium, and
other nutrients form the soil leading to the damage
and death of plants and trees.
 When added to the water cycle, acid rain also
degrades lake ecosystems.
Air Pollution
 Ozone
 Compound consisting of three oxygen
atoms.
 Found in the atmosphere between 15 and
35 km altitude.
 This layer of ozone absorbs ultraviolet
waves from the sun, reducing the amount of
radiation received by organisms on the
surface.
Air Pollution
 Ozone
 The Antarctic ozone hole is a reduction of up
to 60% in the ozone layer over some parts of
Antarctica during the spring. (The ozone
then increases over the summer.)
 This hole is caused by human-produced
chemicals, such as chlorofluorocarbons.
 Smaller, seasonal reductions are seen over
the Artic.
Water Pollution
 Degrades aquatic habitats in streams,
rivers, lakes, and oceans.
 Examples:
 Excess fertilizers and animal wastes can be
carried to waterways by rain. The increase
in nutrients cause algal blooms (excessive
growth of algae). As the algae die, they sink
and decay, removing needed oxygen form
the water.
Water Pollution
 Examples:
 Silt from eroded soils can clog the gills of
fish.
 Detergents, heavy metals, and industrial
chemicals can cause death in aquatic
organisms.
Land Pollution
 Examples:
 The average American produces 1.8 kg of
waste daily. Although some of this waste
may decompose quickly, most trash
becomes buried in landfills. Strict controls
on landfills are designed to lessen
contamination of groundwater.
 Use of chemicals, such as DDT can both
harm organisms and lead to habitat
degradation.
Natural Resources
 Parts of the environment that are useful
or necessary for living organisms.
 Include sunlight, water, air, and plant or
animal resources.
Conservation Biology
 Study and implementation of methods to
protect biodiversity.
 Based on principles of ecology.
U.S. Endangered Species Act
 Became law in 1973.
 Illegal to harm any species on the
endangered or threatened species list.
 Illegal for federal agencies to fund any
project that would harm any organisms
on these lists.
 This includes changing an ecosystem where
endangered or threatened species live.
Convention on International
Trade in Endangered Species
(CITES)
 Established lists of species for which
international trade is prohibited or
controlled.
 Has been endorsed by more than 120
countries.
Captivity
 Small numbers of organisms are
maintained by humans.
 Run into issues of space and money and the
possibility of the loss of the ability to survive
in the wild by the organism.
Reintroduction Programs
 Release of organisms into an area where
the same species once lived.
Preserving Habitats
 Creation of natural preserves and parks
to protect unique environments and
provide habitats for many organisms.
 Has been an effective way to maintain high
levels of biodiversity in small areas.
 U.S. established its first national park,
Yellowstone National Park, in 1872.
Habitat Corridors
 Protected strips of land that allow the
migration of organisms from one small
protected area to another.
 Help avoid genetic isolation.
Sustainable Use
 Use of natural resources in ways that will
benefit humans and still maintain the
ecosystem.